Precambrian Research最新文献

{"title":"The formation of a unified basement of the Yangtze Craton","authors":"Liang Zhang ,&nbsp;Shao-Bing Zhang","doi":"10.1016/j.precamres.2025.107770","DOIUrl":"10.1016/j.precamres.2025.107770","url":null,"abstract":"<div><div>The Yangtze Craton has a long evolution history since the Eoarchean. With the increasing number of studies on the Yangtze Craton, ten Archean-Paleoproterozoic basements, separated from each other, have been identified. These basements may represent independent microcontinental blocks before they were amalgamated into a unified basement. To decipher their affinities with each other and when these microcontinental blocks joined together to form the basement of the Yangtze Craton, we compiled the Archean-Mesoproterozoic magmatic and metamorphic events and zircon U-Pb ages with Hf isotope data of magmatic rocks in these basements. Magmatic activities of basements in the Yangtze Craton mainly occurred within nine periods: approximately 3.7 Ga, 3.1–2.9 Ga, 2.9–2.7 Ga, 2.7–2.6 Ga, 2.5–2.4 Ga, 2.4–2.2 Ga, 2.1–1.9 Ga, 1.9–1.7 Ga, 1.7–1.6 Ga. By comparing the timings of tectono-thermal events and calculating the likeness of igneous zircon Hf isotopes between them, we reconstructed the assembly history of these microcontinental blocks and the formation time of the unified basement of the Yangtze Craton. The amalgamation history can be briefly summarized as: Yangkou was assembled with Dabie at ca. 3.7 Ga; Cuoke was merged with Phan Si Pan during 3.1–2.9 Ga to form the proto-south Yangtze Craton; Zhongxiang and Kongling were assembled during 2.9–2.8 Ga; Yangkou-Dabie, Zhongxiang-Kongling, and Yudongzi were assembled during 2.7–2.6 Ga; Feidong and Douling joined the Yangkou-Dabie-Zhongxiang-Kongling-Yudongzi assemblage during 2.5–2.4 Ga, constituting the proto-north Yangtze Craton. The coeval development of ca. 2.0 Ga metamorphism in the proto-south and the proto-north Yangtze Craton suggests that the amalgamation of the Yangtze Craton may have occurred as early as approximately 2.0 Ga. The occurrence of 1.9–1.7 Ga A-type granites and mafic dykes indicative of extension in both the northern and southwestern blocks marks the final assembly of the Yangtze Craton. The development of late Paleoproterozoic-Mesoproterozoic sedimentary strata with sporadic interlayered mafic volcanics in most parts of the Yangtze Craton suggests the stability of the Yangtze Craton. Based on the aforementioned evidence, we propose that a unified basement of the Yangtze Craton was formed no later than the late Paleoproterozoic, coeval with the final assembly of the supercontinent Columbia (Nuna).</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107770"},"PeriodicalIF":3.2,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768132","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":"Tectonic evolution of the crustal section of the Neoproterozoic Jabal Ess ophiolite-arc complex, Midyan terrane, NW Arabian Shield","authors":"Scott A. Whattam ,&nbsp;Faris Sulistyohariyanto ,&nbsp;Keewook Yi ,&nbsp;Mutasim Osman ,&nbsp;Oktarian Iskandar ,&nbsp;Jieun Seo","doi":"10.1016/j.precamres.2025.107765","DOIUrl":"10.1016/j.precamres.2025.107765","url":null,"abstract":"<div><div>The Jabal Ess ophiolite arc complex (JEOA) comprises basalt and basaltic andesite lavas and dykes and rare gabbros that range from MORB- and Izu Bonin Marianas forearc basalt (IBM FAB)-like to volcanic arc basalt-like but also comprise high-Mg andesite (HMA) and low-Si boninite (LSB); post-ophiolite formation granitoids intrude the ophiolite complex. Though the mafic rocks have major oxide compositional characteristics similar to MORB and IBM FAB, these mafic rocks exhibit prominent primitive mantle normalized negative Nb/Nb* anomalies and HFSE concentrations that range to much lower than MORB. We posit that the Jabal Ess ophiolite formed in adherence to the subduction initiation rule (i.e., MORB-like lavas followed by HMA and LSB) which is at least partially verified by the fact that LSB diabase are intrusive into lowermost peridotite. U-Pb SHRIMP ages of a lone rhyolite and two granites that intrude ophiolite mafic rocks are 687.6 ± 6.5 Ma and 699.0 ± 6.3 to 702.9 ± 6.2 Ma, respectively, and represent post-collisional granitoids that formed during collision of the Hijaz and Midyan terranes which aided in stitching of the 701–695 Ma Yanbu suture zone.