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21 pages, 2324 KiB  
Article
Geochronology and Genesis of the Shuigou Gold Deposit, Qixia-Penglai-Fushan Metallogenic Area, Jiaodong Peninsula, Eastern China: Constraints from SHRIMP U-Pb, 40Ar/39Ar Age, and He-Ar Isotopes
by Zhenjiang Liu, Shaobo Cheng, Changrong Liu, Benjie Gu and Yushan Xue
Minerals 2025, 15(1), 14; https://doi.org/10.3390/min15010014 - 26 Dec 2024
Viewed by 191
Abstract
The Jiaodong Peninsula is renowned for its significant gold reserves, which exceed 4500 tons. In this study, we conducted zircon SHRIMP U-Pb dating, 40Ar/39Ar geochronology, electron probe microanalysis (EPMA) analysis, and He-Ar isotope analysis on samples from the Shuigou gold [...] Read more.
The Jiaodong Peninsula is renowned for its significant gold reserves, which exceed 4500 tons. In this study, we conducted zircon SHRIMP U-Pb dating, 40Ar/39Ar geochronology, electron probe microanalysis (EPMA) analysis, and He-Ar isotope analysis on samples from the Shuigou gold deposit located in the Qixia-Penglai-Fushan metallogenic area of central Jiaodong. This quartz vein-type gold deposit is characterized by three mineralization stages: (I) the quartz-pyrite stage, (II) the quartz-polymetallic sulfide stage, and (III) the calcite stage. In stages I and II, gold primarily exists as native gold or electrum. Preliminary analysis suggests that the deposit contains rare critical metals, including bismuth (Bi), tellurium (Te), and antimony (Sb). The Sb is found as pyrargyrite in stage III, while the other critical elements occur as isomorphisms or nanoparticles within host minerals such as pyrite, native gold, and electrum. Geochronology data indicate that the pre-mineralization Guojialing monzogranite formed around 126 ± 1.6 Ma, the syn-mineralization muscovite formed at approximately 125 Ma, and the post-mineralization diorite porphyrite formed at 120.4 ± 1.8 Ma. The 3He/4He ratios of fluid inclusions in the main-stage pyrite range from 0.26 to 1.26 Ra, and the 40Ar/36Ar ratios vary from 383 to 426.6. These findings suggest that the Shuigou gold deposit formed during the destruction of the North China Craton (NCC), similar to other super-large gold deposits in the Jiaodong Mesozoic gold metallogenic province. Gold mineralization has been influenced by mantle, crustal, and meteoric fluids. Full article
18 pages, 11461 KiB  
Article
Identification and Geological Significance of Late Cambrian OIB-Type Volcanic Rocks in the Nailenggeledaban Area, Northern Yili Block
by Da Xu, Ming Cao, Meng Wang, Youxin Chen, Shaowei Zhao, Shengqiang Zhu, Tai Wen and Zhi’an Bao
Minerals 2025, 15(1), 7; https://doi.org/10.3390/min15010007 - 25 Dec 2024
Viewed by 39
Abstract
Paleozoic igneous rocks exposed in the northern Yili Block are thought to have resulted from the subduction of the North Tianshan oceanic crust. However, the exact timing of the transition of the northern margin of the Yili Block from a passive to an [...] Read more.
Paleozoic igneous rocks exposed in the northern Yili Block are thought to have resulted from the subduction of the North Tianshan oceanic crust. However, the exact timing of the transition of the northern margin of the Yili Block from a passive to an active continental margin remains unknown. In this paper, the petrological and geochemical features, zircon U-Pb chronology, Lu-Hf isotopes, and Sr-Nd isotopes of volcanic rocks in the Nailenggeledaban area on the northern margin of the Yili Block were studied. Zircon U-Pb dating results show that the crystallization ages of the volcanic rocks in the Nailenggeledaban area on the northern margin of the Yili Block are 491 ± 2 Ma and 500 ± 2 Ma, suggesting they were formed during the Late Cambrian. Geochemical features show that the volcanic rocks are alkaline basalts with rare earth and trace element distribution patterns similar to OIB, although they exhibit some degree of Zr and Hf depletion. The εHf(t) values of alkaline basalts in the Nailenggeledaban area at the northern Yili Block range from −3.48 to −1.00, with a TDM1 age of 1152 to 1263 Ma. The εNd(t) values range from −3.53 to −0.96, with a TDM1 age of 1471 to 2162 Ma. Combined with geochemical data, the alkaline basalt magma in the Nailenggeledaban area on the northern margin of the Yili Block may be derived from the Mesoproterozoic enriched lithospheric mantle. The composition of the mantle source area is potentially garnet lherzolite, and the magma appears to have been either unaffected or only minimally contaminated by crustal materials during the ascending process. On the basis of the research results of the Early Paleozoic tectonic evolution in the northern margin of the Yili Block, this paper proposes that the volcanic rocks in the Nailenggeledaban area, located on the northern margin of the Yili Block, were formed in a back-arc extensional environment resulting from the subduction of the North Tianshan Ocean (or Junggar Ocean) beneath the northern margin of the Yili Block during the Late Cambrian. Full article
(This article belongs to the Special Issue Geochronology and Geochemistry of Alkaline Rocks)
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Figure 1

Figure 1
<p>(<b>a</b>) Structural architecture of the Central Asian Orogenic Belt and (<b>b</b>) concise geological map outlining the Western Tianshan Orogen Belt in China (according to Gao et al., 2009a [<a href="#B21-minerals-15-00007" class="html-bibr">21</a>]).</p>
Full article ">Figure 2
<p>Location map of Late Cambrian basalt samples in the Nailenggeledaban area on the northern YB (modified after Dong et al., 2009 [<a href="#B36-minerals-15-00007" class="html-bibr">36</a>]).</p>
Full article ">Figure 3
<p>(<b>a</b>) TS21-02, (<b>b</b>) TS2207 field photos, and (<b>c</b>) TS21-02, (<b>d</b>) TS2207 microscope photos of basalts in the Nailenggeledaban area. Pl: plagioclase, Px: pyroxene.</p>
Full article ">Figure 4
<p>(<b>a</b>) Chondrite-normalized REE patterns and (<b>b</b>) space primitive mantle-normalized trace element (normalization values are from Sun et al., 1989 [<a href="#B48-minerals-15-00007" class="html-bibr">48</a>]).</p>
Full article ">Figure 5
<p>Zircon CL images of basalts (in the figure, the red solid circle represents the laser ablation position of zircon age, and the yellow dotted circle represents the analysis position of zircon Lu-Hf isotope).</p>
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<p>Zircon U-Pb age concordia diagrams of basalts in the Nailenggeledaban area.</p>
Full article ">Figure 7
<p>ε<sub>Hf</sub>(t)-t-plot for the zircon crystals of basalts in the Nailenggeledaban area.</p>
Full article ">Figure 8
<p>(<sup>87</sup>Sr/<sup>86</sup>Sr)<span class="html-italic"><sub>i</sub></span>-ε<sub>Nd</sub>(t) plot for the basalts in the Nailenggeledaban area (modified after Zimmer et al., 1995 [<a href="#B50-minerals-15-00007" class="html-bibr">50</a>]). DM: depleted mantle, MORB: Mid-Ocean Ridge Basalt, OIB: Ocean Island Basalt.</p>
Full article ">Figure 9
<p>(<b>a</b>) Nb/La-(Th/Nb)<sub>N</sub> diagram and (<b>b</b>) La/Ba-La/Nb diagram of basalt in the Nailenggeledaban area (base map according to Fitton et al., 1991, 1995 [<a href="#B57-minerals-15-00007" class="html-bibr">57</a>,<a href="#B58-minerals-15-00007" class="html-bibr">58</a>]). OIB: Ocean Island Basalt.</p>
Full article ">Figure 10
<p>Harker variation diagram of the basalts in Nailenggeledaban area.</p>
Full article ">Figure 11
<p>Sm/Yb-Sm diagram of basalt in the Nailenggeledaban area (the trends of the partial melting models are derived from Aldanmaz et al., 2000 [<a href="#B61-minerals-15-00007" class="html-bibr">61</a>]). DM: depleted mantle, PM: enriched mantle, N-MORB: Normal Mid-Ocean Ridge Basalt, E-MORB: Enriched Mid-Ocean Ridge Basalt.</p>
Full article ">Figure 12
<p>(<b>a</b>) Zr/Nb-La/Y diagram and (<b>b</b>) La/Ba-La/Nb diagram of basalts in the Nailenggeledaban area (modified after Xia et al., 2019 [<a href="#B62-minerals-15-00007" class="html-bibr">62</a>]). OIB: Ocean Island Basalt, MORB: Mid-Ocean Ridge Basalt, N-MORB: Normal Mid-Ocean Ridge Basalt.</p>
Full article ">Figure 13
<p>(<b>a</b>) Zr/Y-Zr/Nb diagram and (<b>b</b>) Zr/Y-Y/Nb-Zr/Nb diagram of basalts in the Naile-nggeledaban area (modified after Fodor et al., 1984 [<a href="#B63-minerals-15-00007" class="html-bibr">63</a>]).</p>
Full article ">Figure 14
<p>Construction environment discrimination diagram in basalts. (<b>a</b>) [<a href="#B75-minerals-15-00007" class="html-bibr">75</a>]: WPB: within-plate basalt; MORB: mid-ocean ridge basalt; VAB: volcanic arc basalt. (<b>b</b>) [<a href="#B76-minerals-15-00007" class="html-bibr">76</a>]: I: N-MORB area at the edge of plate divergence; II: basalt area at the edge of the convergent plate (II1: ocean island arc basalt; II2: continental margin island arc and continental margin volcanic arc basalt area); III: ocean island, seamount basalt area, and TMORB, E-MORB area; IV: continental intraplate basalt area (IV1: intracontinental rift valley and continental rift valley basalt area; IV2: intracontinental rift alkaline basalt area; IV3: continental extension zone (or initial rift) basalt area); V: mantle plume basalt area. (<b>c</b>) [<a href="#B77-minerals-15-00007" class="html-bibr">77</a>] (Cabanis and Lecolle, 1989). (<b>d</b>) [<a href="#B78-minerals-15-00007" class="html-bibr">78</a>]: AI, AII: in-plate alkaline basalt; AII, C: intraplate tholeiitic basalt, B: enriched mid-ocean ridge basalt, D: depleted mid-ocean ridge basalt; C, D: volcanic arc basalt.</p>
Full article ">
43 pages, 43241 KiB  
Article
Excess 40Ar in Alkali Feldspar and 206,207Pb in Apatite Caused by Fluid-Induced Recrystallisation in a Semi-Closed Environment in Proterozoic (Meta)Granites of the Mt Isa Inlier, NE Australia
by Daniil Popov, Richard Spikings, André Navin Paul, Maria Ovtcharova, Massimo Chiaradia, Martin Kutzschbach, Alexey Ulianov, Gary O’Sullivan, David Chew, Kalin Kouzmanov, Eszter Badenszki, J. Stephen Daly and Joshua H. F. L. Davies
Geosciences 2024, 14(12), 358; https://doi.org/10.3390/geosciences14120358 - 21 Dec 2024
Viewed by 311
Abstract
Interpretation of 40Ar/39Ar dates of alkali feldspar and U-Pb dates of apatite depends on the dominant mechanism of isotopic transport in these minerals, which can be either diffusion or fluid-assisted dissolution-reprecipitation. To clarify the contributions of these processes, we have [...] Read more.
