Precambrian Research最新文献

{"title":"Delineation of polymetamorphism from the middle-low-grade metamorphic complex in the Dengfeng area, southern North China Craton, resolved by multiple mineral petrochronology and phase equilibrium modelling","authors":"Qiang Feng ,&nbsp;Jun-Sheng Lu ,&nbsp;Xu Kong ,&nbsp;Gang Liu ,&nbsp;Yu-Ting Li ,&nbsp;Yi-Yi Zhang ,&nbsp;Zeng-Yin Duan ,&nbsp;Juan-Juan Li","doi":"10.1016/j.precamres.2025.107802","DOIUrl":"10.1016/j.precamres.2025.107802","url":null,"abstract":"<div><div>Polymetamorphic garnet–bearing amphibolites from the Dengfeng Complex (Central Henan, China) exhibit intricate microstructural and mineral-chemical relationships. Two generations of garnet porphyroblastand various mineral age populations have been identified in this middle-low-grade metamorphic complex. Garnet1, which co-exists with titanite in the ‘dark domain’, exhibits a trend of decreasing Mn, constant Mg and notably increasing Ca from its cores to rims, indicating growth zoning associated with prograde metamorphism from ∼590 °C–650 °C and ∼3.8–4.5 kbar to ∼650 °C–680 °C and ∼5.0–5.6 kbar by phase equilibrium modelling. By contrast, garnet2 from the ‘light domain’ displays a decrease in Ca alongside an increase in Mg and low Mn, reflecting clockwise pressure–temperature (P–T) paths with peak P–T conditions reached at ∼630 °C–645 °C and ∼10.9–11.6 kbar. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb and amphibole ⁴⁰Ar/³⁹Ar dating yielded polymetamorphic events with extensive Neoarchean records of ∼2.49–2.53 Ga and sporadic Palaeoproterozoic records of ∼1.94–1.86 Ga, respectively. By contrast, LA–(HR)–ICP–MS titanite U–Pb data from the ‘dark domain’ only recorded late Neoarchean metamorphic ages ranging from ∼2.44 to ∼2.54 Ga. The early metamorphism from the ‘dark domain’ is characterised by low pressure and high temperature, indicating a high T/P gradient towards ∼1200 °C–1300 °C/Gpa at the Neoarchean. By contrast, the late metamorphism from the ‘light domain’ underwent clockwise metamorphic cycles at an intermediate T/P gradient of ∼540 °C–590 °C/Gpa during the Palaeoproterozoic. The diachronous evolution of these amphibolites indicates that the Dengfeng Complex in the southern North China Craton has undergone low-pressure facies series metamorphism during the late Neoarchean, which was subsequently incorporated into supercontinent Columbia during the late Palaeoproterozoic cold subduction and continent–continent collision along the Trans-North China Orogen.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107802"},"PeriodicalIF":3.2,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892132","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 Ediacaran margin of the proterozoic MARA block and the sedimentary basins of the Clymene Ocean: Insights from U-Pb zircon geochronology in the Puna-Sierras Pampeanas transition, NW Argentina","authors":"C.D. Ramacciotti ,&nbsp;M.A. Larrovere ,&nbsp;C. Casquet ,&nbsp;C.I.Lembo Wuest ,&nbsp;M.Morales Cámera ,&nbsp;P.H. Alasino ,&nbsp;J.A. Murra ,&nbsp;A. Riveros ,&nbsp;M.A.S. Basei ,&nbsp;L. Herazo ,&nbsp;E.G. Baldo","doi":"10.1016/j.precamres.2025.107792","DOIUrl":"10.1016/j.precamres.2025.107792","url":null,"abstract":"<div><div>The basement of the sierras of Fiambalá and Altohuasi, in the Puna-Sierras Pampeanas transition (NW Argentina), consists mainly of early Cambrian metamorphic rocks (Fiambalá Metasedimentary Complex; new name) and granitoids (Loconte Intrusive Complex; new name). The metasedimentary complex consists of: 1) the Tatón Unit (gneisses, metatexites, diatexites and mylonites); and 2) the Laguna Helada Unit (low- to medium-grade fine-grained metaconglomerates with subordinated metapsammites, slates, phyllites, schists, mylonites and marbles). U-Pb zircon geochronology performed in the two units yields similar results suggesting that they were sourced from the same basements and probably belong to a continuous stratigraphic pile prior to metamorphism and ductile shearing. These units show a main group of ages between ca. 0.95 and 1.10 Ga, and a secondary group at ca. 1.15–1.25 Ga, with a minor peak at ca. 1.33 Ga, and few Paleoproterozoic-Neoarchean ages. This, along with zircon metamorphic overgrowths of 526 ± 4 Ma found in the Tatón Unit, and regional correlations, indicate that sedimentation took place in Ediacaran to early Cambrian times, in a mixed carbonate-siliciclastic platform bordering the extinct