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107765"},"PeriodicalIF":3.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738417","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":"Evidence for a Proterozoic carbonatite system in the Mount Isa Province, Australia","authors":"Alex Brown ,&nbsp;Carl Spandler ,&nbsp;Thomas G. Blenkinsop","doi":"10.1016/j.precamres.2025.107784","DOIUrl":"10.1016/j.precamres.2025.107784","url":null,"abstract":"<div><div>Carbonatites are indicators of mantle processes, and they are economically important because of their association with rare earth element (REE), niobium and base metal deposits. Carbonatites and their associated lithologies (i.e. the carbonatite system) have not previously been identified in eastern Australia. We describe veins of dolomite calcite carbonatite, fenites and antiskarn, glimmerite, and alkali pegmatite from the Tommy Creek Domain, of the Eastern Subprovince of the Mount Isa Province (NW Queensland), that constitute a carbonatite system. The system can be identified from field relationships, geochronology, zircon trace elements, and stable and radiogenic isotopes. The emplacement of the carbonatite system coincided temporarily and spatially with regional hydrothermal alteration at ca. 1650 Ma in the Eastern Subprovince, which also has mantle isotopic affinities and is located above the boundary between thin and thick continental lithosphere.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107784"},"PeriodicalIF":3.2,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143748326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New geochronological evidences and diverse arc-related meta-volcanic rock suits from the Northern Liaoning terrane, North China Craton","authors":"Rongrong Guo ,&nbsp;Yang Xiao ,&nbsp;Changming Wei ,&nbsp;Ming Yan ,&nbsp;Ningfeng Du","doi":"10.1016/j.precamres.2025.107755","DOIUrl":"10.1016/j.precamres.2025.107755","url":null,"abstract":"<div><div>The Northern Liaoning terrane locates at the northeastern margin of the North China Craton (NCC). Two debatable tectonic mechanisms, plate tectonic vs. plume/sagduction, were interpreted to dominate the late Neoarchean Northern Liaoning terrane. Besides, ∼2.57–2.51 Ga supracrustal rocks occur layered or as enclaves within ∼ 2.59–2.50 Ga TTG and potassium-rich granitoid gneisses. This is a logical contradiction that ‘young’ enclaves expose within ‘older’ wall rocks. In this study, new zircon U-Pb dating results exhibit that protoliths for these <em>meta</em>-volcanic rocks in the Huiyuan area, north of the Northern Liaoning terrane, crystallized at ∼ 2.61 Ga and underwent metamorphisms at ∼ 2.54–2.48 Ga. The real crystallization ages for reported metavolcanic rocks in the Northern Liaoning terrane were probably highly underestimated.</div><div>In this contribution, garnet–pyroxene amphibolite, amphibolite and (biotite) amphibole gneiss were interbedded and exhibit geochemical affinities to Nb-enriched basalt (NEB), tholeiite and andesite, respectively. NEB exhibits abnormally high Nb, TiO₂ and (Nb/La)_PM values, fractionated REE patterns, and negligible Nb, Ta and Ti anomalies, which was derived from partial melting of slab melts metasomatized mantle wedge with Nb-bearing minerals (i.e., amphibole). Tholeiites yield flat REE patterns, enrichments of LILEs, and depletions of Nb and Zr, which are comparable to primitive arc basalt and interpreted as partial melting of sub-arc mantle wedge previously metasomatized by limited subducted slab-derived fluids. Andesites give fractionated REE patterns and negative