Interpretation of 40Ar/39Ar dates of alkali feldspar and U-Pb dates of apatite depends on the dominant mechanism of isotopic transport in these minerals, which can be either diffusion or fluid-assisted dissolution-reprecipitation. To clarify the contributions of these processes, we have conducted a holistic study of alkali feldspar, apatite and other minerals from the Mt. Isa Inlier in NE Australia. Mineral characterisation by electron microscopy, optical cathodoluminescence imaging and element mapping reveal a complex interplay of textures resulting from magmatic crystallisation, deuteric recrystallisation, local deformation with subsequent higher-temperature alteration, and finally ubiquitous low-temperature alteration. U-Pb and Pb isotopic data for zircon, apatite, fluorite and alkali feldspar suggest that the latter event occurred at ~300 Ma and was associated with fluid-assisted exchange of Pb isotopes between minerals in the same rock, causing some apatite grains to have 207Pb-corrected U-Pb dates that exceed their crystallisation age. However, this event had no unequivocal effect on the 40Ar/39Ar or Rb-Sr systematics of the alkali feldspar, which were disturbed by higher-temperature alteration at ~1450 Ma. The age of the latter event is derived from Rb-Sr data. 40Ar/39Ar dates are very scattered and suggest that 40Ar redistribution proceeded by diffusion in the presence of traps in some places and by dissolution-reprecipitation with variable amounts of recycling in other places. Our results demonstrate the complex effects that interaction with limited amounts of fluids can have on 40Ar/39Ar dates of alkali feldspar and U-Pb dates of apatite and thereby reinforce previous critique of their suitability for thermochronological reconstructions. We further identify and discuss potential implications for noble gas geochronology of groundwaters and fission track dating of apatite. Full article
(This article belongs to the Section Geochemistry)
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Figure 1

Figure 1
<p>Map of metamorphic grades and the major felsic plutons in the southern part of the Mt. Isa Inlier, adapted from [<a href="#B23-geosciences-14-00358" class="html-bibr">23</a>].</p>
Full article ">Figure 2
<p>CL images of the samples giving an overview of rock textures and mineralogy (<b>a</b>–<b>d</b>).</p>
Full article ">Figure 3
<p>Representative BSE images and <sup>206</sup>Pb/<sup>238</sup>U dates of zircon from the sample suite. Note the patchy and veining textures that indicate fluid-mediated recrystallisation. These textures are present in all samples, but are particularly common in the Williams, Kalkadoon and Sybella S samples. Analytical 2σ uncertainties are shown, which represent most of the external uncertainty. Circles without numbers attached to them show locations of bad analyses with noisy signals that did not yield dates. Contrast in (<b>a</b>,<b>b</b>) is mostly structural, and zones with higher U content and thus expected radiation damage appear darker. Contrast in (<b>c</b>) is a mix of structural and compositional: some dark zones are richer in U than bright ones (mostly in recrystallised regions), while other dark zones have less U than bright ones (mostly in regions with magmatic texture). Contrast in (<b>d</b>) is mostly compositional, and zones with high U content appear bright.</p>
Full article ">Figure 4
<p>Representative BSE images of U-Th-bearing silicates other than zircon. (<b>a</b>,<b>b</b>) Examples of patchy textures and decomposition of titanite in the Williams (<b>a</b>) and Sybella S (<b>b</b>) samples. (<b>c</b>) An example of decomposed allanite from the Sybella S sample. (<b>d</b>) An example of thorite from the Sybella S sample.</p>
Full article ">Figure 5
<p>Representative CL images and chemical maps for apatite from the Williams sample (<b>a</b>–<b>p</b>) and a schematic summary of the observed textures (<b>q</b>). Numbers in red are either ID-TIMS bulk-grain (those with unspecified locations) or in situ LA-MC-ICP-MS (those with specified locations) <sup>207</sup>Pb-corrected U-Pb dates with 2σ uncertainties that do not include the uncertainty on the initial Pb composition. Note that some grains have a magmatic appearance due to their regular oscillatory zoning and Th/U ratios of ~10, while other grains have replacement zones and veins with lower Th/U ratios or display lower Th/U ratios throughout.</p>
Full article ">Figure 6
<p>Representative CL images and chemical maps for apatite from the Kalkadoon sample (<b>a</b>–<b>e</b>) and schematic summaries of the observed textures in euhedral (<b>f</b>) and anhedral (<b>g</b>) crystals. The number in red is one of the in situ LA-MC-ICP-MS <sup>207</sup>Pb-corrected U-Pb dates with a 2σ uncertainty that does not include the uncertainty on the initial Pb composition. Note the diversity of textures and chemical compositions, and the uncorrelated differences in zoning patterns revealed by different chemical maps and CL images for the same crystals. In our interpretation, regions with Th/U and La/Y ratios of ~10 and ~2, respectively, are relatively fresh, while regions with lower Th/U and La/Y ratios are affected by one or multiple alteration events.</p>
Full article ">Figure 7
<p>Representative CL images and chemical maps for apatite from the Sybella samples (<b>a</b>–<b>i</b>) and a schematic summary of the observed textures (<b>j</b>). Numbers in red are either ID-TIMS bulk-grain (those with unspecified locations) or in situ LA-MC-ICP-MS (those with specified locations) <sup>207</sup>Pb-corrected U-Pb dates with 2σ uncertainties that do not include the uncertainty on the initial Pb composition. Pure yellow regions in the Th/U and La/Y maps for the crystals in (<b>e</b>,<b>g</b>) have much greater values than indicated on the scalebar (compare with Th, U, La and Y maps). Concentrations in minerals other than apatite are expected to be highly inaccurate because all images were obtained by using Ca as the internal standard and assuming that it is homogeneously distributed in the ablated material. The crystal in (<b>b</b>) has a crack along its <span class="html-italic">c</span> axis that formed during sample preparation and is only visible in BSE and optical microscope images (<a href="#app1-geosciences-14-00358" class="html-app">Supplementary Archive</a>). This contrasts with the cracks in the crystals in (<b>d</b>,<b>e</b>), which are visible in chemical maps and thus existed prior to sample preparation. Note that most grains display textures indicative of alteration, such as replacement zones along crystal edges, anastomosing thin veins in more interior parts of crystals and the cracks that are visible in chemical maps.</p>
Full article ">Figure 8
<p>Representative CL (<b>a</b>) and BSE (<b>b</b>,<b>c</b>) images of alkali feldspar from the Williams sample and a schematic summary of the observed textures (<b>d</b>). The images were taken from the surface near (010), and sub-horizontal cracks in them are the (001) cleavage. Note the complex interplay between the textures formed by magmatic crystallisation with subsequent Na-K interdiffusion, such as the resorption zones and the Na-rich lamellae of various scales, some of which are cut by pull-aparts (see [<a href="#B91-geosciences-14-00358" class="html-bibr">91</a>]), and the two broad generations of textures resulting from fluid-induced recrystallisation, namely the replacement perthite veins and the veins of very porous feldspar.</p>
Full article ">Figure 9
<p>Representative CL (<b>a</b>) and BSE (<b>b</b>,<b>c</b>) images of alkali feldspar from the Kalkadoon sample and a schematic summary of the observed textures (<b>d</b>). The images were taken from the surface near (010), and sub-horizontal cracks in them are the (001) cleavage. Note the complex interplay between different feldspar generations. The earliest phase is K-rich feldspar with two types of Na-rich lamellae, one of which is represented by flat platelets oriented along the Murchison plane and the other by flame-like formations that often have serrated boundaries and align with the (001) cleavage. It is cut first by several generation of thick veins that are predominantly composed of K-feldspar and then by myriads of thin veins of highly porous K-feldspar.</p>
Full article ">Figure 10
<p>Representative CL images of alkali feldspar from the Sybella S (<b>a</b>) and Sybella N (<b>b</b>) samples and a schematic summary of the observed textures (<b>c</b>). Note that earlier metamorphic Na and K-rich feldspars with brighter CL are cut by irregular veins and patches of replacive Na and K-rich feldspars with darker CL.</p>
Full article ">Figure 11
<p>Tera-Wasserburg plots summarising Pb and U-Pb isotope data for the Williams (<b>a</b>), Kalkadoon (<b>b</b>), Sybella S (<b>c</b>) and Sybella N (<b>d</b>) samples. In situ LA-ICP-MS U-Pb analyses of zircon from each sample are often discordant, pointing to a Pb loss event at ~300 Ma. <sup>207</sup>Pb/<sup>206</sup>Pb ratios of the released Pb fall slightly below the discordia intercepts with the vertical axes. Other points on the vertical axis are the <sup>207</sup>Pb/<sup>206</sup>Pb ratios in alkali feldspar as measured by bulk-grain MC-ICP-MS analysis and in common Pb as predicted by the model of Stacey and Kramers [<a href="#B40-geosciences-14-00358" class="html-bibr">40</a>] for the crystallisation ages of the samples. These are connected via hand-drawn tie-lines of matching colours to the upper discordia-concordia intercepts. U-Pb results for apatite obtained by both in situ LA-MC-ICP-MS and bulk-grain ID-TIMS analysis are considerably scattered and sometimes plot left of the said tie-lines, suggesting that some <sup>207</sup>Pb-corrected U-Pb dates of apatite exceed the inferred crystallisation ages of the rocks they were derived from. The same applies to bulk-grain ID-TIMS U-Pb analyses of fluorite. Data for U-bearing phases are presented as 95% confidence ellipses, which were constructed using Isoplot [<a href="#B105-geosciences-14-00358" class="html-bibr">105</a>]. The same software was used to calculate intercept dates, which are likewise quoted with 95% uncertainty intervals.</p>
Full article ">Figure 12
<p>Ahrens-Wetherill plot with all of our in situ LA-ICP-MS U-Pb analyses of zircon from Proterozoic (meta)granites of the Mt. Isa Inlier. Different samples are shown in different colours, while lines represent discordia fits that were obtained as explained in the main text. Data are presented as 95% confidence ellipses, which were constructed using Isoplot [<a href="#B105-geosciences-14-00358" class="html-bibr">105</a>]. Note that a significant proportion of discordant data points were obtained for each sample, and that these generally delineate trends intersecting the concordia at ~300 Ma.</p>
Full article ">Figure 13
<p>Rb-Sr analyses of alkali feldspar from the Kalkadoon sample. (<b>a</b>) Isochron plot with all the Rb-Sr data that we have acquired. Data are presented as 95% confidence ellipses that were constructed using Isoplot [<a href="#B105-geosciences-14-00358" class="html-bibr">105</a>]. (<b>b</b>) Isochron dates obtained for different combinations of analyses. Of these only dates with MSWD ≤ 1.8 can be deemed statistically acceptable following the criterion of Wendt and Carl [<a href="#B104-geosciences-14-00358" class="html-bibr">104</a>]. External uncertainties are shown at the 95% confidence level.</p>
Full article ">Figure 14
<p><sup>40</sup>Ar/<sup>39</sup>Ar results for alkali feldspar from the Kalkadoon sample obtained by in situ analysis of the crystal shown in <a href="#geosciences-14-00358-f008" class="html-fig">Figure 8</a> (<b>a</b>,<b>b</b>) and by step-heating of conventionally separated aliquot of 0.3–0.5 mm fragments (<b>c</b>,<b>d</b>). (<b>a</b>) Inverse isochron plot for the in situ <sup>40</sup>Ar/<sup>39</sup>Ar data, showing that virtually all analyses are within uncertainty of the horizontal axis. Vertical lines indicate <sup>39</sup>Ar/<sup>40</sup>Ar ratios that correspond to the inferred crystallisation ages of the feldspar regions having blue (zircon upper intercept) and purple (Rb-Sr isochron date for veins) colour in CL images, and also the <sup>40</sup>Ar/<sup>39</sup>Ar plateau date. (<b>b</b>) Comparison of in situ <sup>40</sup>Ar/<sup>39</sup>Ar dates from the same two feldspar types along with probability density functions that they define. (<b>c</b>) Inverse isochron for step-heating <sup>40</sup>Ar/<sup>39</sup>Ar data with the same vertical lines as in (<b>a</b>). Most of the data lie on the horizontal axis. (<b>d</b>) Age spectrum with a poorly defined plateau that was obtained by step-heating analysis. Age spectrum and inverse isochron plots were made using Isoplot [<a href="#B105-geosciences-14-00358" class="html-bibr">105</a>], which was also used to calculate the plateau date with its external uncertainty. Uncertainties other than that of the plateau date are analytical, which for individual analyses covers most of the full uncertainty. All uncertainties are shown at the 95% confidence level.</p>
Full article ">Figure 15
<p>Schematic representation of the effects of fluid-assisted isotope redistribution in a semi-closed environment on the U-Pb systematics of apatite (<b>a</b>) and <sup>40</sup>Ar/<sup>39</sup>Ar systematics of alkali feldspar (<b>b</b>).</p>
Full article ">Figure 16
<p>Illustration of our approach to model chemical and isotopic effects of fluid-induced dissolution-reprecipitation (<b>a</b>) and the obtained results (<b>b</b>–<b>g</b>). See text for details.</p>
Full article ">
19 pages, 7027 KiB  
Article
The Northernmost Effects of the Neo-Tethys Oceanic Slab Subduction Under the Lhasa Terrane: Evidence from the Mazin Rhyolite Porphyry
by Zhuosheng Wang, Nan Wang, Zhibo Liu and Xudong Ma
Minerals 2024, 14(12), 1292; https://doi.org/10.3390/min14121292 - 20 Dec 2024
Viewed by 320
Abstract
The India–Asia collision represents the most significant geological event in the formation of the Tibetan plateau. The subsidence of the Neo-Tethys oceanic slab and the closure of the ocean basin were precursors of the India–Asia collision. The Linzizong volcanic formations, which range in [...] Read more.
The India–Asia collision represents the most significant geological event in the formation of the Tibetan plateau. The subsidence of the Neo-Tethys oceanic slab and the closure of the ocean basin were precursors of the India–Asia collision. The Linzizong volcanic formations, which range in age from the late Cretaceous to early Cenozoic (70–40 Ma), are widely distributed across the Lhasa terrane and are considered products of the closure of the Neo-Tethys oceanic basin and the India–Asia collision. Here, we report a newly identified series of rhyolite porphyries, which share similar age and geochemical features with typical Linzizong volcanic formations. These porphyries are the northernmost extension of Linzizong volcanic formations discovered to date. Zircon U-Pb dating suggests that they formed between 58.8 and 56.1 Ma. These porphyries are characterized by high SiO2 (75.04%–77.82%), total alkali (K2O: 4.71%–5.03%), and Na2O (2.54%–3.63%) values; relatively low Al2O3 (12.30%–13.62%) and MgO (0.13%–0.33%) values; and low Mg# values (15.8–25.7). They also exhibit strong enrichment in light rare earth elements ([La/Yb]N = 3.76–11.08); negative Eu anomalies (Eu/Eu* = 0.10–0.32); Rb, Ba, Th, U, and Pb enrichments; as well as Nb and Ta depletions. The samples have relatively low εNd(t) values (−6.0 to −3.8) and variable zircon εHf(t) values (−6.3 to +3.6). These features suggest they originated from the remelting of the juvenile lower crust of the North Lhasa terrane under high-temperature and extensional conditions. We propose that the Mazin rhyolite porphyries resulted from mantle-derived magma diapirism, triggering juvenile lower crust remelting during Neo-Tethys oceanic slab rollback at the onset of the India–Asia collision. These findings provide new insights into the magmatic processes associated with early collisional tectonics. Full article
(This article belongs to the Special Issue Tectonic Evolution of the Tethys Ocean in the Qinghai–Tibet Plateau)
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Figure 1

Figure 1
<p>(<b>a</b>) Topographic map of Tibetan Plateau. (<b>b</b>) Geological map illustrating spatial distribution of Mesozoic-Cenozoic magmatism (modified from [<a href="#B40-minerals-14-01292" class="html-bibr">40</a>]). (<b>c</b>) Geological map of study area, Baingoin County, northern Lhasa Terrane (modified from [<a href="#B41-minerals-14-01292" class="html-bibr">41</a>]). LMF = Luobadui–Milashan Fault; KF = Karakoram Fault; ATF = Altyn Tagh Fault; IYZS = Indus-Yarlung Zangbo suture zone; SNMZ = Shiquan River–Nam Tso mélange zone; JSS = Jinsha suture zone; BNS = Bangong–Nujiang suture zone.</p>
Full article ">Figure 2
<p>(<b>a</b>) Long view of Mazin rhyolite porphyry. (<b>b</b>) Photograph of Mazin rhyolite porphyry outcrop. (<b>c</b>) Close-up image of Mazin rhyolite porphyry. (<b>d</b>) Breccias from wall rock associated with Mazin rhyolite porphyry.</p>
Full article ">Figure 3
<p>Zircon U-Pb isotope concordia diagrams and representative cathodoluminescence images of zircon from Mazin rhyolite porphyry, Baingoin County, northern Lhasa Terrane. (<b>a</b>) BGA38-3; (<b>b</b>) BGA40-3; ‘n’ denotes number of samples; ‘MSWD’ represents mean square of weighted deviations.</p>
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<p>Diagram of zircon εHf(t) versus zircon <sup>206</sup>Pb/<sup>238</sup>U age (Ma). Zircon εHf(t) data for Xiongmei granite were compiled from [<a href="#B43-minerals-14-01292" class="html-bibr">43</a>]; for Norite, data were compiled from [<a href="#B44-minerals-14-01292" class="html-bibr">44</a>]; and for Xietongmen rhyolite, data were compiled from [<a href="#B29-minerals-14-01292" class="html-bibr">29</a>].</p>
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<p>(<b>a</b>) Total alkalis versus SiO<sub>2</sub> diagram. (<b>b</b>) Diagram of Zr/TiO<sub>2</sub> × 0.0001 versus Nb/Y. (<b>c</b>) A/NK versus A/CNK [where A/NK = molar Al<sub>2</sub>O<sub>3</sub>/(Na<sub>2</sub>O + K<sub>2</sub>O); A/CNK = molar Al<sub>2</sub>O<sub>3</sub>/(CaO + Na<sub>2</sub>O + K<sub>2</sub>O)] [<a href="#B45-minerals-14-01292" class="html-bibr">45</a>]; (<b>d</b>) K<sub>2</sub>O versus SiO<sub>2</sub> [<a href="#B46-minerals-14-01292" class="html-bibr">46</a>].</p>
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<p>(<b>a</b>) Chondrite-normalized rare earth element spidergram and (<b>b</b>) primitive mantle-normalized trace element spidergram for Mazin rhyolite porphyry, Baingoin County, North Lhasa Terrane. Normalized values were sourced from [<a href="#B47-minerals-14-01292" class="html-bibr">47</a>].</p>
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<p>(<b>a</b>) <span class="html-italic">w</span>(SiO<sub>2</sub>)/% versus <span class="html-italic">w</span>(P<sub>2</sub>O<sub>5</sub>)/%; (<b>b</b>) 10000Ga/Al versus <span class="html-italic">w</span>(Zr)/10<sup>−6</sup>; (<b>c</b>) Zr+Ce+Nb+Y versus10000 Ga/Al; (<b>d</b>) TFeO/MgO versus Zr+Nb+Ce+Y (FG = high-grade metamorphic granite, OGT = undifferentiated I-type, S-type, and M-type granites) [<a href="#B65-minerals-14-01292" class="html-bibr">65</a>,<a href="#B66-minerals-14-01292" class="html-bibr">66</a>].</p>
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<p>(<b>a</b>) Sr\Y versus La/Yb. (<b>b</b>) Al<sub>2</sub>O<sub>3</sub>\(FeO<sup>T</sup> + MgO + TiO<sub>2</sub>) versus Al<sub>2</sub>O<sub>3</sub> + FeO<sup>T</sup> + TiO<sub>2</sub> (HP means high pressure; LP means low pressure) [<a href="#B71-minerals-14-01292" class="html-bibr">71</a>].</p>
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<p>(<b>a</b>) Y × 10<sup>−6</sup> versus SiO<sub>2</sub>; (<b>b</b>) Nb/Zr versus Zr × 10<sup>−6</sup>; (<b>c</b>) R2 versus R1; (<b>d</b>) Rb × 10<sup>−6</sup> versus (Y + Nb) × 10<sup>−6</sup> (modified based on [<a href="#B80-minerals-14-01292" class="html-bibr">80</a>,<a href="#B81-minerals-14-01292" class="html-bibr">81</a>,<a href="#B82-minerals-14-01292" class="html-bibr">82</a>]).</p>
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<p>Schematic illustrations depicting the remote effects of the Paleogene geodynamic evolution processes associated with the Neo-Tethys oceanic tectonic regime in the northern Lhasa Terrane.</p>
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22 pages, 7722 KiB  
Article
Late Paleozoic Tectonics of the NW Tarim Block: Insights from Zircon Geochronology and Geochemistry in Xinjiang, China
by Baozhong Yang, Ao Lv, Xiangrong Zhang, Yejin Zhou, Wenxiao Zhou and Ernest Chi Fru
Minerals 2024, 14(12), 1288; https://doi.org/10.3390/min14121288 - 19 Dec 2024
Viewed by 392
Abstract
The Late Paleozoic strata on the northwestern margin of the Tarim Block provide valuable insights into the subduction and collision processes that formed the Southwest Tianshan Orogenic Belt. This study integrates detrital zircon U-Pb dating and sandstone geochemical analysis of the Balikelike and [...] Read more.
