Precambrian Research最新文献

{"title":"SIMS U-Pb dating of baddeleyite-zircon pairs in mafic rocks to determine the ages of magmatic mineralization and hydrothermal remobilization in a Ni-Cu-(PGE) deposit","authors":"Li-Xing Li ,&nbsp;Jian-Wei Zi ,&nbsp;Yu Liu ,&nbsp;Guo-Qiang Tang ,&nbsp;Hou-Min Li ,&nbsp;Yong Zhang ,&nbsp;Min-Xin You","doi":"10.1016/j.precamres.2024.107556","DOIUrl":"10.1016/j.precamres.2024.107556","url":null,"abstract":"<div><p>Ni-Cu-(PGE) sulfide deposits associated with mafic–ultramafic rocks are the most important sources of Ni and platinum-group elements (PGE) in the world. These deposits also contain significant amounts of Cu. Such deposits are generally considered to have formed by multiple stages of primary magmatic concentration and secondary hydrothermal remobilization. However, constraining the ages of Ni-Cu-(PGE) sulfide deposits has proven challenging, particularly those that have experienced post-magmatic hydrothermal overprinting and remobilization. The lack of robust geochronology data has hindered understanding of the geological controls on this important type of mineralization. The Chibaisong Ni-Cu-(PGE) sulfide deposit in the North China Craton is characterized by disseminated and net-textured ores formed by magmatic processes and overprinted by hydrothermal Cu-rich vein stockwork. The Cu-rich vein stockwork is fracture-controlled, and contains a mineral assemblage of Ni-Cu sulfides (chalcopyrite, pyrrhotite, pentlandite), amphibole and quartz. Chalcopyrite in the hydrothermal stockwork is relatively depleted in Ni but enriched in Ag and Cd compared with disseminated magmatic chalcopyrite, typical of hydrothermal superimposed ores as documented elsewhere. We identified baddeleyite-zircon pairs associated with Ni-Cu sulfides in hydrothermal superimposed ores of the Chibaisong deposit, in which the baddeleyite is unequivocally of primary igneous origin whereas the zircon represents the replacement product of baddeleyite during hydrothermal alteration. <em>In situ</em> SIMS U-Pb dating of baddeleyite and zircon yielded weighted mean ²⁰⁷Pb/²⁰⁶Pb ages of 2181 ± 21 Ma and 1892 ± 33 Ma, respectively, interpreted as the timing of magmatic mineralization and subsequent hydrothermal remobilization of the Ni-Cu-(PGE) deposit. Our results explain the large discrepancies in sulfide Re-Os ages previously obtained from this deposit. This study demonstrates that on the basis of detailed BSE imaging, <em>in situ</em> SIMS U-Pb dating of baddeleyite-zircon pairs can provide robust age constraints for both magmatic mineralization and hydrothermal remobilization of Ni-Cu-(PGE) sulfide deposits hosted in mafic–ultramafic intrusions, although further studies are needed to test whether the formation of such deposits commonly entails multiple stages of hydrothermal remobilization. Since baddeleyite or baddeleyite-zircon pairs are common accessory minerals in Ni-Cu-(PGE)-bearing mafic–ultramafic rocks, the dating approach employed in this study may be applicable to similar deposits elsewhere.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comment on “Subsurface distribution of granites and greenstones in the paleoarchean east Pilbara terrane from 3-D gravity inversion”","authors":"Arthur H. Hickman,&nbsp;Emeritus","doi":"10.1016/j.precamres.2024.107539","DOIUrl":"10.1016/j.precamres.2024.107539","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A subduction-dismembered Neoproterozoic large igneous province in the Qinling Orogenic Belt, China: Implications for 850 Ma–initiated mantle plume activity in the greater Yangtze Block","authors":"Di Feng ,&nbsp;Lu Xiong ,&nbsp;Chao Wang ,&nbsp;Mark B. Allen ,&nbsp;Jie Dong ,&nbsp;Chunjing Wei ,&nbsp;Li Su ,&nbsp;Shuguang Song","doi":"10.1016/j.precamres.2024.107553","DOIUrl":"10.1016/j.precamres.2024.107553","url":null,"abstract":"<div><p>Large igneous provinces (LIP) provide invaluable clues for recognizing the growth, breakup, and cycles of supercontinents and constraining the activity of ancient mantle plumes (or superplumes). The widespread intraplate magmatism is considered as a possible fingerprint of ancient plume activities and LIPs. Here, we present the results of an integrated study on protoliths of eclogites and amphibolite-facies bimodal volcanic rocks from North Qinling Ultrahigh-pressure