HFSE anomalies, among which several andesites are akin to Phanerozoic high-magnesium andesite (HMA), with high MgO, Mg^#, Cr and Ni values, and were generated by interactions between subducted slab-derived melts and sub-arc mantle wedge. Remained normal andesites were hybrids of crustal melts and mantle-derived basaltic melts. Taken together, ∼2.61 Ga NEB, andesite (including HMA samples) and primitive arc basalt associations point to a subduction tectonic mechanism developing in the Northern Liaoning terrane. Plume and subduction mechanisms are not mutually exclusive. More precise spatial and temporal distributions effected by plume and subduction, respectively, and how they interact with each other, need to be further studied.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107755"},"PeriodicalIF":3.2,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738415","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":"High-resolution chemostratigraphy reveals a large δ13C gradient in the ∼ 1.56 Ga redox-stratified ocean","authors":"Jin Luo ,&nbsp;Simon W. Poulton ,&nbsp;Bo Chen ,&nbsp;Lanyun Miao ,&nbsp;Kai Chen ,&nbsp;Haijing Sun ,&nbsp;Zhenfei Wang ,&nbsp;Guoxiang Li ,&nbsp;Maoyan Zhu","doi":"10.1016/j.precamres.2025.107785","DOIUrl":"10.1016/j.precamres.2025.107785","url":null,"abstract":"<div><div>Reports of decimeter-scale eukaryotic fossils and oxygenation events in the Gaoyuzhuang Formation (∼1.56 Ga, North China Craton) have provided valuable insight into potential links between life and the environment during the early Mesoproterozoic. However, the detailed nature of this relationship remains unclear, partly due to a limited basin-wide stratigraphic framework. Here, we present high-resolution carbon isotope compositions for carbonate and organic matter (δ¹³C_carb and δ¹³C_org) in two fossil-hosting sections, representing shallow and deeper water settings, to calibrate the timing of marine oxygenation and eukaryotic evolution, and to reveal coeval carbon cycle dynamics. Our high-resolution data display a dynamic δ¹³C_carb pattern with four perturbations in Gaoyuzhuang members III-IV, and suggest a causal link between oxygenation and eukaryotic evolution during the second perturbation. The δ¹³C_carb values exhibit a narrow range, but a distinct ∼ 2.5 ‰ isotopic gradient exists between shallow and deeper water during the third perturbation. By contrast, δ¹³C_org values reflect a more stable, but larger, isotopic gradient (∼7‰), implying decoupling of the carbon isotopic system. We propose that the δ¹³C_org compositions of shallow and deeper waters were controlled by specific microbial communities in a redox-stratified water column and a larger deep-ocean DOC reservoir, whereas δ¹³C_carb sensitivity was buffered by a large DIC reservoir. Our modeling also highlights that the coeval oxygenation events were able to drive the observed short-term δ¹³C_carb gradient during the third perturbation. Our findings reveal a direct relationship between environmental change and eukaryotic evolution, with implications for understanding Mesoproterozoic carbon cycle dynamics and paleo-redox conditions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107785"},"PeriodicalIF":3.2,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143724172","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 possible northward subduction in the southwestern Yangtze block during the Rodinia assembly: New constraints from three-dimensional magnetotelluric imaging","authors":"Shibin Xia ,&nbsp;Qiao Wang ,&nbsp;Jian Yang ,&nbsp;Xiaozhuang Cui ,&nbsp;Gang Min ,&nbsp;Gang Zhang ,&nbsp;Guozhong Liao ,&nbsp;Dewei Li ,&nbsp;Guangming Ren","doi":"10.1016/j.precamres.2025.107772","DOIUrl":"10.1016/j.precamres.2025.107772","url":null,"abstract":"<div><div>The Yangtze block is a crucial component of the Rodinia and Columbia supercontinents, providing insights into their evolutionary history. The newly identified Caiziyuan-Tongan accretionary complex (CAC), situated on the