The Late Paleozoic strata on the northwestern margin of the Tarim Block provide valuable insights into the subduction and collision processes that formed the Southwest Tianshan Orogenic Belt. This study integrates detrital zircon U-Pb dating and sandstone geochemical analysis of the Balikelike and Kalundaer formations to examine sedimentary provenance and tectonic settings during the Cisuralian–Guadalupian Epoch in the Keping area on the northwestern margin of the Tarim Block. Three of five Precambrian detrital zircon U-Pb age populations, 2500–2300 and 2000–1800 Ma and 900–600 Ma, are likely related to the fragmentation of the Columbia supercontinent and Rodinia’s assembly, respectively. Two Paleozoic detrital zircons, 500–380 Ma, are associated with Paleozoic magmatism. Among them, ~295 Ma zircons are associated with post-collisional extension and emplacement of the Tarim Large Igneous Province. Geochemical analysis of sandstones, coupled with tectonic reconstruction, indicates a passive continental margin setting in the northwestern margin of the Tarim Block during the Silurian Period, later transitioned to a foreland basin from the Pennsylvanian to the Guadalupian Epochs. The crustal transformation from the Middle-late Devonian to Early Mississippian marked the closure of the South Tianshan Ocean (STO), involving a soft collision and significant uplift, with major orogenesis occurring in the Late Guadalupian. Five key stages are identified in the evolution of the foreland basin: (1) Middle-late Devonian to Early Mississippian initiation (remnant ocean basin stage); (2) Late Mississippian to Early Pennsylvanian early stage; (3) Late Pennsylvanian to Early Cisuralian middle stage; (4) the Late Cisuralian stage; and (5) the terminal Guadalupian stage. These findings provide new constraints on when STO closed and propose an innovative foreland basin evolution model during the late post-collisional phase from the Late Mississippian to Guadalupian. Collectively, the data advance our understanding of the tectonic processes that shaped the northwestern Tarim Block, with broader implications for Paleozoic geodynamics. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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Figure 1

Figure 1
<p>(<b>a</b>) Tectonic location of the study area; (<b>b</b>) tectonic geological map of the northern part of the Tarim Block, the western part of the STOB, and adjacent areas (Modified from Han (2015) [<a href="#B17-minerals-14-01288" class="html-bibr">17</a>]). Major faults: ① Nikolaev Line-North Nalati Fault; ② Atbashy–Inylchek–South Nalati Fault; ③ North Tarim Fault; ④ Talas–Ferghana Fault. (<b>c</b>) Geological map of the Keping area. KKF = Kangkelin Formation, comprising limestone, bioclastic limestone, calcareous sandstone, and mudstone; BLF = Balikelike Formation, comprising greyish limestone, grey-black bioclastic limestone, light grey-black mud-limestone, and an interbedded basalt layer; KLF = Kalundaer Formation, comprising lenticular conglomerates, calcareous sandstones, siltstones, and mudstones. (PM301-Section PM 301; PM106-Section PM106; PM107-Section PM107).</p>
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<p>Stratigraphic division scheme and sedimentary environments in the Keping and adjacent areas. S<sub>1</sub><span class="html-italic">k</span>-Kepingtage Fm.; S<sub>2–4</sub><span class="html-italic">t</span>-Tataaiertage Fm.; C<sub>1</sub><span class="html-italic">b</span>-Bashisuogong Fm.; C<sub>2</sub><span class="html-italic">b</span>-Biegentawu Fm.; P<sub>1</sub><span class="html-italic">ku</span>-Kupukuziman Fm.; P<sub>1–2</sub><span class="html-italic">ka</span>-Kaipaizileike Fm.; P<sub>2</sub><span class="html-italic">s</span>-Shajingzi Fm. Fm. = Formation; Thk. = Thickness; Others shown in text. The horizontal lines in the diagram indicate isochrones, not thickness.</p>
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<p>Sampling position in the stratigraphic column of the Cisuralian–Guadalupian Series in the study area. (<b>a</b>) Section PM301; (<b>b</b>) Section PM106; (<b>c</b>) Section PM107.</p>
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<p>Lithological characteristics of the sandstone of the Balikelike and Kalundaer formations (<b>a</b>,<b>b</b>,<b>e</b>,<b>h</b>) Field photographs; Others are micrographs. (-) Under polarized light microscope; (+) Between crossed polarizers. Lvi: Plate-like plagioclase; Lvm: Fine volcanic rock fragments; Q: Quartz. (<b>a</b>). The unconformity contact between the Kangkelin and Keziertage formations; (<b>b</b>–<b>d</b>). The calcareous fine sandstone of the Balikelike Formation from Sample 106-23; (<b>e</b>–<b>g</b>). The tuffaceous fine lithic sandstone of the Kalundaer Formation from Sample 301-38; (<b>h</b>–<b>j</b>). Calcareous fine sandy siltstone of the Kalundaer Formation from Sample 301-71. Other legends are shown in <a href="#minerals-14-01288-f001" class="html-fig">Figure 1</a>, <a href="#minerals-14-01288-f002" class="html-fig">Figure 2</a> and <a href="#minerals-14-01288-f003" class="html-fig">Figure 3</a>.</p>
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<p>The satellite images (<b>a</b>,<b>d</b>) and the field photographs (<b>b</b>,<b>c</b>,<b>e</b>,<b>f</b>) of the mafic dyke and basalt in the study area. (<b>a</b>–<b>c</b>) The mafic dyke cut through the Devonian system, covered by the Kangkelin Formation, with an age of 308 Ma: (<b>d</b>–<b>f</b>) The basalt in the Balikelike Formation, with an age of 287.6 Ma.</p>
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<p>CL images of representative detrital zircons analyzed for U-Pb ages from the Balikelike and Kalundaer formations, NW Tarim. White circles indicate the location of sample spots measured to obtain the U-Pb ages.</p>
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<p>Concordia and histogram-probability density diagrams of detrital zircon U-Pb data for sandstone samples from the Balikelike and Kalundaer formations, NW Tarim. Of all ages, those with more than 10% discordance degrees were excluded. Errors are shown at 1 sigma level. (<b>a</b>,<b>b</b>) Sample B106-23; (<b>c</b>,<b>d</b>) Sample B301-38; (<b>e</b>,<b>f</b>) Sample B301-71.</p>
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<p>(<b>a</b>) UCC-normalized multi-element diagrams for samples of the Balikelike and Kalundaer formations. Normalized to UCC values from Rudnick (2003) [<a href="#B48-minerals-14-01288" class="html-bibr">48</a>]; (<b>b</b>) chondrite-normalized REE patterns for samples of the Balikelike and Kalundaer formations. Normalized to chondritic values from Taylor (1995) [<a href="#B49-minerals-14-01288" class="html-bibr">49</a>]. The standard composition of average UCC after Rudnick (2003) [<a href="#B48-minerals-14-01288" class="html-bibr">48</a>] is shown for comparison. (for sample records refer to <a href="#app1-minerals-14-01288" class="html-app">Supplementary Table S2</a>).</p>
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<p>Histogram plots of &lt;600 Ma ages for (<b>a</b>–<b>c</b>) detrital zircons in the Keping area (for data see <a href="#app1-minerals-14-01288" class="html-app">Supplementary Tables S1 and S2</a>) and magmatic rocks from (<b>d</b>) the northwest margin of the Tarim Block, (<b>e</b>) the STOB, and (<b>f</b>) the YCTB (data sources: references [<a href="#B17-minerals-14-01288" class="html-bibr">17</a>,<a href="#B66-minerals-14-01288" class="html-bibr">66</a>,<a href="#B67-minerals-14-01288" class="html-bibr">67</a>]).</p>
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<p>Geochemical discriminant diagrams of sedimentary tectonic setting of Early-Guadalupian (squares are from the Balikelike Formation sandstone; round dots are from the Kalundaer Formation sandstone). (<b>a</b>) K<sub>2</sub>O/Na<sub>2</sub>O–SiO<sub>2</sub> diagram (after Roser (1986) [<a href="#B82-minerals-14-01288" class="html-bibr">82</a>]); (<b>b</b>) TiO<sub>2</sub>–TFe<sub>2</sub>O<sub>3</sub>+MgO diagram (after Bhatia (1983) [<a href="#B48-minerals-14-01288" class="html-bibr">48</a>]); (<b>c</b>) <span class="html-italic">F<sub>4</sub></span>–<span class="html-italic">F<sub>3</sub></span> diagram (after Roser (1988) [<a href="#B83-minerals-14-01288" class="html-bibr">83</a>]); (<b>d</b>) La/Th–Hf diagram (after Floyd (1987) [<a href="#B81-minerals-14-01288" class="html-bibr">81</a>]); (<b>e</b>) Th–Sc–Zr/10 diagram (after Bhatia (1986) [<a href="#B80-minerals-14-01288" class="html-bibr">80</a>]); (<b>f</b>) La–Th–Sc diagram (after Bhatia (1986) [<a href="#B80-minerals-14-01288" class="html-bibr">80</a>]). A-Oceanic island arc (OIA); B-continental island arc (CIA); C-active continental margin (ACM); D-passive continental margin (PM).</p>
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<p>Geochemical discriminant diagrams of the sedimentary tectonic setting from the Silurian to Mississippian. (<b>a</b>) K<sub>2</sub>O/Na<sub>2</sub>O–SiO<sub>2</sub> diagram (after Roser (1986) [<a href="#B82-minerals-14-01288" class="html-bibr">82</a>]); (<b>b</b>) <span class="html-italic">F<sub>4</sub></span>–<span class="html-italic">F<sub>3</sub></span> diagram (after Roser (1988) [<a href="#B83-minerals-14-01288" class="html-bibr">83</a>]); (<b>c</b>) La/Th–Hf diagram (after Floyd (1987) [<a href="#B81-minerals-14-01288" class="html-bibr">81</a>]). (Blue round dots are from Silurian samples; brown triangle dots are from Devonian sample; green squares are from Mississippian).</p>
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<p>Tectonic evolution model map of the northwest margin of the Tarim Block from the Early-late Devonian to the Guadalupian. (<b>a</b>) The period of the initial development of the foreland basins (the residual marine basin development stage); (<b>b</b>) The period of early foreland basin development; (<b>c</b>) The period of middle foreland basin development stage; (<b>d</b>) The late-stage foreland basin development; (<b>e</b>) The final stage of foreland basin development. (1. Tarim Block (TB), its pre-Carboniferous strata primarily composed of Silurian and Devonian clastic rocks, Cambrian and Ordovician carbonate rocks, and Precambrian crystalline basement rocks. 2. South Tianshan Block (STB). 3. Foreland basin sediment; 4. Seawater. 5. Direction of crustal movement. I. Wedge top. II. Foredeep. III. Forebulge. IV. Back-bulge. RSB. Remnant sea basin).</p>
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14 pages, 9124 KiB  
Article
Formation of the Liaotianshan Volcano in Southeastern China: Implications for the Evolution and Recharge of Crustal Magma System
by Boyun Shi, Lei Liu and Zengxia Zhao
Minerals 2024, 14(12), 1263; https://doi.org/10.3390/min14121263 - 12 Dec 2024
Viewed by 356
Abstract
Large-volume volcanic activity may offer significant insights into the evolution of silicic magma systems. The Liaotianshan volcano represents one of the earliest and best-preserved examples in SE China, comprising two stages of silicic volcanic rocks followed by extrusive rhyolite porphyries within the conduit. [...] Read more.