Metamorphic (UHPM) Terrane, Qinling Orogen, and identify a dismembered Neoproterozoic LIP. These rocks share similar protolith ages of ca. 850–800 Ma and experienced high- to ultrahigh-pressure metamorphism at ca. 500–480 Ma. The mafic rocks are mainly tholeiitic and display enrichment of LILEs and HFSEs, similar to the E-MORB/OIB characters. They also have typical features of continental flood basalts (CFBs) with low CaO/Al₂O₃ (0.68–0.87), Lu/Yb (0.14–0.15), Zr/Nb (8–13), high Nb/La (0.87–1.24, mean 1.07), La/Nb (0.80–1.15), La/Ta (11–20), Nb/Yb (3.0–6.2) ratios, and positive ε_Nd(t) (+4.3 to + 5.4). Their occurrence, geochemical features, age data, and high mantle potential temperature (1500–1550 °C) suggest that they are remnants of Neoproterozoic CFBs with mantle plume origin. Based on the lateral distribution length (ca. 300 km) of <em>meta</em>-basaltic rocks and the maximum subduction depths (ca. 100–200 km) recorded by UHP eclogites, the identified ca. 850 Ma-initiated CFBs in the North Qinling terrane should represent an LIP, covering more than 100,000 km². This Neoproterozoic LIP, together with the coeval volcanic sequences in the South Qinling terrane and the northern Yangtze, would have occupied a maximum landmass of 300,000 km², which lends support for the onset of a mantle plume at ca. 850 Ma within the Rodinia supercontinent. We conclude that the Qinling Block is one of the fragments of the Rodinia supercontinent with a passive margin covered by CFBs, which was subducted to mantle depths in the Early Paleozoic.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142048816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reply to comments on “Subsurface distribution of granites and greenstones in the Paleoarchean East Pilbara Terrane from 3-D gravity inversion” of Hayward et al. (2024)","authors":"Nathan Hayward ,&nbsp;Andrew J. Calvert ,&nbsp;Huaiyu Yuan ,&nbsp;Klaus Gessner ,&nbsp;Michael P. Doublier","doi":"10.1016/j.precamres.2024.107554","DOIUrl":"10.1016/j.precamres.2024.107554","url":null,"abstract":"","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142048817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-episode mineralization in the Haerdaban Pb–Zn deposit, NW China: Insights from sulfide trace elements, in situ S–Pb isotopes, and Rb–Sr geochronology","authors":"Shunda Li ,&nbsp;Wenjiao Xiao ,&nbsp;Chuan Chen ,&nbsp;Miao Sang ,&nbsp;Qigui Mao ,&nbsp;Lingling Gao ,&nbsp;Fang Xia ,&nbsp;Xiang Li ,&nbsp;Xiaofei Du","doi":"10.1016/j.precamres.2024.107550","DOIUrl":"10.1016/j.precamres.2024.107550","url":null,"abstract":"<div><p>The Haerdaban Pb–Zn deposit, located in the eastern West Tianshan Orogen, hosts stratiform and vein-type mineralization within Precambrian carbonate rocks. However, there has been limited research on the distinctions and relationships between these two mineralization styles. In this study, we compared trace element distributions, fluid conditions, material sources, and mineralization ages between stratiform and vein-type mineralization and reconstructed a detailed genetic model. Two episodes and four stages of mineralization were identified, including five generations of pyrite and two generations of sphalerite. The sedimentary exhalative episode represents stratiform mineralization including Stage I pyrite–pyrrhotite layers (Py-1, Py-2a, Py-2b, and Py-3) and Stage II sphalerite–galena layers (Sph-1). The magmatic–hydrothermal episode represents vein-type mineralization including Stage III pyrite–quartz–calcite veins (Py-4) and Stage IV sphalerite–galena–quartz–calcite veins (Sph-2). LA–ICP–MS analysis of Se–Co–Ni–As–Ag–Sb–Bi contents in pyrite suggests that Py-1 to Py-3 formed under relatively low temperatures (280 ± 8 °C) and high ƒO₂ sedimentary conditions. Py-4 formed under relatively high temperatures (339 ± 18 °C) and low ƒO₂ hydrothermal conditions. Variations in Fe–Mn–In–Ga–Ge–Cd–Cu contents in sphalerite indicate that Sph-1 formed under relatively low temperature (211 ± 7 °C), intermediate ƒS₂ (logƒS₂ = −11.1 ± 0.5), and moderate pH sedimentary exhalative conditions. Sph-2 formed under relatively high temperature (292 ± 5 °C), high ƒS₂ (logƒS₂ = −7.4 ± 0.2), and low pH hydrothermal conditions. <em>In situ</em> analysis of sulfide S–Pb suggests that ore-forming materials for stratiform mineralization