southwestern margin of the Yangtze block, serves as an ideal window for understanding its Precambrian evolution. The exposure of the CAC suggests the presence of an ancient ocean basin that divides the Yangtze block into northern and southern micro-blocks. During the convergence of the Rodinia supercontinent, this ocean basin underwent subduction and eventual closure; however, its associated subduction polarity remains ambiguous. To address this issue, this study employed magnetotelluric in the Caiziyuan-Tongan area. Through three-dimensional inversion, three distinct features were delineated: an upper crustal conductor in the southern CAC, a middle-upper crustal resistor trending stepwise north in the northern CAC, and a middle-lower crustal conductor encompassing the entire area. In conjunction with previously published geological and seismological observations, it is proposed that the first two features may be remnants associated with the northward subduction of the south Yangtze micro-block, while the third feature may indicate the existence of crustal flow related to the collision of the Indo-Asian plate. This finding enhances our understanding of the Precambrian evolution within the Yangtze block and contributes to the reconstruction of paleogeographic frameworks associated with the Rodinia supercontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107772"},"PeriodicalIF":3.2,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715206","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":"Paleoproterozoic continental crust accretion on the northern margin of the North China Craton: Evidence from the Shangyi Complex at the eastern segment of the Khondalite Belt","authors":"Yinchuan Wang ,&nbsp;Zuochen Li ,&nbsp;Xianzhi Pei ,&nbsp;Meng Wang ,&nbsp;Hai Zhou ,&nbsp;Ruiguang Wang ,&nbsp;Tong Zhang ,&nbsp;Hao Lin ,&nbsp;Irshad Hussain ,&nbsp;Xiao Wang ,&nbsp;Xue Jiang ,&nbsp;Song Gao ,&nbsp;Yongjie Yan","doi":"10.1016/j.precamres.2025.107774","DOIUrl":"10.1016/j.precamres.2025.107774","url":null,"abstract":"<div><div>The North China Craton (NCC) is considered a part of the Columbia Supercontinent, and geological records related to the convergence and breakup events of the Columbia Supercontinent have been preserved to varying degrees. The Shangyi Complex, located at the tectonic conjunction of the Khondalite Belt and the Trans-North China Orogen (TNCO) on the northern margin of the NCC, recorded the tectonic magmatic activities related to the collision orogeny of the Ordos Block and the Yinshan Block at ∼1950 Ma and the Western and Eastern Blocks at ∼1850 Ma respectively. The Shangyi Complex mainly comprises leucogranite, garnet granite, and gabbro. In this paper, LA-ICP-MS zircon U-Pb dating, whole rock geochemistry, and Lu-Hf isotope studies on leucogranite and garnet granite are conducted, and the ages of the zircons are 1961 ± 20 Ma and 1873 ± 20 Ma respectively. Geochemical characteristics show that they are all S-type granites. The results of the zircon Lu-Hf isotope show that the <em>ε</em>_Hf(t) values of the leucogranite zircons range from −5.86 to + 5.88, with an average value of +1.11, and the two-stage model ages (T_DM2) range from 2943 Ma to 2222 Ma, which is formed by the partial melting of ancient crusts during the collision of the Yinshan Block and the Ordos Block. The <em>ε</em>_Hf(t) values of the garnet granite zircon range from +0.86 to +2.53, with an average value of +1.50, and the two-stage model ages (T_DM2) range from 2464 Ma to 2361 Ma, which is formed by the partial melting of Paleoproterozoic crusts during the collision of the Western Block and the Eastern Block. The gabbro geochemical characteristics show that it possess alkaline rock property, which was formed by the underplating of mantle-derived magma in the post-collision extension stage after the collision of the Western and Eastern Blocks.