Large-volume volcanic activity may offer significant insights into the evolution of silicic magma systems. The Liaotianshan volcano represents one of the earliest and best-preserved examples in SE China, comprising two stages of silicic volcanic rocks followed by extrusive rhyolite porphyries within the conduit. In this study, we present petrological and geochemical analyses, along with zircon dating, of the Liaotianshan volcano. LA–ICP–MS zircon U–Pb dating results revealed that two-stage eruptions occurred between approximately 160 and 157 Ma, and the latest batch of magma was extruded from the conduit around 153 Ma. Volcanic rocks from both stages exhibit similar geochemical compositions, characterized by pronounced depletion in high-field-strength elements and enrichment in large-ion lithophile elements, with the majority of zircon εHf(t) values falling within a narrow range of –9.8 to –5.4. In contrast, the extrusive rhyolite porphyries display distinct geochemical characteristics, demonstrating enrichment in heavy rare earth elements relative to light rare earth elements [(La/Yb)N = 0.14–0.61], obvious negative Eu anomalies (Eu/Eu* = 0.01–0.03), and positive Ce anomalies, alongside markedly depleted zircon Hf isotopic compositions. We propose that the volcanic rocks from the two stages were formed by the reworking of the Paleoproterozoic crustal basement with occasional recharge of parental magma, while the extrusive rhyolite porphyries resulted from the mixing of crustal-derived magma and significantly depleted mantle-derived materials. The Liaotianshan volcano was formed in contradiction to the model of melt extraction and crystal accumulation within a magma chamber, instead reflecting the evolutionary history and replenishment dynamics of the crustal magma system. Full article
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Figure 1
<p>Distribution of Late Mesozoic volcanic–intrusive rocks in SE China (modified after [<a href="#B10-minerals-14-01263" class="html-bibr">10</a>]).</p>
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<p>(<b>a</b>) Geological map of the Liaotianshan volcano and sample locations (modified after [<a href="#B14-minerals-14-01263" class="html-bibr">14</a>]); (<b>b</b>) profile of the section from which the samples were collected. Notes: J<sub>1</sub><sup>Y</sup><span class="html-italic">ξγ</span><sup>C</sup>—early Jurassic biotite syenogranite; C<sub>1</sub><span class="html-italic">l</span>—lower Carboniferous Lindi Formation; P<sub>1</sub><span class="html-italic">c</span>—lower Permian Chuanshan Formation; P<sub>2</sub><span class="html-italic">q</span>—middle Permian Qixia Formation. The letters A, B, and C represent the end positions of the section profile in both (<b>a</b>,<b>b</b>).</p>
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<p>Representative photomicrographs of (<b>a,b</b>) the rhyolite porphyries from the volcanic conduit, (<b>c</b>,<b>d</b>) the second-stage lithic-bearing volcanic rocks, and (<b>e</b>,<b>f</b>) the first-stage crystal-rich volcanic rocks, respectively. Notes: Pl—plagioclase; Kfs—K-feldspar; Qtz—quartz.</p>
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<p>Cathodoluminescence images of representative zircons from the Liaotianshan volcano.</p>
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<p>Zircon U–Pb dating results for (<b>a</b>) extrusive rhyolite porphyry, (<b>b</b>–<b>g</b>) second-stage volcanic rocks, and (<b>h</b>) first-stage volcanic rock, respectively.</p>
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<p>Chondrite-normalized REE patterns for the zircons from (<b>a</b>) extrusive rhyolite porphyry, (<b>b</b>) second-stage volcanic rocks, and (<b>c</b>) first-stage volcanic rock, respectively (normalization values after [<a href="#B21-minerals-14-01263" class="html-bibr">21</a>]). Patterns of the inherited grains are not presented.</p>
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<p>Zircon Hf isotopic compositions of the Liaotianshan volcano and crustal basement materials [<a href="#B22-minerals-14-01263" class="html-bibr">22</a>]. The values of the extrusive rhyolite porphyry and first-stage volcanics are from [<a href="#B14-minerals-14-01263" class="html-bibr">14</a>].</p>
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<p>(<b>a</b>) Total alkali [<a href="#B23-minerals-14-01263" class="html-bibr">23</a>], (<b>b</b>) K<sub>2</sub>O, (<b>c</b>) Al<sub>2</sub>O<sub>3</sub>, and (<b>d</b>) Fe<sub>2</sub>O<sub>3</sub><sup>T</sup> vs. SiO<sub>2</sub> diagrams for rocks of the Liaotianshan volcano.</p>
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<p>(<b>a</b>) Chondrite-normalized REE patterns [<a href="#B21-minerals-14-01263" class="html-bibr">21</a>], and (<b>b</b>) primitive-mantle-normalized trace element variation diagram [<a href="#B24-minerals-14-01263" class="html-bibr">24</a>] for rocks of the Liaotianshan volcano.</p>
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<p>(<b>a</b>) (Sm/La)<sub>N</sub> vs. La, (<b>b</b>) Ti vs. Hf, (<b>c</b>) Th/U vs. Th and (<b>d</b>) Zr/Hf vs. Eu/Eu* variations in zircons of the Liaotianshan volcano.</p>
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<p>(<b>a</b>) Rb vs. Sr and (<b>b</b>) Ba vs. Eu/Eu* variations of extrusive and volcanic rocks from the Liaotianshan volcano, which are inconsistent with the melt extraction and residual cumulates model.</p>
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<p>Fluctuation in the SiO<sub>2</sub> contents of the volcanic rocks from the early to late parts of the volcano.</p>
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24 pages, 19611 KiB  
Article
Caledonian Sn Mineralization in the Yuechengling Granitic Batholith, South China: Geochronology, Geochemistry, Zircon Hf Isotopes, and Tourmaline Chemistry and B Isotopes of the Lijia Sn Deposit and Its Hosting Granites
by Yuhang Liu, Congcong Wang, Meng Feng, Yan Cui, Guicong Fang, Zuohai Feng, Wei Fu, Chuan Zhao and Chunzeng Wang
Minerals 2024, 14(12), 1243; https://doi.org/10.3390/min14121243 - 6 Dec 2024
Viewed by 522
Abstract
The Lijia Sn deposit, located in northeastern Guangxi Zhuang Autonomous Region of south China, occurs on the eastern margin of the Yuechengling granite batholith. The Sn deposit contains quartz vein type and greisen type ores and is spatially associated with the medium-coarse-grained biotite [...] Read more.
The Lijia Sn deposit, located in northeastern Guangxi Zhuang Autonomous Region of south China, occurs on the eastern margin of the Yuechengling granite batholith. The Sn deposit contains quartz vein type and greisen type ores and is spatially associated with the medium-coarse-grained biotite granite and the fine-grained tourmaline-bearing biotite granite. LA-ICP-MS zircon U-Pb dating gave an emplacement age of 431.7 ± 2.5 Ma for the medium-coarse-grained biotite granite and of 430.2 ± 2.4 Ma for the fine-grained tourmaline-bearing biotite granite. LA-ICP-MS cassiterite U-Pb dating yielded Tera-Wasserburg lower intercept ages of 429.1 ± 3.4 Ma and 425.7 ± 3.3 Ma for the quartz vein type and greisen type ores, respectively. The ages demonstrate near coeval Caledonian granitic emplacement and Sn mineralization events that have been considered uncommon in south China. Both granites might be derived from partial melting of the Paleoproterozoic basement, as evidenced from zircon ɛHf(t) values of −3.13 to −10.31 and TDM2 from 1627 Ma to 2134 Ma. Three different types of tourmalines have been identified, including (1) tourmaline in quartz–tourmaline nodules in the fine-grained tourmaline-bearing biotite granite (Tur 1), (2) tourmaline in quartz veins (Tur 2a), and (3) tourmaline in greisen (Tur 2b). Most of the tourmalines belong to the alkali group and the schorl-dravite solid-solution series. The hydrothermal tourmalines of Tur 2a and Tur2b showed similar δ11B values to those of the Tur 1 tourmalines in the fine-grained tourmaline-bearing biotite granite, suggesting ore-forming materials derived from granitic magmas. The hydrothermal tourmalines of Tur 2b had slightly lower δ11B values than Tur 1 and Tur 2a tourmalines as a result of progressive 11B depletion during early tourmaline crystallization. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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Graphical abstract

Graphical abstract
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<p>(<b>a</b>) Inset showing location of the study area in south China. (<b>b</b>) The Miao’ershan-Yuechengling granitic batholiths and the location of the Lijia Sn deposit in northeastern Guangxi [<a href="#B15-minerals-14-01243" class="html-bibr">15</a>,<a href="#B16-minerals-14-01243" class="html-bibr">16</a>].</p>
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<p>Simplified geological map (<b>a</b>) and cross sections (<b>b</b>) of the Lijia Sn deposit.</p>
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<p>Hand specimen photos (<b>a</b>–<b>d</b>), photomicrographs (<b>e</b>–<b>i</b>; cross-polarizing light), and back-scattered electron images (<b>j</b>–<b>l</b>) show characteristics of different types of granites and Sn ores of the Lijia Sn deposit. (<b>a</b>) The medium-coarse-grained biotite granite; (<b>b</b>) the fine-grained tourmaline-bearing biotite granite with tourmaline–quartz nodule; (<b>c</b>) the quartz vein type ore; (<b>d</b>) the greisen type ore; (<b>e</b>) the medium-coarse-grained biotite granite; (<b>f</b>) the fine-grained tourmaline-bearing biotite granite with euhedral-subhedral short prismatic tourmaline aggregates (Tur 1); (<b>g</b>) euhedral cassiterite co-exiting with needle-like or granular tourmaline (Tur 2a) and quartz in quartz vein type ore; (<b>h</b>) euhedral to subhedral cassiterite co-existing with plagioclase, sericite, and quartz in greisen type ore; (<b>i</b>) tourmaline (Tur 2a) in greisen as prismatic and radial aggregates and coexisting with quartz; (<b>j</b>) tourmaline (Tur 1) in tourmaline–quartz nodules; (<b>k</b>,<b>l</b>) tourmalines (Tur 2a and Tur 2b) in quartz vein and greisen. Pl—plagioclase; Kfs—K-feldspar; Bi-biotite; Tur—tourmaline; Cst—cassiterite; Ser—sericite; Ms—muscovite; Q—quartz.</p>
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<p>TIMA mineral phase maps of tourmaline in granite and Sn ores in the Lijia Sn deposit. (<b>a</b>) Tourmaline in the tourmaline–quartz nodules in the fine-grained tourmaline-bearing biotite granite; (<b>b</b>,<b>c</b>) tourmaline (Tur 1) coexists with quartz, albite, K-feldspar, muscovite, and chlorite; (<b>d</b>) tourmaline (Tur 2a) in the quartz vein coexists with cassiterite, muscovite, and quartz; (<b>e</b>,<b>f</b>) altered tourmaline (Tur 2a) and euhedral cassiterite in quartz vein, with secondary muscovite superimposing on tourmaline; (<b>g</b>) tourmaline (Tur 2b) in greisen coexists with scheelite, muscovite, and quartz; (<b>h</b>,<b>i</b>) scheelite and tourmaline (Tur 2b) in greisen.</p>
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<p>Molar A/NK vs. molar A/CNK diagram of granite in the Lijia Sn deposit. Red dots show the medium-coarse-grained biotite granite; blue dots show the fine-grained tourmaline-bearing biotite granite.</p>
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<p>Harker diagrams for the granites in the Lijia Sn deposit. The whole-rock major elemental compositions have been recalculated to 100% on a volatile-free basis.</p>
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<p>Primitive mantle-normalized trace element spidergram (<b>a</b>) and chondrite-normalized REE patterns (<b>b</b>) of the medium-coarse-grained biotite granite and the fine-grained tourmaline-bearing biotite granite. The normalization values for primitive mantle and chondrite are from [<a href="#B48-minerals-14-01243" class="html-bibr">48</a>].</p>
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<p>CL images and U-Pb concordia plots of zircon crystals from the medium-coarse-grained biotite granite (<b>a</b>,<b>b</b>) and the fine-grained tourmaline-bearing biotite granite (<b>c</b>,<b>d</b>).</p>
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<p>Cassiterite CL images (<b>a</b>,<b>b</b>), U-Pb isochron diagrams (<b>c</b>,<b>e</b>), and concordia diagrams (Ter-Wasserburg) (<b>d</b>,<b>f</b>) (samples YCL1908 and YCL1909).</p>
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<p>Histograms of zircon εHf(t) values and TDM<sub>2</sub> (Ga) for the medium-coarse-grained biotite granite (<b>a</b>,<b>b</b>) and the fine-grained tourmaline-bearing biotite granite (<b>c</b>,<b>d</b>).</p>
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<p>(<b>a</b>) Classification of Lijia tourmalines based on X-site occupancy after [<a href="#B49-minerals-14-01243" class="html-bibr">49</a>]; (<b>b</b>) Al-Fe-Mg ternary diagram showing compositional variations of tourmaline from the Lijia granites and ores. 1. Li-rich granitoids and associated pegmatites and aplites; 2. Li-poor granitoids and associated pegmatites and aplites; 3, Fe<sup>3+</sup>-rich quartz-tourmaline rocks (hydrothermally altered granites); 4. Metapelites and meta-psammites coexisting with an Al-saturated phase; 5. Metapelites and meta-psammites not coexisting with an Al-saturated phase; 6. Fe<sup>3+</sup>-rich quartz-tourmaline rocks, calc-silicate rocks, and metapelites; 7. Low Ca meta-ultramafics and Cr- and V-rich metasediments; 8. Meta-carbonates and meta-pyroxenites [<a href="#B50-minerals-14-01243" class="html-bibr">50</a>].</p>
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<p>(<b>a</b>) Fe/(Fe+Mg) vs. Na/(Na+Ca) diagram for classification of tourmaline; (<b>b</b>) plot of Mg vs. Fe of cation occupancies in tourmalines. Same symbols as in <a href="#minerals-14-01243-f011" class="html-fig">Figure 11</a>.</p>
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<p>Percentile box−and−whisker plots showing comparisons of trace elements in tourmalines from the Lijia granite and Sn ores.</p>
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<p>Boron isotopic compositions of tourmaline measured using in situ LA−MC−ICP−MS.</p>
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<p>Plot of ages vs. ɛHf(t) of the Yuechengling granites. The field for Paleoproterozoic basement in Cathaysia block is from [<a href="#B62-minerals-14-01243" class="html-bibr">62</a>,<a href="#B63-minerals-14-01243" class="html-bibr">63</a>,<a href="#B64-minerals-14-01243" class="html-bibr">64</a>].</p>
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<p>(<b>a</b>) Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> vs. CaO/Na<sub>2</sub>O diagram and (<b>b</b>) Rb/Sr vs. Rb/Ba diagram for the Yuechengling granites. The mixing curve between the basalt- and pelite-derived melts in (<b>a</b>,<b>b</b>) is from [<a href="#B65-minerals-14-01243" class="html-bibr">65</a>]. The outlined field of partial melts is from [<a href="#B66-minerals-14-01243" class="html-bibr">66</a>] and references therein.</p>
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<p>Measured boron isotope composition as function of host rock type and inferred B sources (modified after [<a href="#B88-minerals-14-01243" class="html-bibr">88</a>]).</p>
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<p>(<b>a</b>) Sn vs. Zn/Nb diagram and (<b>b</b>) Sn vs. Co/Nb diagram for tourmaline from the Lijia Sn deposit (base map after [<a href="#B19-minerals-14-01243" class="html-bibr">19</a>]).</p>
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20 pages, 21100 KiB  
Article
Petrogenesis and Metallogenic Significance of the Demingding Mo-Cu Porphyry Deposit in the Gangdese Belt, Xizang: Insights from U-Pb and Re-Os Geochronology and Geochemistry
by Sudong Shi, Shuyuan Chen, Sangjiancuo Luo, Huan Ren and Xiaojia Jiang
Minerals 2024, 14(12), 1232; https://doi.org/10.3390/min14121232 - 3 Dec 2024
Viewed by 535
Abstract
The 1500 km-long Gangdese magmatic belt is a crucial region for copper polymetallic mineralization, offering valuable insights into collisional porphyry copper systems. This study focuses on the Demingding deposit, a newly identified occurrence of molybdenum–copper (Mo-Cu) mineralization within the eastern segment of the [...] Read more.