were primarily derived from marine sediments, while those for vein-type mineralization primarily originated from magmatic sources. Sph-1 from stratiform mineralization yielded an Rb–Sr isochron age of 719 ± 16 Ma, while Sph-2 from vein-type mineralization exhibited an Rb–Sr isochron age of 380.3 ± 7.7 Ma. Random Forest classification of trace elements in pyrite and sphalerite predicted that stratiform mineralization is of sedimentary genesis, whereas vein-type mineralization is of magmatic–hydrothermal genesis. Based on our results, we identified a two-episode mineralization history for the Haerdaban Pb–Zn deposit: Neoproterozoic syngenetic sedimentary exhalative mineralization overprinted by Devonian epigenetic magmatic–hydrothermal mineralization. The results of this study highlight the importance of considering multiple geological events in ore-forming processes and will facilitate the exploration of similar deposits in the West Tianshan Orogen.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Suturing of the Archean Bastar craton with the Eastern Ghats Province to form the Greater Indian Landmass: Insights from geochemistry, U-Pb geochronology and phase equilibria modelling","authors":"J. Padmaja ,&nbsp;Tapabrato Sarkar ,&nbsp;Somnath Dasgupta","doi":"10.1016/j.precamres.2024.107536","DOIUrl":"10.1016/j.precamres.2024.107536","url":null,"abstract":"<div><p>The contact between the Archean Bastar craton (BC) and Proterozoic Eastern Ghats Province (EGP), central India, is marked by a suture zone termed Terrane Boundary Shear Zone (TBSZ). BC in this area is largely composed of hornblende-biotite granite with some mafic dykes. Rocks in the TBSZ include quartzofeldspathic (leptynite) gneiss, garnet-orthopyroxene-bearing granitoid, mafic granulites (Group A of cratonic affinity, and Group B of EGP affinity), Mg-Al granulite and an isolated exposure of orthopyroxene-bearing gneiss. Detailed geochemical analysis shows remarkable similarity between Hbl-Bt granite and Grt-Opx-bearing granitoid, with A-type affinity, and between mafic dykes and Group A mafic granulites. However, the Opx-bearing gneiss is geochemically distinct having I-type affinity, similar to TTG gneisses described from BC. Metamorphic phase equilibria analysis and trace element modelling shows that (i) melting of Opx-bearing gneiss would produce a ferroan granitic melt resembling the Hbl-Bt granite, (ii) metamorphism at appropriate P-T conditions would convert the granite to Grt-Opx-bearing granitoid and the mafic dyke to Group A mafic granulite. U-Pb geochronology of zircon constrains emplacement ages of the magmatic precursors of Opx-bearing gneiss and Grt-Opx-bearing granitoid as ca. 2.73 and ca. 2.5 Ga, respectively. These rocks were subjected to an early granulite facies metamorphism, followed by an amphibolite facies metamorphism, shearing and hydrous fluid flux. Geochronological data shows that the latter event took place at ca. 0.52 Ga, while the earlier granulite facies event can only be tentatively suggested to be of late Stenian/Tonian age. Collating all the evidence (including published geophysical and geochronological data), we suggest that the initial collision between BC and EGP took place during late Stenian/Tonian time as a consequence of formation of the Greater Indian Landmass, a part of Rodinia supercontinent. The TBSZ, probably initiated due to the late Stenian/Tonian collision, was reactivated and reworked tectonothermally at ca. 0.52 Ga, caused by far field stress effect of the Kuunga orogeny, which was strong enough to obliterate most of the imprints of the late Stenian/Tonian orogeny.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142012549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polymetamorphic evolution of the Vestfold Block in East Antarctica and implications for the amalgamation of terranes","authors":"Zhao Liu ,&nbsp;Laixi Tong ,&nbsp;Omar Bartoli ,&nbsp;Bruna Borges Carvalho ,&nbsp;Chao Li ,&nbsp;Xinyue Han ,&nbsp;Kexin Wu","doi":"10.1016/j.precamres.2024.107549","DOIUrl":"10.1016/j.precamres.2024.107549","url":null,"abstract":"<div><p>The Vestfold Block, a typical polymetamorphic Archean terrane in East Antarctica, is a key area to understand amalgamations of Rodinia and East Gondwana continents. However, multiphase overprinting makes it