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107774"},"PeriodicalIF":3.2,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706423","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":"Rodinia supercontinent assembly in the southeastern North China Craton: Detrital zircon evidence from the late Ediacaran Fengtai Formation","authors":"Mingzhen Tan ,&nbsp;Zhensheng Li ,&nbsp;Zhongwu Lan ,&nbsp;Wei An ,&nbsp;Ding Wang","doi":"10.1016/j.precamres.2025.107775","DOIUrl":"10.1016/j.precamres.2025.107775","url":null,"abstract":"<div><div>The position of the North China Craton (NCC) within Rodinia remains debated due to the notable absence of magmatic and orogenic records associated with the Rodinia assembly. Nevertheless, the discovery of abundant Grenvillian-aged detrital zircons from the late Ediacaran Fengtai Formation diamictites in the southeastern NCC provides a significant opportunity to evaluate the NCC’s affiliations with Rodinia. Detrital zircon U–Pb–Hf isotopic analyses reveal distinct age patterns of the Fengtai Formation in the Bagongshan and Sishilichangshan areas. The Fengtai Formation in the Bagongshan area is notable for its Mesoproterozoic–Neoproterozoic transition zircons, exhibiting a prominent age peak at approximately 0.99 Ga and subsidiary peaks at about 1.19 Ga, 1.43 Ga, 1.65 Ga, 1.92 Ga, and 2.50 Ga. Conversely, the diamictite in the Sishilichangshan area is marked by Neoarchean–Paleoproterozoic and secondary Mesoproterozoic zircons, featuring a primary age peak at about 2.04 Ga and minor peaks at approximately 0.90–1.00 Ga, 1.12–1.48 Ga, 1.87 Ga, 2.31 Ga, and 2.46 Ga. The Fengtai Formation sediments were derived from the late Mesoproterozoic–early Neoproterozoic cover and/or Archean–Paleoproterozoic basement in the southeastern NCC. The Neoarchean–Paleoproterozoic zircons are attributed to the basement rocks and/or the cover’s clastic rock units, whereas the Mesoproterozoic zircons represent recycled detritus from the cover’s clastic rock units. Furthermore, the Mesoproterozoic–Neoproterozoic transition zircons are interpreted as recycled tuffaceous components from the cover’s carbonate rock units. The elemental signatures of these transition zircons suggest that the associated felsic magmatic activity occurred in a continental arc orogenic setting. Notably, the declining trend of zircon <em>ε</em>_Hf<em>(t)</em> values from 1385 to 778 Ma is indicative of the presence of an interior orogenic system. These lines of evidence support the hypothesis of Grenvillian-aged orogenesis occurring in southeastern NCC, thereby affirming the NCC’s involvement in the Rodinia assembly, particularly the southeastern NCC–northwestern Laurentia connection, as demonstrated through paleomagnetic data and provenance analyses of the pre-Cryogenian cover.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107775"},"PeriodicalIF":3.2,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706422","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":"Zircon, monazite and titanite U-Pb geochronology revealing Orosirian metamorphic events within the Guiana Shield, Amazonian Craton","authors":"Matheus Scalabrin,&nbsp;Robert de Lima Muniz,&nbsp;Ticiano José Saraiva dos Santos","doi":"10.1016/j.precamres.2025.107766","DOIUrl":"10.1016/j.precamres.2025.107766","url":null,"abstract":"<div><div>Petrography coupled with U-Pb geochronology of migmatites enables the observation of processes and mechanisms involved in continental crust generation and transformation during orogeny. This study focuses on high-grade rocks of four lithostratigraphic units in the Guiana Shield, Amazonian Craton: the Trairão Suite, the Cauarane Group, the Rio Urubu Suite, and the Serra da Prata Suite. Petrographical and geochronological studies of these units reveal that the Orosirian Akawai Orogeny took place from approximately 2.04 to 1.93 Ga. During these 110 million years two high-grade events occurred associated with partial melting and magmatism. Metamorphic event M₁ (2.02 – 1.99 Ga), represented by a grey diatexite of the Trairão Suite, is related to fluid-present partial