The 1500 km-long Gangdese magmatic belt is a crucial region for copper polymetallic mineralization, offering valuable insights into collisional porphyry copper systems. This study focuses on the Demingding deposit, a newly identified occurrence of molybdenum–copper (Mo-Cu) mineralization within the eastern segment of the belt. While the mineralization age, magmatic characteristics, and tectonic context are still under investigation, we examine the deposit’s petrology, zircon U-Pb geochronology, whole-rock chemistry, and Re-Os isotopic data. The Demingding deposit exhibits a typical alteration zoning, transitioning from an inner potassic zone to an outer propylitic zone, which is significantly overprinted by phyllic alteration closely associated with Mo and Cu mineralization. Zircon U-Pb dating of the ore-forming monzogranite porphyries reveals crystallization ages ranging from 21 to 19 Ma, which is indistinguishable within error from the mean Re-Os age of 21.3 ± 0.4 Ma for Mo veins and veinlets hosted by these porphyries. This alignment suggests a late Miocene magmatic event characterized by Mo-dominated mineralization, coinciding with the continuous thickening of the continental crust during the collision of the Indian and Asian continents. The ore-forming porphyries range in composition from granodiorite to monzogranite and are classified as high-K calc-alkaline with adakite-like features, primarily resulting from the partial melting of subduction-modified thickened mafic lower crust. Notably, the ore-forming porphyries exhibit higher fO2 and H2O levels than barren porphyries in this area during crustal thickening, highlighting the significant contributions of hydrous and oxidized fluids from their source to the Mo-Cu mineralization process. Regional data indicate that the Gangdese porphyry metallogenic belt experienced concentrated Cu-Mo mineralization between 17 and 13 Ma. The formation of Mo-dominated deposits such as Demingding and Tangbula in the eastern segment of the belt, with slightly older ages around 20 Ma, underscores the presence of a significant porphyry Mo metallogenic event during this critical post-collision mineralization period. Full article
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<p>Simplified geologic map of Xizang (<b>a</b>) and map showing the simplified tectonic and regional geologic setting of the Gangdese magmatic belt (<b>b</b>) (modified after Lin et al., 2024 [<a href="#B21-minerals-14-01232" class="html-bibr">21</a>]).</p>
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<p>Simplified geological map (<b>a</b>) and cross-section (<b>b</b>,<b>c</b>) of the Demingding Mo-Cu deposit (modified after Ren et al., 2024 [<a href="#B37-minerals-14-01232" class="html-bibr">37</a>]).</p>
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<p>Hand-specimen photographs of the porphyries and Mo-Cu mineralization from the Demingding Mo-Cu deposit. (<b>a</b>) The exposed location of the ore body shows the rock with red alteration. (<b>b</b>,<b>c</b>) Monzogranite porphyry; (<b>d</b>) Widely developed quartz veins in the granite porphyry; (<b>e</b>–<b>h</b>) Monzogranite porphyry with chalcopyrite and molybdenite mineralization.</p>
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<p>Photomicrographs of ore-forming porphyries with mineral assemblages of quartz, biotite, plagioclase, and K-feldspar. (<b>a</b>) Euhedral to subhedral quartz occurs as phenocrysts in the ore-bearing porphyry; (<b>b</b>,<b>c</b>) The phenocrysts in the ore-bearing porphyry are mainly composed of euhedral to subhedral quartz, plagioclase, biotite, and K-feldspar; (<b>d</b>) A small amount of feldspar has been altered to epidote. Abbreviations: Qz-Quartz; Kfs-K-feldspar; Pl-plagioclase; Bi-biotite.</p>
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<p>Representative photomicrographs of mineralization and alteration from the Demingding Mo-Cu deposit. (<b>a</b>–<b>c</b>) Magnetite and biotite from the potassic alteration stage; (<b>d</b>,<b>e</b>) Quartz + biotite + Cu-Fe sulfides vein in the potassic alteration stage; (<b>f</b>) Sericite intergrow with Cu-Fe sulfides in the phyllic alteration; (<b>g</b>) Chlorite-calcite veins occurred during the propylitic zone; (<b>h</b>,<b>i</b>) Chalcopyrite-quartz vein in the ore-forming porphyries; (<b>j</b>–<b>l</b>) Disseminated chalcopyrite and molybdenite in the ore-forming porphyries. The dashed lines represent the boundaries of the vein in the figure.</p>
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<p>Cathodoluminescence images for representative zircon grains from (<b>a</b>) the 25,053 sample, (<b>b</b>) the 25,028 sample, (<b>c</b>) the ZK005-596.35 sample, and (<b>d</b>) the DMD17 sample in the Demingding rhyolite porphyries and monzogranite porphyries.</p>
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<p>Zircon U-Pb concordia diagrams and mean age for the Demingding rhyolite porphyries and monzogranite porphyries.</p>
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<p>(Ce/Nd)/Y vs. 10,000*(Eu/Eu*)/Y (<b>a</b>) and (Ce/Nd)/Y vs. Eu/Eu* (<b>b</b>) diagrams for the Demingding rhyolite porphyries and monzogranite porphyries (modified after Lu et al., 2016 [<a href="#B48-minerals-14-01232" class="html-bibr">48</a>]).</p>
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<p>Temperatures (<b>a</b>), ∆FMQ (<b>b</b>), and H<sub>2</sub>O contents (<b>c</b>) of Demingding rhyolite porphyries and monzogranite porphyries.</p>
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<p>(<b>a</b>) (K<sub>2</sub>O + Na<sub>2</sub>O) vs. SiO<sub>2</sub> diagram (Middlemost, 1994) [<a href="#B49-minerals-14-01232" class="html-bibr">49</a>]; (<b>b</b>) SiO<sub>2</sub> vs. K<sub>2</sub>O diagram (Roberts and Clemens, 1993) [<a href="#B50-minerals-14-01232" class="html-bibr">50</a>]; (<b>c</b>) Sr/Y vs. Y diagram; (<b>d</b>) (La/Yb)<sub>N</sub> vs. (Yb)<sub>N</sub> diagram.</p>
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<p>Chondrite-normalized REE pattern (<b>a</b>) and primitive mantle-normalized spidergram (<b>b</b>) for the rhyolite porphyries and monzogranite porphyries. Data are normalized by values of chondrite and primitive mantle (Sun and McDonough 1989) [<a href="#B51-minerals-14-01232" class="html-bibr">51</a>].</p>
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<p>Molybdenite Re–Os isochron and weighted mean model age plots of the Mo veins and veinlets hosted in these porphyries.</p>
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<p>Dy/Yb vs. SiO<sub>2</sub> diagram of Demingding rhyolite porphyries and monzogranite porphyries.</p>
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<p>Image illustrating the genetic and geodynamic model for the monzogranite porphyries in the Demingding porphyry Mo -Cu deposit.</p>
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22 pages, 14163 KiB  
Article
Petrogenesis of Permian Granodiorite and Diorite in Eastern Jilin Province and Its Constraints on the Late-Stage Evolution of the Paleo-Asian Ocean
by Yao Tang, Deyou Sun, Changzhou Deng, Jun Gou, Changliang Fu and Dongguang Yang
Minerals 2024, 14(12), 1223; https://doi.org/10.3390/min14121223 - 30 Nov 2024
Viewed by 421
Abstract
The Solonker-Xar Moron-Changchun-Yanji Suture Zone is the result of the final closure of the Paleo-Asian Ocean (PAO). However, the closure time of the PAO in Northeast China remains controversial. The Hunchun area is located in the easternmost part of the Solonker-Xar Moron-Changchun-Yanji Suture [...] Read more.
The Solonker-Xar Moron-Changchun-Yanji Suture Zone is the result of the final closure of the Paleo-Asian Ocean (PAO). However, the closure time of the PAO in Northeast China remains controversial. The Hunchun area is located in the easternmost part of the Solonker-Xar Moron-Changchun-Yanji Suture Zone. Tectonism and magmatism in the Hunchun area can provide important information for understanding the late-stage evolution of the PAO. In this study, our zircon U-Pb ages show that the granodiorites and diorites in the Hunchun were formed at 282.3–251.4 Ma. This geochronological evidence suggests prolonged Permian magmatism in the Hunchun area. Whole-rock geochemistry, zircon trace, and Lu-Hf isotope data show that all the intrusive rocks are mainly calc-alkaline series to arc tholeiite series. Granodiorites are I-type granites formed by the partial melting of juvenile lower crust derived from the mantle. Diorites show similar characteristics to the sanukitic high-Mg diorite and are formed by the partial melting of the depleted mantle metasomatized by subduction sediments and/or slab-derived fluids. These results indicate that the Permian diorites and granodiorites in the Hunchun area formed in an active continental margin setting related to the subduction of the PAO plate. Significantly, sudden changes in the whole-rock Sr/Y and (La/Yb)N ratios and zircon εHf(t) values are observed in the Late Permian-Early Triassic igneous rocks in the eastern Central Asian Orogenic Belt (CAOB). This indicates that the final closure of the PAO in Northeast China likely occurred in the Late Permian-Early Triassic. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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Figure 1
<p>(<b>a</b>). Tectonic sketch map showing the main subdivisions of central and eastern Asia and location of the study area (modified from Long et al. [<a href="#B18-minerals-14-01223" class="html-bibr">18</a>]), EB = Ergunan Block, XB = Xing’an Block, JB = Jiamusi Block, NCC = North China Block, KB = Khanka Block, NMB = Nadanhada Micro-block, SZB = Songnen-Zhangguangcailing Block, XXS = Xinlin-Xiguitu Suture, HHS = Heihe-Hegenshan Suture, MYS = Mudanjiang-Yilan Suture, SXCYS = Solonker-Xar Moron- Changchun-Yanji Suture, MOS = Mongol–Okhotsk Suture, PAS = Paleo-Asian Suture; (<b>b</b>) Simplified geological map of the eastern CAOB showing the distribution of Paleozoic-Mesozoic granitoids (modified from Jiang et al. [<a href="#B19-minerals-14-01223" class="html-bibr">19</a>]); (<b>c</b>) Regional geological map of the Hunchun area and sampling location.</p>
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<p>(<b>a</b>–<b>d</b>). Field and microscope photos of the intrusive rocks in the study area: (<b>a,b</b>) red dotted lines show the intrusive contact relationship between granodiorite and diorite; (<b>c</b>) Red dashed areas are diorite inclusions in granodiorite. (<b>e,f</b>) Representative photomicrographs showing the texture of the intrusive rocks from the Hunchun area: (<b>e</b>) Granodiorite from sample 1390-1; (<b>f</b>) Diorite from sample 1379-3. Abbreviations: Q, quartz; Pl, plagioclase; Kf, Alkaline feldspar; Bi, biotite; Hb, hornblende.</p>
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<p>Representative CL images and U-Pb concordia diagrams of zircons from the studied plutonic rocks in the Hunchun area. The red circles represent the position of the dating spots respectively, which are all 30 μm in diameter.</p>
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<p>(<b>a</b>). Total alkali versus silica classification plot [<a href="#B34-minerals-14-01223" class="html-bibr">34</a>]. The line between alkaline and sub-alkaline series is from [<a href="#B35-minerals-14-01223" class="html-bibr">35</a>]; (<b>b</b>) SiO<sub>2</sub> versus K<sub>2</sub>O diagram showing shoshonitic, high-K calc-alkaline series, Calc-alkaline series and Arc tholeiite series fields [<a href="#B36-minerals-14-01223" class="html-bibr">36</a>]; (<b>c</b>) Molar A/CNK versus molar A/NK plot showing the metaluminous to slightly peraluminous nature of the studied intrusive bodies. A/CNK, molar Al<sub>2</sub>O<sub>3</sub>/(CaO+Na<sub>2</sub>O+K<sub>2</sub>O); A/NK, molar Al<sub>2</sub>O<sub>3</sub>/(Na<sub>2</sub>O+K<sub>2</sub>O). The gray diamond and circular symbols represent the data of granodiorites and diorites published by predecessors in the Hunchun area and refer to [<a href="#B20-minerals-14-01223" class="html-bibr">20</a>] and [<a href="#B6-minerals-14-01223" class="html-bibr">6</a>].</p>
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<p>(<b>a,b</b>). Chondrite-normalized rare earth element plots, normalizing values are from [<a href="#B37-minerals-14-01223" class="html-bibr">37</a>]; (<b>c,d</b>) Primitive mantle-normalized trace element diagrams for the studied Plutonic rocks, normalizing values are from [<a href="#B38-minerals-14-01223" class="html-bibr">38</a>]. The gray circular symbols represent the data of diorite published by predecessors in the Hunchun area, respectively, and refer to [<a href="#B20-minerals-14-01223" class="html-bibr">20</a>]. (<b>e</b>). Chondrite-normalized zircon REE diagram for the studied plutonic rocks. Normalizing values are from [<a href="#B37-minerals-14-01223" class="html-bibr">37</a>]. Shaded areas represent the 5–95 percentile range for each sample group. The signed line refers to the median value for each group. The gray-shaded area is the studied continental arc granite area from [<a href="#B33-minerals-14-01223" class="html-bibr">33</a>].</p>
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<p>(<b>a</b>). Magmatic vs. hydrothermal zircon discrimination diagram, La vs. (Sm/La)<sub>N</sub> plot suggesting that most analyzed grians are magmatic and have not been affected by post-crystallization hydrothermal alteration. Magmatic and hydrothermal fields are from (Hoskin, 2005) [<a href="#B41-minerals-14-01223" class="html-bibr">41</a>]; (<b>b</b>) The Th + U vs. (La/Gd)<sub>N</sub> plot suggests that no metamict zircon grains are present in the studied rocks. Actinide concentration is a proxy for lattice damage induced by radiation [<a href="#B42-minerals-14-01223" class="html-bibr">42</a>]. (<b>c</b>,<b>d</b>) Zircon trace petrogenesis classification diagrams: (<b>c</b>) log(Ce/U) vs. log(Th/U) plot of Roberts et al. (2024) [<a href="#B43-minerals-14-01223" class="html-bibr">43</a>]; (<b>d</b>) (Ce/Nd)<sub>N</sub> vs. Th/U plot of Sawaki et al. [<a href="#B44-minerals-14-01223" class="html-bibr">44</a>].</p>
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<p>Whole-rock bivariate diagrams: (<b>a</b>) Zr+Nb+Ce+Y vs. (K<sub>2</sub>O+Na<sub>2</sub>O)/CaO diagram [<a href="#B46-minerals-14-01223" class="html-bibr">46</a>], FG, fractionated felsic granites; OGT, unfractionated M-, I- and S-type granites; A, A-type granite. (<b>b</b>) SiO<sub>2</sub> vs. P<sub>2</sub>O<sub>5</sub> I- &amp; S-type discrimination diagram [<a href="#B15-minerals-14-01223" class="html-bibr">15</a>]; (<b>c</b>) Y vs. Sr/Y plot showing petrogenesis for HMAs [<a href="#B48-minerals-14-01223" class="html-bibr">48</a>,<a href="#B49-minerals-14-01223" class="html-bibr">49</a>], HMA, High-Mg andesite; (<b>d</b>) Th/Yb vs. Ba/La diagram illustrating slab-derived fluids and sediment-melt contributions to the magmatic source [<a href="#B33-minerals-14-01223" class="html-bibr">33</a>]. The gray diamond and circular symbols represent the data of granodiorites and diorites published by predecessors in the Hunchun area, respectively, and refer to [<a href="#B20-minerals-14-01223" class="html-bibr">20</a>] and [<a href="#B6-minerals-14-01223" class="html-bibr">6</a>].</p>
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<p>(<b>a</b>). Sr/Y vs. Y diagram discriminating between adakitic and classical island arc [<a href="#B48-minerals-14-01223" class="html-bibr">48</a>]; (<b>b</b>) Plutonic rocks crystallization temperature box plot. Temperature is calculated based on the Ti content according to Watson et al. [<a href="#B53-minerals-14-01223" class="html-bibr">53</a>]. (<b>c</b>,<b>d</b>) Whole-rock discriminant diagrams: (<b>c</b>) Rb–Hf–Ta discrimination diagram [<a href="#B56-minerals-14-01223" class="html-bibr">56</a>] and (<b>d</b>) Y+Nb vs. Rb discrimination diagram [<a href="#B57-minerals-14-01223" class="html-bibr">57</a>] of tectonic setting. Abbreviations: VAG, volcanic arc granites; syn-COLG, syn-collision granites; post-COLG, post-collision granites; WPG, within plate granites; ORG, Ocean Ridge Granites. The gray diamond and circular symbols represent the data of granodiorites and diorites published by predecessors in the Hunchun area, respectively, and refer to [<a href="#B20-minerals-14-01223" class="html-bibr">20</a>] and [<a href="#B6-minerals-14-01223" class="html-bibr">6</a>].</p>
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<p>(<b>a</b>). Zircon Hf vs. U/Yb tectonic discrimination diagrams for the studied intrusive rocks. Mid-ocean ridge (MORB-type), ocean island (OI-type), continental arc (Cont. Arc-type), and post-collisional fields are from [<a href="#B39-minerals-14-01223" class="html-bibr">39</a>]. The dashed line distinguishes the mantle from the crust; (<b>b</b>) log (Nb/Yb) vs. log (U/Yb) diagram [<a href="#B39-minerals-14-01223" class="html-bibr">39</a>]. The shaded band represents a “mantle-zircon array”.</p>
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<p>Zircon plots of (<b>a</b>) Hf vs. Ti, (<b>b</b>) Hf vs. Y, and (<b>c</b>) Hf vs. U for the studied intrusive rocks [<a href="#B55-minerals-14-01223" class="html-bibr">55</a>].</p>
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<p>(<b>a</b>,<b>b</b>). ε<sub>Hf</sub>(t)-t evolution diagram of the studied intrusive rocks. The shaded field represents the tectonic transitional period with a considerable isotopic variation (for details, see text). (<b>c</b>,<b>d</b>) Whole-rock (<b>c</b>) t-Sr/Y and (<b>d</b>) t-(La/Yb)<sub>N</sub> correlations with crustal thickness for the studied subduction-related volcanic arcs, estimated crustal thickness calculated based on [<a href="#B52-minerals-14-01223" class="html-bibr">52</a>]. La/Yb ratios are normalized to chondritic values. Shaded areas represent collision phases. The gray diamond and circular symbols represent the data of granites and diorites published by predecessors and refer to [<a href="#B20-minerals-14-01223" class="html-bibr">20</a>], Yang, and [<a href="#B58-minerals-14-01223" class="html-bibr">58</a>]. These granite data are all located in the Changchun-Yanji Suture. CHUR: Chondrite-Uniform Reservoir.</p>
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<p>Zircon bivariate diagrams for the studied intrusive rocks in: (<b>a</b>) Ce/Ce* vs. Eu/Eu* and (<b>b</b>) Hf vs. Ce/Ce*. Gray arc granite area is from zircon data by [<a href="#B33-minerals-14-01223" class="html-bibr">33</a>]. An increase in Ce/Ce* and Eu/Eu* ratios indicates higher magmatic oxygen fugacity. Figure (<b>a</b>) illustrates that granodiorite samples formed in a relatively stable environment with consistently high oxygen fugacity, whereas diorite samples reflect higher but variable oxygen fugacity. Figure (<b>b</b>) depicts the variations in oxygen fugacity throughout magmatic evolution, highlighting the fluctuating oxygen fugacity during the crystallization of the diorite samples for details in [<a href="#B55-minerals-14-01223" class="html-bibr">55</a>].</p>
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<p>Schematic diagram of the formation for the studied Permian intrusive rocks in the Hunchun area of Jilin Province (modified from [<a href="#B73-minerals-14-01223" class="html-bibr">73</a>]): (<b>a</b>) Paleo-Asian Ocean Subduction in Hunchun area during Permian; (<b>b</b>) The closure of the Paleo-Asian Ocean in Hunchun area during Late Permian to Early Triassic. Abbreviations: SZB, Songnen-Zhangguangcailing Block; SCXYS, Solonker-Xar Moron-Changchun-Yanji Suture.</p>
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17 pages, 7567 KiB  
Article
Temperature Controls Initial REE Enrichment in Peraluminous Granites: Implication from the Parent Granites in the Shangyou Ion-Adsorption Type REE Deposit
by Jiaohua Zou, Chongwen Xu, Qinghe Yan and Jiang Zhu
Minerals 2024, 14(12), 1222; https://doi.org/10.3390/min14121222 - 29 Nov 2024
Viewed by 562
Abstract
The initial enrichment of rare earth elements (REE) in granites plays an important role for the generation of ion-adsorption type REE deposits. It has been summarized that the mineralization-related granitoids are mostly peraluminous, but the enrichment mechanism of REE in this peraluminous granite [...] Read more.