Clymene Ocean. Comparisons (lithology, Sr-isotopes and detrital zircon data) with similar successions recognized elsewhere in the Sierras Pampeanas, southern Puna, Cordillera Frontal, and Cordillera Oriental suggest that the sediments came from the same source areas and that they were part of a common sedimentary environment, i.e., the Difunta Correa Basin. The main source areas were the Grenville and the Granite-Rhyolite provinces of Laurentia and the MARA block. This basin – now dismembered by Paleozoic deformation – is one of the many basins formed along the margins of the Clymene Ocean lying in NW Argentina, southern Brazil, Paraguay, and Río de la Plata craton. The closure of this ocean, during the early Cambrian Pampean orogeny resulted in the low- to high-grade metamorphism of the Fiambalá Metasedimentary Complex.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107792"},"PeriodicalIF":3.2,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143879071","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":"Late Tonian subduction to collisional tectonics in the southwestern Tarim Craton: Arc volcanism and sedimentary archives of terminal Rodinia amalgamation","authors":"Duwei Qiu ,&nbsp;Fengqi Zhang ,&nbsp;Hongxiang Wu ,&nbsp;Yildirim Dilek ,&nbsp;Caiyun Wang ,&nbsp;Hanlin Chen ,&nbsp;Kongyang Zhu","doi":"10.1016/j.precamres.2025.107795","DOIUrl":"10.1016/j.precamres.2025.107795","url":null,"abstract":"<div><div>The southwestern margin of the Tarim Craton preserves significant geological records related to the assembly and fragmentation of the Rodinia Supercontinent. However, its Neoproterozoic tectonic evolution remains debated, complicating the reconstruction of the Tarim Craton within the Rodinia framework. This study presents a multidisciplinary approach integrating stratigraphic, geochronological, geochemical, and provenance analyses of Tonian successions and tuffaceous interlayers to constrain the timing and mechanisms of contractional events in the southwestern Tarim Craton. The Tonian Silu Group shows a regressive succession from shallow marine to fluvial-deltaic environments, capped by a regional unconformity beneath Cryogenian-Ediacaran strata. Tuffaceous interlayers suggest volcanic eruptions occurred between 802 Ma and 789 Ma, providing age constraints for the Sukuluoke Formation at the top of the Silu Group. These calc-alkaline tuffs exhibit arc-related geochemical signatures, suggesting continental arc magmatism along the southwestern margin of the Tarim Craton. Detrital zircon provenance and sedimentary facies analyses reveal that proximal Tonian magmatic arc clasts contributed significantly to the basins, possibly sharing a common source with the volcanic tuff. These findings, along with regional magmatism, stratigraphic unconformities, and coeval metamorphism, collectively suggest a mid-Neoproterozoic assembly event involving subduction and collision. A plausible tectonic scenario involving subduction, collision, and subsequent rifting is proposed for the Neoproterozoic evolution of the southwestern Tarim Craton. This model serves as a preliminary framework that will require further geological constraints to refine the regional geological history.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107795"},"PeriodicalIF":3.2,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143882287","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 Pingshan low-angle shear zone and its implications for the late Paleoproterozoic extension of the Trans-North China Orogen","authors":"Wangbin Gong ,&nbsp;Duwei Qiu ,&nbsp;Yuanfang Zhao ,&nbsp;Jianmin Hu ,&nbsp;Xia Liang","doi":"10.1016/j.precamres.2025.107797","DOIUrl":"10.1016/j.precamres.2025.107797","url":null,"abstract":"<div><div>The Trans-North China Orogen (TNCO) records the amalgamation of the Eastern and Western blocks to form the North China Craton (NCC) at ∼1.85 Ga. A series of geologic events related to regional extension occurred in the TNCO, represented by the ∼1.80–1.60 Ga Taihang-Lüliang mafic dyke swarms, the Yanliao rift, and the Xiong’er rift. However, the tectonic process and initial time of the extension remain unclear. The Pingshan ductile shear zone (PSSZ), located in the central part of the TNCO, has been interpreted as a Paleoproterozoic normal fault. In this study, we present the results of detailed field observations, and analyses of the microstructure, quartz c-axis fabrics, and geochronology of the PSSZ. The results show that the PSSZ underwent low-angle top-to-the-SE shearing at ∼1.84–1.83 Ga, with deformation temperatures ranging from 400 ℃ to 500 ℃. The nearly synchronous PSSZ and low-angle deformation zone developed on the northwestern margin of the Fuping Complex constitute an extensional structural system. These structures resulted in the rapid uplift of the Fuping Complex. The extensional structures in the central part, combined with the scattered anorogenic granite plutons developed along the orogen from north to south, indicated that the TNCO was dominated by post-orogenic extension during ∼1.84–1.80 Ga.