melting under amphibolite facies conditions. The age of anatexis (2.02 Ma) was obtained for zircon from a dioritic metatexite enclave in the diatexite. The crystallization of the melt generated in this event occurred at 2.00 Ga, obtained for zircon from the grey diatexite. Hornblende-biotite metatexite (Rio Urubu Suite), garnet-sillimanite-K-feldspar metatexite (Cauarane Group), and clinopyroxene-hornblende-orthopyroxene gneiss (Serra da Prata Suite) record the second high-grade metamorphic event M₂ (1.97 – 1.93 Ga). The anatexis of the Cauarane Group occurred by biotite dehydration under high amphibolite to granulite facies conditions. The crystallization of the anatectic melt in the Cauarane Group occurred between ca. 1.96 Ga (metamorphic zircon rims) and 1944 ± 5 Ma (U-Pb monazite). The water-fluxed partial melting in the hornblende-biotite metatexite (Rio Urubu Suite) took place under amphibolite facies conditions, with the crystallization of the anatectic melt occurring at 1938 ± 11 Ma. Granulite facies metamorphism occurred in lenses of clinopyroxene-hornblende-orthopyroxene gneiss of the Serra da Prata Suite at 1949 ± 4 Ma (metamorphic zircon) contemporaneous with dry magma emplacement. Statherian reactivation along NE-SW-trending shear zone in the center of the Guiana Shield was identified in titanite in hornblende-biotite metatexite (Rio Urubu Suite), probably induced by the accretion of the Rio Negro Belt (1.86 – 1.72 Ga).</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107766"},"PeriodicalIF":3.2,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143715277","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":"Tectonically-induced neptunian dykes and breccias of the Paleoproterozoic Teena Dolomite: Significance to stratiform zinc deposits in the McArthur Basin, Australia","authors":"Mana Ryuba ,&nbsp;Malcolm W. Wallace ,&nbsp;Ashleigh v.S. Hood ,&nbsp;Christopher P. Reed ,&nbsp;Nicola Cawood","doi":"10.1016/j.precamres.2025.107768","DOIUrl":"10.1016/j.precamres.2025.107768","url":null,"abstract":"<div><div>A widespread system of breccias and neptunian dykes is present within the Paleoproterozoic Teena Dolomite of the McArthur Basin. Most breccia types within the unit are infilled by early fibrous marine cements and dark grey sediments. We interpret the dominant breccia types as <em>in-situ</em> synsedimentary fracture systems (neptunian dykes) while some matrix-supported breccias are likely to be mass flow deposits. Fibrous marine cements filling the neptunian dykes have several different textures and all now consist of dolomite. Petrographic evidence indicates the cements were likely precipitated as calcite and dolomitized during early diagenesis. The trace and rare earth element chemistry of the marine cements is typical of Paleoproterozoic marine cements and indicate relatively anoxic marine conditions.</div><div>The breccias in the Teena Dolomite appear to be the result of a basin-wide tectonic event that occurred during Teena Dolomite to early Barney Creek time at ∼1640 Ma. Early marine-cemented neptunian dykes likely formed by tectonic fracturing and gravitational collapse on tectonic highs. Many large stratiform Zn-Pb deposits in northern Australia (HYC, Teena, Lady Loretta, Mt Isa) are hosted by shales that are coeval with this tectonic event, suggesting a genetic link between tectonism and mineralization. We suggest that this ∼1640 Ma tectonic event is responsible for both the release of mineralization fluids (via faulting and/or dewatering), and the deposition of deeper water organic-rich fine-grained sediments that host the mineralization (via tectonic subsidence). This tectonic event appears to be an important component of the sedimentary exhalative mineral system in the Carpentaria Zinc Belt of northern Australia.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107768"},"PeriodicalIF":3.2,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143697846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}