The initial enrichment of rare earth elements (REE) in granites plays an important role for the generation of ion-adsorption type REE deposits. It has been summarized that the mineralization-related granitoids are mostly peraluminous, but the enrichment mechanism of REE in this peraluminous granite is currently not well understood. In this study, we conducted geochronology, petrological, and geochemical investigations on the biotite granite and muscovite granite from the Shangyou complex in Ganzhou, Jiangxi Province. Zircon U-Pb dating indicates that both the biotite granite and muscovite granite generated in the Early Silurian (ca. 433–434 Ma). The high aluminum saturation index and occurrence of muscovite and old zircon cores indicate that they belong to the S-type granite and are derived from the melting of metagreywacke. The relatively higher FeOT contents, Mg# values, and zirconium saturation temperatures (760–873 °C) for the biotite granite resulted from hydrous melting with the involvement of mantle material. In contrast, the muscovite granite with low FeOT contents, Mg# values, Nb/Ta ratios, and zirconium saturation temperatures (748–761 °C) indicates a purely crust-derived melt formed by muscovite dehydration melting. There is a positive correlation of REE contents with the formation temperature and Th contents in both the Shangyou granites and the data collected from global peraluminous granites. This indicates that temperature plays a key role in the REE enrichment in peraluminous granites, as the high-temperature condition could promote the melting of REE-rich and Th-rich accessory minerals of allanite and REE-phosphate and result in the increases in both REE contents and Th contents in the melts. Given the fact that the parent granites for ion-adsorbing REE deposits are mostly peraluminous and generated in the extensional setting in South China, we concluded that peraluminous granite formed under high-temperature extensional tectonic settings favors initial REE enrichment, which further contributes to the formation of ion-adsorbing REE deposits in South China. Full article
(This article belongs to the Section Mineral Deposits)
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<p>(<b>a</b>) The distributions of granitoids and ion-adsorbing REE deposits in South China [<a href="#B3-minerals-14-01222" class="html-bibr">3</a>,<a href="#B30-minerals-14-01222" class="html-bibr">30</a>]; (<b>b</b>) Simplified geological map of the Shangyou pluton.</p>
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<p>Photomicrographs of the granites from Shangyou pluton. (<b>a</b>): biotite granite; (<b>b</b>): schlieren in the biotite granite; (<b>c</b>): muscovite monzogranite; (<b>d</b>): muscovite enclosed by albite. Q: quartz; Kf: K-feldspar; Pl: plagioclase; Bi: biotite; Ap: apatite; Mus: muscovite.</p>
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<p>U-Pb dating for the (<b>a</b>,<b>b</b>) Shangyou biotite granite and (<b>b</b>–<b>d</b>) muscovite granite.</p>
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<p>(<b>a</b>) TAS [<a href="#B36-minerals-14-01222" class="html-bibr">36</a>] and (<b>b</b>) A/CNK vs. A/NK [<a href="#B37-minerals-14-01222" class="html-bibr">37</a>] diagrams for the Shangyou biotite granite and muscovite monzogranite.</p>
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<p>Harker diagrams for the Shangyou biotite granite and muscovite monzogranite.</p>
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<p>Chondrite-normalized REE patterns (<b>a</b>) and primitive mantle-normalized trace element patterns (<b>b</b>) for the Shangyou biotite granite and muscovite monzogranite. Chondrite and primitive mantle data from Sun et al. (1989) [<a href="#B38-minerals-14-01222" class="html-bibr">38</a>].</p>
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<p>Zr + Nb + Ce + Y vs. K<sub>2</sub>O + Na<sub>2</sub>O)/CaO [<a href="#B40-minerals-14-01222" class="html-bibr">40</a>] (<b>a</b>) and ACF classification [<a href="#B40-minerals-14-01222" class="html-bibr">40</a>] (<b>b</b>) diagrams of the Shangyou biotite granite and muscovite monzogranite.</p>
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<p>Discrimination diagrams of source region of (<b>a</b>) Al<sub>2</sub>O<sub>3</sub> + MgO + TiO<sub>2</sub> + FeO<sup>T</sup> vs. Al<sub>2</sub>O<sub>3</sub>/(MgO + TiO<sub>2</sub> + FeO<sup>T</sup>), and (<b>b</b>) CaO + MgO + TiO<sub>2</sub> + FeO<sup>T</sup> vs. CaO/(MgO + TiO<sub>2</sub> + FeO<sup>T</sup>) for Shangyou biotite granite and muscovite monzogranite (after Douce, 1999 [<a href="#B49-minerals-14-01222" class="html-bibr">49</a>]).</p>
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<p>(<b>a</b>) Na<sub>2</sub>O/K<sub>2</sub>O vs. FeO<sup>T</sup> [<a href="#B61-minerals-14-01222" class="html-bibr">61</a>] and (<b>b</b>) SiO<sub>2</sub> vs. Mg# [<a href="#B62-minerals-14-01222" class="html-bibr">62</a>] diagrams for Shangyou biotite granite and muscovite monzogranite.</p>
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<p>TZr (<b>a</b>), Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> (<b>b</b>), and Th (<b>c</b>) vs. REE plots of the Shangyou biotite granite and muscovite monzogranite and peraluminous granitoids from worldwide. The data for global peraluminous granitoids are from Georoc: “<a href="http://georoc.mpch-mainz.gwdg.de/georoc" target="_blank">http://georoc.mpch-mainz.gwdg.de/georoc</a> (accessed on 12 June 2024)”.</p>
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21 pages, 20991 KiB  
Article
Petrogenesis of Diorite-Porphyrite in the Southern Xintai Area of the Mid-Western Shandong Peninsula, North China Craton: Insights from Geochronology, Mineralogy, Geochemistry, and Sr-Nd-Hf Isotopes
by Lijie Jin, Jilin Wang, Pinrui Qin, Chunjia Li, Shuang Xu, Zhixin Han, Wei Wang, Wei Liu, Zisheng Wang, Jilei Gao and Fangfang Li
Minerals 2024, 14(12), 1220; https://doi.org/10.3390/min14121220 - 29 Nov 2024
Viewed by 453
Abstract
The Early Cretaceous intermediate intrusive rocks have important significance in understanding the crust–mantle interaction, iron mineralization, and tectonic evolution in the western Shandong Peninsula. In this study, we present new zircon U–Pb ages, and Hf isotope, whole-rock geochemistry, Sr–Nd isotopes, and the mineral [...] Read more.
The Early Cretaceous intermediate intrusive rocks have important significance in understanding the crust–mantle interaction, iron mineralization, and tectonic evolution in the western Shandong Peninsula. In this study, we present new zircon U–Pb ages, and Hf isotope, whole-rock geochemistry, Sr–Nd isotopes, and the mineral chemistry of the diorite-porphyrite in the southern Xintai area, mid-western Shandong Peninsula. The diorite-porphyrite formed at ca. 125 Ma. They have intermediate SiO2 (59.57–62.29 wt.%) and MgO (2.78–3.58 wt.%) contents, high Mg# values (53–56), high Sr (589–939 ppm) and low Y (9.2–10.8 ppm) contents, and high Sr/Y ratios (54–94), showing adakitic affinity. The diorite-porphyrite exhibits lower zircon εHf(t) values (−30.1 to 7.5) and whole-rock εNd(t) values (−3.5 to −6.0), with (87Sr/86Sr)i ratios of 0.70514–0.70567. We suggest that the diorite-porphyrite was derived from the partial melting of the local delamination of lower continental crust and then by the interaction with the enriched lithospheric mantle. The genesis of diorite-porphyrite may be related to the rollback process of the Paleo-Pacific slab in the Early Cretaceous. This geodynamic process induced the melting of the enriched lithospheric mantle, subducted oceanic crust, and local delamination of lower continental crust, which produced different types of adakitic magmatism in the western Shandong Peninsula. Full article
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<p>(<b>a</b>) Tectonic subdivision of the NCC (after [<a href="#B43-minerals-14-01220" class="html-bibr">43</a>]). (<b>b</b>) Simplified geological map of Shandong Peninsula (after [<a href="#B27-minerals-14-01220" class="html-bibr">27</a>]). (<b>c</b>) Geological sketch map of the southern Xintai area of the mid-western Shandong Peninsula.</p>
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<p>Representative photographs and photomicrographs of diorite-porphyrite in the Xintai area. (<b>a</b>) The diorite-porphyrite intruded into the Lower Cambrian Mantou Formation; (<b>b</b>,<b>c</b>) Field photographs of diorite-porphyrite; (<b>d</b>,<b>e</b>) SEM images of porphyritic texture in diorite-porphyrite; (<b>f</b>) Representative plagioclase phenocryst in cross-polarized light.</p>
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<p>Typical zircon CL images and zircon U–Pb concordia diagrams of diorite-porphyrite.</p>
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<p>Diagrams of (<b>a</b>) (K<sub>2</sub>O + Na<sub>2</sub>O) versus SiO<sub>2</sub> (TAS; [<a href="#B56-minerals-14-01220" class="html-bibr">56</a>]); (<b>b</b>) SiO<sub>2</sub> versus K<sub>2</sub>O [<a href="#B57-minerals-14-01220" class="html-bibr">57</a>]; A/CNK versus A/NK [<a href="#B58-minerals-14-01220" class="html-bibr">58</a>]. (<b>c</b>) Data sources: Adakitic rocks from Tiezhai [<a href="#B22-minerals-14-01220" class="html-bibr">22</a>]; Mengyin and Liujing [<a href="#B33-minerals-14-01220" class="html-bibr">33</a>]; Mafic intrusive rocks [<a href="#B11-minerals-14-01220" class="html-bibr">11</a>]; Laiwu ore-related intrusive rocks [<a href="#B55-minerals-14-01220" class="html-bibr">55</a>].</p>
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<p>Variation in (<b>a</b>) MgO, (<b>b</b>) Fe<sub>2</sub>O<sub>3</sub><sup>T</sup>, (<b>c</b>) CaO, (<b>d</b>) Na<sub>2</sub>O, (<b>e</b>) TiO<sub>2</sub>, (<b>f</b>) Al<sub>2</sub>O<sub>3</sub>, (<b>g</b>) K<sub>2</sub>O, and (<b>h</b>) P<sub>2</sub>O<sub>5</sub> versus SiO<sub>2</sub> for the samples. Data sources are the same as <a href="#minerals-14-01220-f004" class="html-fig">Figure 4</a>.</p>
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<p>(<b>a</b>) Chondrite-normalized REE patterns and (<b>b</b>) primitive mantle-normalized element spidergrams. The values used for normalization are adopted from [<a href="#B59-minerals-14-01220" class="html-bibr">59</a>]. Data sources are the same as <a href="#minerals-14-01220-f004" class="html-fig">Figure 4</a>.</p>
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<p>Diagram of (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> versus ε<sub>Nd</sub>(t) values.</p>
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<p>Diagram of zircon <sup>206</sup>Pb/<sup>238</sup>U ages versus ε<sub>Hf</sub>(t) values of adakitic rocks, mafic intrusions/dykes and alkaline complex.</p>
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<p>Diagrams of (<b>a</b>) hornblende classification [<a href="#B64-minerals-14-01220" class="html-bibr">64</a>]; (<b>b</b>) hornblende equilibrium temperature versus equilibrium pressure; (<b>c</b>) plagioclase Or-Ab-An [<a href="#B65-minerals-14-01220" class="html-bibr">65</a>]; (<b>d</b>,<b>e</b>) variation in An and FeO values of plagioclase phenocrysts.</p>
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<p>Diagrams of (<b>a</b>) Ni versus MgO; (<b>b</b>) CaO/Al<sub>2</sub>O<sub>3</sub> versus MgO [<a href="#B27-minerals-14-01220" class="html-bibr">27</a>]. Data sources are the same as <a href="#minerals-14-01220-f004" class="html-fig">Figure 4</a>.</p>
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<p>Plots of (<b>a</b>) Sr/Y versus Y and (<b>b</b>) (La/Yb)<sub>N</sub> versus Yb<sub>N</sub> (after [<a href="#B68-minerals-14-01220" class="html-bibr">68</a>]). Data sources are the same as <a href="#minerals-14-01220-f004" class="html-fig">Figure 4</a>.</p>
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<p>Plots of (<b>a</b>) Mg# versus SiO<sub>2</sub> (after [<a href="#B80-minerals-14-01220" class="html-bibr">80</a>]), (<b>b</b>) Ni versus SiO<sub>2</sub>, and (<b>c</b>) Cr versus SiO<sub>2</sub> (after [<a href="#B81-minerals-14-01220" class="html-bibr">81</a>]). Data sources are the same as <a href="#minerals-14-01220-f004" class="html-fig">Figure 4</a>.</p>
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<p>Plots of (<b>a</b>) Ba versus Nb/Y, (<b>b</b>) Th/Yb versus Ba/La, (<b>c</b>) Ba/Y versus Nb/Y, (<b>d</b>) Th/Yb versus Sr/Nd (after [<a href="#B76-minerals-14-01220" class="html-bibr">76</a>]). Data sources are the same as <a href="#minerals-14-01220-f004" class="html-fig">Figure 4</a>.</p>
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<p>Schematic diagram of the evolution in the Early Cretaceous. Modified form [<a href="#B27-minerals-14-01220" class="html-bibr">27</a>].</p>
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14 pages, 22048 KiB  
Article
Geology and Zircon U-Pb Geochronology of the Las Cruces Intrusive Suite, B.C.S., México
by Ernesto Ramos-Velázquez, Raúl E. Lugo-Zazueta, Jobst Wurl, Miguel A. Imaz-Lamadrid and Tomás I. Grijalva Rodríguez
Geosciences 2024, 14(12), 322; https://doi.org/10.3390/geosciences14120322 - 28 Nov 2024
Viewed by 374
Abstract
The Las Cruces intrusive suite is located at the southern extent of the Baja California Peninsula in northwestern Mexico. The suite constitutes the northern part of the Los Cabos Batholitic Complex. It is correlated with extensive Cretaceous magmatic activity extending across California and [...] Read more.