difficult to determine the timing and nature of each tectonothermal event. In this study, we present P–T estimates, zircon, monazite U(–Th)–Pb and biotite/K–feldspar Rb–Sr isochron ages of paragneisses from the SE Vestfold Block. One paragneiss sample, which is assigned to the Chelnok Paragneiss, has experienced a protracted metamorphism from the Neoarchean to the early Paleoproterozoic. Phase equilibria modeling constrained the peak P–T conditions to 7.2–9.6 kbar and 850–880 ℃, and the post–peak metamorphism to 4.2–5.6 kbar and 720–790 ℃, respectively. On the other hand, a paragneiss sample close to the ice sheet documented a high–grade metamorphic event at 918 ± 23 Ma, with peak P–T conditions of 6.0–8.0 kbar and 860–880 ℃. Biotite/K–feldspar Rb–Sr dating for these two samples yields isochron ages of 474 ± 12 and 442 ± 7 Ma, respectively, representing the cooling ages of the Pan–African reworking. Collectively, an integrated application of diverse chronometers, combined with published data, indicates that the Vestfold Block may have experienced at least three major thermal events with variable intensities and extents. Initially, the supracrustal rocks in this region pervasively underwent a protracted high–grade thermal event from the Neoarchean to the early Paleoproterozoic, which formed the backbone of the block. Thereafter, the southern Vestfold Block experienced a Grenvillian granulite facies metamorphism, indicating that the Vestfold Block has been locally involved in the Rayner orogeny (i.e. the late Mesoproterozoic/early Neoproterozoic collision between the Indian craton and East Antarctica). Ultimately, the whole Vestfold Block may have been reworked under relatively low temperatures during the Pan–African Prydz tectonic event.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142006685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Union Tin Member of the Rooiberg Group: Geodynamic implications for the Bushveld Large Igneous Province, South Africa","authors":"Teimoor Nazari-Dehkordi ,&nbsp;Axel Hofmann ,&nbsp;Laurence Robb ,&nbsp;Eva E. Stüeken","doi":"10.1016/j.precamres.2024.107538","DOIUrl":"10.1016/j.precamres.2024.107538","url":null,"abstract":"<div><p>The Union Tin Member, comprising a succession of pyroclastic and shale-dominated sedimentary rocks associated with the 2.05 billion-year-old Bushveld Large Igneous Province (LIP), is well-exposed particularly in the Union Sn field located 150 km north of Pretoria, South Africa. The Union Tin Member is a laterally extensive (&gt;200 km-wide) marker horizon situated between the rhyolitic Kwaggasnek and Schrikkloof formations of the Rooiberg Group. The shale unit exhibits low total organic carbon (TOC) contents (168 ± 70 ppm) along with a narrow range of δ¹³C values (−27.7 ± 1.7 ‰) and δ¹⁵N values mostly around 0 ‰, resembling characteristics typical of marine shales. These siliciclastic sedimentary rocks were deposited in a shallow-marine sedimentary environment subjected to sea-level fluctuations, suggesting widespread submergence of the Kaapvaal Craton despite ongoing LIP magmatism. The whole-rock compositions, particularly rare earth elements (REE), Th, Sc, Zr, Ni, V and TiO₂, indicate a provenance dominated by the underlying Rooiberg Group, which may also include the Paleoproterozoic Transvaal Supergroup, Archean tonalite-trondhjemite-granodiorite (TTG) suites and greenstones. Variable enrichments of the shale in Sn, Li, Cs, W and U are primarily associated with chlorite, sericite, illite and hematite. Notably, the rhyolites, immediately underlying and overlying the Union Tin Member, are similarly altered to a mineral assemblage dominated by the Fe-Al-Mg-bearing phases with relative enrichments especially in Sn. Alteration is linked to large-scale Sn-bearing hydrothermal fluids derived from the Lebowa Granite Suite. The periodic emplacement of extensive volcanic rocks of the Rooiberg Group is likely to have resulted in a downsagged &gt;200 km-wide basin underlain by the Transvaal Supergroup. The deposition of the Union Tin Member within this basin could potentially represent the surface expression of a deep-seated, exceptionally large magma reservoir suggested to have contributed to the formation of the entire Bushveld LIP.