The Las Cruces intrusive suite is located at the southern extent of the Baja California Peninsula in northwestern Mexico. The suite constitutes the northern part of the Los Cabos Batholitic Complex. It is correlated with extensive Cretaceous magmatic activity extending across California and the Baja Peninsula, known as the Peninsular Ranges Batholith. Despite its significance for understanding the regional tectonic and magmatic evolution, detailed information to fully support this correlation remains limited. This work provides new cartographic and structural data of the units comprising the intrusive suite and the temporal relationships between lithological units, supported by U-Pb zircon geochronology. The suite consists of granite in its central part, tonalite displaying magmatic foliation at its NW and SE margins, and two gabbro apophyses along the western edge. The host rocks consist of intercalations of hornblende and biotite schists, forming screens and roof pendants. Late magmatic felsic dikes, derived from the granite, intrude into the suite units. Five new U-Pb zircon age determinations indicate that the suite has a normal crystallization history with ages from 103.5 ± 1.2 to 97.6 ± 0.8 Ma for the tonalite and from 93.6 ± 0.7 to 95.0 ± 0.9 Ma for the granite. The gabbro is the oldest intrusive unit, with previous U-Pb zircon ages reported near 109 ± 2.3 and 102.3 ± 2.9 Ma. Structural analysis indicates that the gabbro and tonalite were emplaced during an E–W synmagmatic compressional event, evidenced by N–S oriented magmatic foliation, aligning subparallel to the granite and metasedimentary screens contacts. Later, the granite was emplaced during a compressional stress relaxation phase, causing the tonalite dissection and forming the current suite margins. The calculated U-Pb ages for the Las Cruces intrusive suite and reported geochemical and geophysical data from the northern Baja California Peninsula support its correlation with the Peninsular Ranges batholith. Full article
(This article belongs to the Section Structural Geology and Tectonics)
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<p>(<b>A</b>) Main tectonic features from NW México, related to the North American and Pacific plate boundaries. The main tectonic features from NW México are related to the boundaries of the North American and Pacific plates. SAF: San Andreas Fault, BC: Baja California state, BCS: Baja California Sur state. (<b>B</b>) Regional geology map of the southernmost tip of the Baja California peninsula, showing the main lithological units that compose the Los Cabos Batholitic Complex (LCBC), dissected by transpeninsular faults. The area considered in detail in the present work is shown as <a href="#geosciences-14-00322-f002" class="html-fig">Figure 2</a>.</p>
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<p>(<b>A</b>) Geological map of the Las Cruces Intrusive Suite (LCIS), mainly composed of granite and tonalite. (<b>B</b>) Geological cross-section (<b>a</b>,<b>a’</b>) shows gabbro outcrops on the western side, while cross-section (<b>b</b>,<b>b’</b>) shows metasedimentary screens that align with the tonalite magmatic foliation.</p>
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<p>(<b>A</b>) Poles to foliation in metasedimentary rocks. (<b>B</b>) Poles to magmatic foliation in the tonalite. The mean plane and pole for foliations are presented in red lines and squares, respectively in both datasets. This indicates a similar structural trend for metasediments and tonalite foliations from the LCIS.</p>
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<p>Outcrops of the Las Cruces intrusive suite units. (<b>A</b>) Intrusive contact between tonalite and granite, with cross-cutting late magmatic dikes; S<sub>1</sub>, foliation, H, hammer for scale. (<b>B</b>) Intrusive relationships between late magmatic dykes and magmatic foliation in tonalite; E, enclave. (<b>C</b>) Outcrop of the metasedimentary screen with sub-vertical foliation cross-cut by late magmatic dykes. (<b>D</b>) Intrusive contact between tonalite and metasedimentary, with parallel magmatic and metamorphic foliation.</p>
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<p>Petrographic textures of intrusive rocks from the studied area. (<b>A</b>) Magmatic foliation in tonalite, defined by preferential lineament of hornblende (Hb), biotite (Bi), and plagioclase (Pg) crystals; [<a href="#B28-geosciences-14-00322" class="html-bibr">28</a>]. (<b>B</b>) Non-foliated granite.</p>
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<p>Zircons U-Pb geochronology results for a sample of tonalite with magmatic foliation (ERV-13-01) from the western side of the LCIS. (<b>A</b>) Concordia age plot showing the analyzed zircon grains, (<b>B</b>) weighted mean age plot, and (<b>C</b>) Cathodoluminescence image of the representative individual zircon grains showing the laser-ablation spot location in pink circles.</p>
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<p>Zircons U-Pb geochronology results for the sample of tonalite with magmatic foliation (MSAL-02) from the eastern side of the LCIS. (<b>A</b>) Concordia age plot showing the analyzed zircon grains, (<b>B</b>) weighted mean age plot, and (<b>C</b>) Cathodoluminescence image of the representative individual zircon grains.</p>
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<p>Zircons U-Pb geochronology results for the diorite sample included as an enclave in tonalite with magmatic foliation (MSAL-01) from the eastern side of the LCIS. (<b>A</b>) Concordia age plot showing the analyzed zircon grains, (<b>B</b>) weighted mean age plot, and (<b>C</b>) Cathodoluminescence image of the representative individual zircon grains.</p>
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<p>Zircons U-Pb geochronology results for the granite (MSAL-03) granite (MSAL-03) sample from the western side of the LCIS. (<b>A</b>) Concordia age plot showing the analyzed zircon grains, (<b>B</b>) Weighted mean age plot, and (<b>C</b>) Cathodoluminescence image of the representative individual zircon grains.</p>
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<p>Zircons U-Pb geochronology results for the granite sample (ERV-13-01) from the western side of the LCIS. (<b>A</b>) Concordia age plot showing the analyzed zircon grains, (<b>B</b>) weighted mean age plot, and (<b>C</b>) Cathodoluminescence image of the representative individual zircon grains.</p>
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17 pages, 13556 KiB  
Article
Structural Characteristics of E–W-Trending Shear Belts in the Northeastern Dabie Orogen, China: Evidence for Exhumation of High–Ultrahigh-Pressure Rocks
by Yongsheng Wang, Xu Zhang and Qiao Bai
Minerals 2024, 14(12), 1205; https://doi.org/10.3390/min14121205 - 26 Nov 2024
Viewed by 389
Abstract
The Dabie–Sulu Orogen hosts the largest area of ultrahigh-pressure (UHP) rocks in the world. There is still significant divergence regarding the exhumation process and mechanism of UHP rocks in the Dabie Orogen, which mainly resulted from the erosion of large volumes of rocks [...] Read more.
The Dabie–Sulu Orogen hosts the largest area of ultrahigh-pressure (UHP) rocks in the world. There is still significant divergence regarding the exhumation process and mechanism of UHP rocks in the Dabie Orogen, which mainly resulted from the erosion of large volumes of rocks in the Orogen during the post-collisional stage. Based on detailed field investigations, this study discovered the occurrence of E–W-trending sinistral shear belts that developed on the northeastern Dabie Orogen. These shear belts formed under greenschist facies conditions and are characterized by steep foliation and gentle mineral lineation. E–W-trending shear belts developed in HP rocks with metamorphic ages ranging from 227 to 219 Ma and were cut by the older phase of ductile shear belts of the Tan-Lu Fault Zone, indicating that they were formed around 219–197 Ma. Based on a comprehensive analysis of existing data, it can be concluded that E–W-trending shear belts were formed during the exhumation process of HP–UHP rocks. When HP rocks returned to the shallow crust and the lower UHP rocks continued to move, stress concentration occurred in the HP rocks and further resulted in the formation of E–W-trending shear belts. The development of E–W-trending shear belts indicates that HP–UHP rocks had essentially returned to the shallow crust by the Late Triassic, marking the near completion of the exhumation process. Full article
(This article belongs to the Special Issue Geochemistry and Geochronology of High-Grade Metamorphic Rocks)
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<p>Geological sketch of the northeastern Dabie Orogen. (<b>a</b>) The location of the Central China Orogenic Belt. (<b>b</b>) A simplified tectonic framework of the Dabie Orogen (modified after Xu et al. [<a href="#B25-minerals-14-01205" class="html-bibr">25</a>]). (<b>c</b>) Detailed structural map of the Tongcheng massif. (<b>d</b>) Lower-hemisphere, equal-area stereograms of poles to the mylonitic foliation and plunges of mineral elongation lineation of the E–W-trending and NE–SW-trending shear belts in the northeastern Dabie Orogen. (<b>e</b>) Cross-sections showing tectonic framework of the Dabie Orogen (Section line in (<b>b</b>)). TLF: Tan-Lu Fault Zone; SMF: Shangcheng–Macheng Fault; XMSZ: Xiaotian–Mozitan shear zone; WSF: Wuhe–Shuihou Fault; HMF: Hualiangting–Mituo Fault; TMF: Taihu–Mamiao Fault; XSF: Xishui Fault; XGF: Xiangfan–Guangji Fault.</p>
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<p>Field photos of gneisses and mylonites in the northeastern Dabie Orogen. (<b>a</b>) Development of brittle NE–SW-trending faults in gneisses with flat-lying foliation; (<b>b</b>) steeply chlorite-bearing ultramylonite and (<b>c</b>) granitic mylonite; (<b>d</b>) S-C structures in marble mylonite indicates sinistral shear; (<b>e</b>,<b>f</b>) development of E–W-trending shear zone in gneisses with flat-lying foliation.</p>
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<p>Micrographs of mylonites from the E–W-trending shear belts in the northeastern Dabie Orogen. (<b>a</b>) Broken feldspar and recrystallized quartz; (<b>b</b>) fine-grain recrystallized quartz with a few larger quartz grains; (<b>c</b>) crossed polarizers and (<b>d</b>) single polarizers micrographs of ultramylonite, with banded chlorite, sericite and a few epidotes, with sinistral shear; (<b>e</b>) σ-type feldspar porphyroclasts in the ultramylonite indicating sinistral shear; (<b>f</b>) e-twin of calcite in the marble mylonite. Quartz within rectangular frame for EBSD testing. Qz: quartz; Fsp: feldspar; Pl: plagioclase; Ep: epidote.</p>
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<p>Quartz CPO pattern of mylonites from E–W-trending shear belts in the northeastern Dabie Orogen. Lower-hemisphere, equal-area projection. <span class="html-italic">n</span>: measured grain numbers. <span class="html-italic">X</span> and <span class="html-italic">Z</span> are principal axes of finite strain. Thin sections are parallel with <span class="html-italic">XZ</span> plane.</p>
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<p>Cathodoluminescence images of a selection of the dated zircons from mylonites in the eastern Dabie Orogen. Red circles indicate analytical sites.</p>
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<p>Concordia diagrams and weighted mean ages of zircons from mylonites in the E–W-trending shear belts in the northeastern Dabie Orogen.</p>
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<p>Schematic diagram of tectonic evolution during syn-collisional exhumation and post-collisional uplift. (<b>a</b>) During the Late Triassic to the Early Jurassic, the subducted SCB was exhumed to the shallow crust and resulted in the formation of a fold-and-thrust belt in the northern Yangtze Block and the Hefei foreland basin in the southern NCB. (<b>b</b>) Post-collisional uplift caused rocks overlying the ND unit to be eroded and rebuilt the tectonic framework of the Dabie Orogen. The diamond represents the outcrop location of HP–UHP rocks, and the numbers in parentheses are the ages when these HP–UHP rocks returned to the shallow crust. The dashed lines show the eroded part of units in the Dabie Orogen. Age data are from Liu et al. [<a href="#B10-minerals-14-01205" class="html-bibr">10</a>], Leech et al. [<a href="#B11-minerals-14-01205" class="html-bibr">11</a>], Ayers et al. [<a href="#B31-minerals-14-01205" class="html-bibr">31</a>], and the references therein. Please refer to the manuscript for abbreviated names.</p>
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<p>Schematic model of the formation of E–W-trending shear belts in the northeastern Dabie Orogen during the Late Triassic. To highlight the relationship between the formation of E–W-trending shear belts and the exhumation process of HP–UHP rocks, we neglected other units within the orogen in this figure. Please refer to the manuscript for abbreviated names.</p>
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16 pages, 11454 KiB  
Article
Discovery and Geological Significance of Neoproterozoic Bimodal Intrusive Rocks in the Dabie Orogen, China
by Linjing Li, Mingyi Hu, Lingyao Kong, Lin Wang and Qiqi Lyu
Minerals 2024, 14(12), 1199; https://doi.org/10.3390/min14121199 - 25 Nov 2024
Viewed by 372
Abstract
The Mingshan reservoir of the Dabie Orogen has a number of Neoproterozoic bimodal intrusive rocks. We focused on the zircon U-Pb chronology, Hf isotopes, and bulk-rock geochemistry of these rocks. The results showed the following: (1) The bimodal intrusive rocks mainly consist of [...] Read more.
The Mingshan reservoir of the Dabie Orogen has a number of Neoproterozoic bimodal intrusive rocks. We focused on the zircon U-Pb chronology, Hf isotopes, and bulk-rock geochemistry of these rocks. The results showed the following: (1) The bimodal intrusive rocks mainly consist of monzogranitic gneiss and plagioamphibolite, with zircon U-Pb ages of 785.0 ± 7.1 Ma and 787.3 ± 6.1 Ma, respectively. These ages indicate that they were formed in the late Qingbaikou epoch of the Neoproterozoic era. (2) The monzogranitic gneiss was dominated by peraluminous features and displayed a strong right deviation of REE (rare-earth element) patterns and a negative δEu anomaly. It is enriched in the LILEs (large-ion lithophile elements) Rb, Ba, and K, but slightly depleted in Nb, Sr, P, and Ti, with low 10,000* Ga/Al values, indicating that it is similar to Al-type granite. The plagioamphibolite belongs to the metaluminous, peraluminous series. It has a Mg# (molar ratio of Mg to Mg + Fe) of 36.1~55.9 and is enriched in the LILEs Rb, Ba, and K, with a slight positive anomaly of Ba, and is depleted in Nb and Sr. (3) The monzogranite shows negative zircon εHf(t) values ranging from −13.4 to −7.2 and a Paleoproterozoic TDM2(Hf) (two-stage depleted mantle model age) of 1969–2298 Ma. The zircon εHf(t) values and TDM2(Hf) of the plagioamphibolite were concentrated around 2.9–5.7 and 1257–1410 Ma, respectively. The geochemistry and Hf isotopes show that the monzogranitic gneiss and plagioamphibolite have distinct magmatic sources. The plagioamphibolite formed from mantle and partial continental crustal materials. The monzogranitic gneiss, on the other hand, was formed as a result of the partial melting of the shallow ancient felsic crust caused by mafic rock heating or upwelling. Taking into account regional correlation, the middle Neoproterozoic bimodal intrusive rocks originated in the structural framework of an extensional setting. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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Figure 1
<p>(<b>a</b>) Precambrian geological overview map of Qinling–Dabie Orogen; (<b>b</b>) geological map of the study area.</p>
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<p>Field (<b>a</b>–<b>c</b>,<b>e</b>) and micrographs (<b>d</b>,<b>f</b>) of bimodal intrusive rocks in Mingshan reservoir in the north of Dabie Orogen. (<b>a</b>) Interbedded monzogranitic gneiss (light color) and plagioamphibolite (dark color); (<b>b</b>) contact relationship between monzogranitic gneiss (light color) and plagioamphibolite (dark color); (<b>c</b>) field photographs of monzogranitic gneiss; (<b>d</b>) orthonormal polariscope photographs of monzogranitic gneiss; (<b>e</b>) field photographs of plagioamphibolite; (<b>f</b>) orthonormal polariscope photographs of plagioamphibolite; Hbl—hornblende; Qtz—quartz; Pl—plagioclase; Kf—potassium feldspar; Bi—biotite.</p>
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<p>Typical CL images, <sup>206</sup>Pb/<sup>238</sup>U ages, and ε<sub>Hf</sub>(t) values of zircon from samples ZJY-1-14 and ZJY-2-14 (white solid circle is for U-Pb dating, yellow dashed circle is for Lu-Hf isotope analysis).</p>
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<p>Zircon U-Pb concordia diagrams and mean age diagrams of Neoproterozoic bimodal intrusive rocks in Dabie Orogen.</p>
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<p>(<b>a</b>) A/NK-A/CNK geochemical discrimination diagram (after Maniar and Piccoli, 1989 [<a href="#B44-minerals-14-01199" class="html-bibr">44</a>]); (<b>b</b>) FeO<sup>t</sup>/(FeO<sup>t</sup> + MgO)-SiO<sub>2</sub> diagram (after Frost et al., 2001 [<a href="#B45-minerals-14-01199" class="html-bibr">45</a>]).</p>
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<p>(<b>a</b>) Nb/Y-SiO<sub>2</sub> diagram (after Winchester and Floyd, 1997 [<a href="#B46-minerals-14-01199" class="html-bibr">46</a>]) and (<b>b</b>) SiO<sub>2</sub>-FeO<sup>t</sup>/MgO diagram (after Miyashiro, 1975 [<a href="#B47-minerals-14-01199" class="html-bibr">47</a>]) for the bimodal intrusive rocks in Dabie Orogen.</p>
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<p>(<b>a</b>) Chondrite-normalized REE patterns and (<b>b</b>) N-MORB-normalized trace element patterns for the monzogranitic gneiss and plagioamphibolite in the Dabie Orogen. ((<b>a</b>) Normalizing values are from Boynton [<a href="#B48-minerals-14-01199" class="html-bibr">48</a>]; (<b>b</b>) normalizing values are from Sun and McDonough [<a href="#B49-minerals-14-01199" class="html-bibr">49</a>]).</p>
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<p>Zircon age—<span class="html-italic">ε</span><sub>Hf</sub>(<span class="html-italic">t</span>) (<b>a</b>), Nb-Nb/U (<b>b</b>), and Ce-Ce/Pb (<b>c</b>) diagrams for plagioamphibolite ((<b>b</b>,<b>c</b>) after Hofmann et al., 1986 [<a href="#B50-minerals-14-01199" class="html-bibr">50</a>]).</p>
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<p>(<b>a</b>) Y and (<b>b</b>) Ce vs. 10,000* Ga/Al; (c) Nb-Y-3Ga discrimination diagram of monzogranitic gneiss in the Dabie Orogen ((<b>a</b>,<b>b</b>) after Whalen et al., 1987 [<a href="#B53-minerals-14-01199" class="html-bibr">53</a>]; (<b>c</b>) after Eby G N., 1992 [<a href="#B54-minerals-14-01199" class="html-bibr">54</a>]). Abbreviations: A: A-type granites; I: I-type granites; S: S-type granites; M: M-type granites. A1 = granitoids in anorogenic settings; A2 = post-orogenic granites emplaced after a continental collision.</p>
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<p>Zr-Zr/Y, Zr-Ti, and Ta/Hf-Th/Hf diagrams for the bimodal intrusive rocks in Dabie Orogen of Neoproterozoic era ((<b>a</b>,<b>b</b>) after Pearce et al., 1973 [<a href="#B56-minerals-14-01199" class="html-bibr">56</a>]; (<b>c</b>) after Wang Y L, 2001 [<a href="#B57-minerals-14-01199" class="html-bibr">57</a>]). I: N-MORB in diverging plate boundary; II: converging plate boundary; III: intra-oceanic plate; IV: intra-continental plate; V: basalt region in mantle plume; WPB: within plate basalt, VAB: volcanic arc basalt, MORB: mid-ocean ridge basalt.</p>
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24 pages, 10810 KiB  
Article
Petrogenesis of the Shibaogou Mo-W-Associated Porphyritic Granite, West Henan, China: Constrains from Geochemistry, Zircon U-Pb Chronology, and Sr-Nd-Pb Isotopes
by Zhiwei Qiu, Zhenju Zhou, Nan Qi, Pocheng Huang, Junming Yao, Yantao Feng and Yanjing Chen
Minerals 2024, 14(11), 1173; https://doi.org/10.3390/min14111173 - 19 Nov 2024
Viewed by 510
Abstract
The Shibaogou pluton, located in the Luanchuan orefield of western Henan Province in China, is a typical porphyritic granite within the Yanshanian “Dabie-type” Mo metallogenic system. It is mainly composed of porphyritic monzogranite and porphyritic syenogranite. Zircon U-Pb dating results indicate emplacement ages [...] Read more.
The Shibaogou pluton, located in the Luanchuan orefield of western Henan Province in China, is a typical porphyritic granite within the Yanshanian “Dabie-type” Mo metallogenic system. It is mainly composed of porphyritic monzogranite and porphyritic syenogranite. Zircon U-Pb dating results indicate emplacement ages of 150.1 ± 1.3 Ma and 151.0 ± 1.1 Ma for the monzogranite and 148.1 ± 1.0 Ma and 148.5 ± 1.3 Ma for the syenogranite. The pluton is characterized by geochemical features of high silicon, metaluminous, and high-K calc-alkaline compositions, enriched in Rb, U, Th, and Pb, and exhibits high Sr/Y (18.53–58.82), high (La/Yb)N (9.01–35.51), and weak Eu anomalies. These features indicate a source region from a thickened lower crust with garnet and rutile as residual phases at depths of approximately 40–60 km. Sr-Nd-Pb isotopic analyses suggest that the magmatic source is mainly derived from the Taihua and Xiong’er Groups of the Huaxiong Block, mixed with juvenile crustal rocks from the Kuanping and Erlangping Groups of the North Qinling Accretion Belt. Combined with geological and isotopic characteristics, it is concluded that the Shibaogou pluton formed during the compression–extension transition period associated with the collision between the Yangtze Block and the North China Craton, reflecting the complex partial melting processes in the thickened lower crust. The present study reveals that the magmatic–hydrothermal activity at Shibaogou lasted approximately 5 Ma, showing multi-phase characteristics, further demonstrating the close relationship between the pluton and the Mo-W mineralization. Full article
(This article belongs to the Section Mineral Geochemistry and Geochronology)
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Figure 1
<p>(<b>a</b>) Tectonic subdivision map of China, showing the location of the Qinling Orogen (modified after [<a href="#B24-minerals-14-01173" class="html-bibr">24</a>]); (<b>b</b>) tectonic subdivision map of the Qinling Orogen, showing the location of the Luanchuan orefield (modified after [<a href="#B24-minerals-14-01173" class="html-bibr">24</a>]); (<b>c</b>) geological map of Luanchuan orefield, showing the granitoid and deposits distribution (modified after [<a href="#B25-minerals-14-01173" class="html-bibr">25</a>]).</p>
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<p>Geological map of Shibaogou deposit (modified after [<a href="#B34-minerals-14-01173" class="html-bibr">34</a>]). The number of drill holes: 1. ZK6002; 2. ZK6204; 3. ZK6402; 4. ZK6602.</p>
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<p>Geological profiles for prospecting lines L64 (<b>a</b>) and L03 (<b>b</b>) of the Shibaogou deposit [<a href="#B34-minerals-14-01173" class="html-bibr">34</a>].</p>
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<p>Photographs showing petrography of the Shibaogou granite. (<b>a</b>) Hand specimen of monzogranite; (<b>b</b>) monzogranite under plane-polarized light (PPL), with euhedral-tabular plagioclase phenocrysts and anhedral microcline and quartz; (<b>c</b>) monzogranite under crossed-nicols light (CN); (<b>d</b>) sericitized monzogranite (PPL), with chloritized biotite and sericitized–kaolinized orthoclase; (<b>e</b>) hand specimen of K-feldspar-altered monzogranite; (<b>f</b>) K-feldspar alteration in monzogranite (PPL), with plagioclase phenocrysts altered to orthoclase, while orthoclase phenocrysts remain unaltered; (<b>g</b>) hand specimen of syenogranite; (<b>h</b>) microphotograph of syenogranite (PPL), with anhedral quartz and orthoclase phenocrysts as the main components; (<b>i</b>) microphotograph of syenogranite (CN). Mineral abbreviations: Bi. biotite; Mc. microcline; Or. orthoclase; Pl. plagioclase; Qz. quartz; Ttn. titanite.</p>
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<p>Cathodoluminescence (CL) images of zircons from the Shibaogou granite. The red circles indicate the locations of U-Pb dating analyses.</p>
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<p>Zircon U-Pb Concordia diagram of samples from the Shibaogou granite. Monzogranite samples: (<b>a</b>) 6602-11, (<b>b</b>) 6204-60. Syenogranite samples: (<b>c</b>) 6402-36, (<b>d</b>) 6002-1.</p>
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<p>Major elements variation diagrams for the Shibaogou granite: (<b>a</b>) SiO<sub>2</sub> vs. K<sub>2</sub>O plots (base map after [<a href="#B47-minerals-14-01173" class="html-bibr">47</a>]); (<b>b</b>) A/NK vs. A/CNK discriminant diagram (base map after [<a href="#B47-minerals-14-01173" class="html-bibr">47</a>]).</p>
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<p>Chondrite-normalized REE patterns ((<b>a</b>,<b>c</b>), normalized values are from [<a href="#B49-minerals-14-01173" class="html-bibr">49</a>]) and primitive mantle-normalized trace element patterns ((<b>b</b>,<b>d</b>), normalized values are from [<a href="#B50-minerals-14-01173" class="html-bibr">50</a>]) for the Shibaogou granite.</p>
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<p>Whole-rock lead isotopic composition diagram of Shibaogou granite. (<b>a</b>) <sup>208</sup>Pb/<sup>204</sup>Pb vs. <sup>206</sup>Pb/<sup>204</sup>Pb diagram; (<b>b</b>) <sup>207</sup>Pb/<sup>204</sup>Pb vs. <sup>206</sup>Pb/<sup>204</sup>Pb diagram. The Pb isotope of strata has been recalculated to 150 Ma, and the initial data are from Taihua and Xiong’er Group [<a href="#B55-minerals-14-01173" class="html-bibr">55</a>,<a href="#B56-minerals-14-01173" class="html-bibr">56</a>,<a href="#B57-minerals-14-01173" class="html-bibr">57</a>,<a href="#B58-minerals-14-01173" class="html-bibr">58</a>], Luanchuan and Guandaokou Group [<a href="#B59-minerals-14-01173" class="html-bibr">59</a>], and Kuanping and Erlangping Group [<a href="#B60-minerals-14-01173" class="html-bibr">60</a>]. The trends for U (upper crust), O (orogenic belt), M (mantle), and L (lower crust) are from [<a href="#B54-minerals-14-01173" class="html-bibr">54</a>].</p>
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<p>Discriminant diagrams for tectonic environment of Shibaogou granite. (<b>a</b>) Granite (Y + Nb)-Rb tectonic diagram (base map from [<a href="#B63-minerals-14-01173" class="html-bibr">63</a>]). (<b>b</b>) Granite Hf-Rb/30-Ta × 3 tectonic diagram (base map from [<a href="#B64-minerals-14-01173" class="html-bibr">64</a>]).</p>
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<p>(<b>a</b>) La/Sm vs. La plot shows a batch partial melting trend [<a href="#B70-minerals-14-01173" class="html-bibr">70</a>]; (<b>b</b>) Ba vs. Sr plot shows the trend of mineral fractionation phase (arrow direction are after Rollinson [<a href="#B71-minerals-14-01173" class="html-bibr">71</a>]), ruling out the influence from the fractionation of plagioclase and hornblende. Bi = biotite, Hb = hornblende, Kf = K-feldspar, Ms = muscovite, Pl = plagioclase.</p>
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<p>The <span class="html-italic">I</span><sub>Sr</sub>-<span class="html-italic">ε</span><sub>Nd</sub>(<span class="html-italic">t</span>) diagram of Shibaogou granite (t = 150 Ma). The Sr-Nd isotope of strata has been recalculated to 150 Ma, and the initial data are from the Taihua Supergroup [<a href="#B57-minerals-14-01173" class="html-bibr">57</a>,<a href="#B86-minerals-14-01173" class="html-bibr">86</a>,<a href="#B87-minerals-14-01173" class="html-bibr">87</a>], Xiong’er Group [<a href="#B58-minerals-14-01173" class="html-bibr">58</a>,<a href="#B88-minerals-14-01173" class="html-bibr">88</a>,<a href="#B89-minerals-14-01173" class="html-bibr">89</a>], Qinling Group [<a href="#B90-minerals-14-01173" class="html-bibr">90</a>], Kuanping Group and Erlangping Group [<a href="#B60-minerals-14-01173" class="html-bibr">60</a>], Yudongzi Group, and Kongling Group [<a href="#B84-minerals-14-01173" class="html-bibr">84</a>,<a href="#B91-minerals-14-01173" class="html-bibr">91</a>].</p>
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<p>Zircon Hf isotopic diagram of Shibaogou granite (t = 150 Ma). Data on Shibaogou granite are from <a href="#app1-minerals-14-01173" class="html-app">Table S6</a>. Data of strata are from the Guandaokou Group [<a href="#B92-minerals-14-01173" class="html-bibr">92</a>], Kuanping and Erlangping Group (the crustal material of North Qinling) [<a href="#B92-minerals-14-01173" class="html-bibr">92</a>,<a href="#B93-minerals-14-01173" class="html-bibr">93</a>], Qinling Group [<a href="#B93-minerals-14-01173" class="html-bibr">93</a>], Xiong’er Group [<a href="#B89-minerals-14-01173" class="html-bibr">89</a>,<a href="#B94-minerals-14-01173" class="html-bibr">94</a>], and Taihua Supergroup [<a href="#B26-minerals-14-01173" class="html-bibr">26</a>,<a href="#B95-minerals-14-01173" class="html-bibr">95</a>,<a href="#B96-minerals-14-01173" class="html-bibr">96</a>,<a href="#B97-minerals-14-01173" class="html-bibr">97</a>].</p>
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<p>Yanshanian tectonic model of Qinling orogen and genesis model of the Shibaogou pluton (modified after [<a href="#B9-minerals-14-01173" class="html-bibr">9</a>]).</p>
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