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141998136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cambrian mercury mineralization event in South China: Insights from U-Pb dating of hydrothermal dolomite in the large Chatian Hg district","authors":"Fanyan Zhou ,&nbsp;Dengfei Duan ,&nbsp;Yan Liu ,&nbsp;Junqin Wang ,&nbsp;Haobo Jia ,&nbsp;Mathias Burisch ,&nbsp;Yi Zheng ,&nbsp;Yue Wu","doi":"10.1016/j.precamres.2024.107542","DOIUrl":"10.1016/j.precamres.2024.107542","url":null,"abstract":"<div><p>The genesis of many giant mercury (Hg) deposits/belts is widely debated largely because of a lack of reliable ore-forming age constraints. The LA-ICP-MS/MS dolomite U-Pb were employed to date the large Chatian Hg district in Xiangxi-Qiandong Hg belt of South China. The mineralization of this district can be divided into three stages: an initial Pyrite-Quartz stage before mercury deposition, a main Cinnabar-Sphalerite-Dolomite (<strong><em>Dol I</em></strong>) stage, and a subsequent Dolomite vein (<strong><em>Dol II</em></strong>) stage after ore formation. Three <strong><em>Dol I</em></strong> samples from the Chashula and Touponao Hg deposits were chosen for U-Pb dating, yielding ages of 509.8 ± 7.4 Ma, 509.4 ± 4.7 Ma and 507.4 ± 4.0 Ma respectively, indicating the mineralization occurred in the Cambrian Miaolingian, concurrent with or shortly after the deposition of the host-rock. These ages correspond with the emplacement periods of two Large Igneous Provinces (LIP) (the Pinghe silicic SLIP and the Kalkarindji LIP) in northeastern Gondwana, as well as the mantle-derived rocks in the study region. Combined with previous mercury isotopic data, our study proposes that the large-scale Hg mineralization in the area most likely resulted from the mantle-derived fluids, which would have directly contributed a significant amount of Hg for ore formation. Furthermore, the close timeframe between the Cambrian Series 2-Miaolingian trilobite extinction events and Hg mineralization in South China, may suggests a potential direct connection between the widespread mercury release and mineralization and the Cambrian Series 2-Miaolingian trilobite crisis in the region.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141991244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Major-trace element and Sr–Nd isotopic geochemistry of Paleoproterozoic gneisses from the Taihua Complex within the Xiaoqinling terrane: Insights into the evolution of the southern margin of the Trans-North China Orogen","authors":"Nancy Hui-Chun Chen ,&nbsp;Yunpeng Dong ,&nbsp;Bo Hui","doi":"10.1016/j.precamres.2024.107535","DOIUrl":"10.1016/j.precamres.2024.107535","url":null,"abstract":"<div><p>Although the early Paleoproterozoic global magmatism appears to be rare, the Taihua Complex within the Xiaoqinling terrane of the southern Trans-North China Orogen (TNCO) contains abundant evidence for magmatic and tectonic activities during this period. In this contribution, we present whole-rock geochemical and Sr-Nd isotopic data for the gneisses from the Taihua Complex within the Xiaoqinling terrane to investigate their petrogenetic processes, geodynamic setting, and provide a better understanding of the tectonic evolution in the southern margin of the TNCO. Based on their patterns of geochemical characteristics, the studied samples can be broadly subdivided into three groups. The Group-1 and −3 gneisses have relatively low Sr/Y ratios, and negative Eu anomalies, indicating plagioclase was a residual phase during partial melting, which requires relatively low pressure conditions. The majority of the samples in these groups have negative whole-rock εNd(t) values, indicating the magma source was mainly ancient crust. However, these Group-2 gneisses have moderate to high Sr/Y ratios, and high Mg#, which may related to mantle-melt interactions. This study shows that the protoliths of studied gneisses from the Taihua Complex within the Xiaoqinling terrane were probably formed by either partial melting of pre-existing arc lower crust or partial melting of the delaminated thickened lower crust and then interacted with the mantle components in a post-collisional extension tectonic regime, which is consistent with the global tectonic regime at this time.</p></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141984768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}