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107797"},"PeriodicalIF":3.2,"publicationDate":"2025-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876516","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":"Neoproterozoic metasedimentary rocks in the eastern Songnen Massif, NE China: Implications for the early evolution and tectonic affinity of microcontinental massifs in the eastern Central Asian Orogenic belt","authors":"Yi-Ting Xue ,&nbsp;Jie Tang ,&nbsp;Wen-Li Hao ,&nbsp;Jin-Peng Luan ,&nbsp;Xin-Yu Long ,&nbsp;Shuang Liang ,&nbsp;Ji-Shuang Ding ,&nbsp;Wen-Liang Xu","doi":"10.1016/j.precamres.2025.107791","DOIUrl":"10.1016/j.precamres.2025.107791","url":null,"abstract":"<div><div>The early tectonic evolution and affinity of microcontinental massifs in the eastern Central Asian Orogenic Belt are uncertain. Here, we present LA–ICP–MS zircon U–Pb and <em>in situ</em> mica Rb–Sr ages, zircon Hf isotopic compositions, and geochemical data for metasedimentary rocks in the eastern Songnen Massif in NE China to constrain their depositional ages and sedimentary provenance, and decipher the early tectonic evolution and affinity of the Songnen Massif. The detrital zircon U–Pb ages yield seven main Neoproterozoic age populations, at ca. 730, ca. 760, ca. 795, ca. 830, ca. 855, ca. 890, and ca. 930 Ma, with six Paleo–Mesoproterozoic and Archean populations at ca. 1020, 1520–1220, 1750–1600, 2050–1950, 2500–2300, and ca. 2800 Ma. Combining this with the ages of later intrusive rocks and overlying sedimentary rocks, we conclude that the Xinxing and Hongguang formations of the Zhangguangcailing Group and the Liangzihe and Honglin formations of the Dongfengshan Group in the study area were deposited during the Neoproterozoic. The <em>in situ</em> mica Rb–Sr ages of the Neoproterozoic metasedimentary rocks suggest that metamorphism occurred during the Middle–Late Jurassic in the eastern Songnen Massif, possibly related to closure of the Mudanjiang Ocean between the Songnen and Jiamusi massifs. Geochemical data for these Neoproterozoic metasedimentary rocks suggest that they were sourced mainly from felsic igneous rocks located close to the sedimentary basin. Furthermore, the consistency between Neoproterozoic detrital zircon age populations and the episodes of magmatism documented in the eastern Songnen Massif suggests that the Neoproterozoic detritus was sourced from the Songnen Massif itself. The occurrence of Paleoproterozoic–Mesoproterozoic detrital zircon grains, together with two-stage Hf model (T_DM2) ages (2.2–1.0 Ga) of zircon grains from Neoproterozoic granitoids, indicates that Paleoproterozoic–Mesoproterozoic crustal material existed in the Songnen Massif. The metasedimentary rocks of the Zhangguangcailing and Dongfengshan groups have similar geochemical compositions and detrital zircon age populations, suggesting that they were formed in a continental arc setting. In addition, the Neoproterozoic–early Paleozoic detrital zircon age peaks, metamorphism, and sedimentary environment of Neoproterozoic strata suggest that the Songnen Massif was part of the North Indo-Australie Orogen and located close to the Tarim Craton during the Neoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107791"},"PeriodicalIF":3.2,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143858994","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":"Synthesis of structure and tectonic evolution of Meso-Neoproterozoic Vindhyan Basin, India using geophysical and geological data: A plate tectonic perspective","authors":"V. Vijaya Rao ,&nbsp;K. Laxminarayana ,&nbsp;Biswajit Mandal ,&nbsp;P. Karuppannan ,&nbsp;Prakash Kumar","doi":"10.1016/j.precamres.2025.107787","DOIUrl":"10.1016/j.precamres.2025.107787","url":null,"abstract":"<div><div>The Origin of the Mesoproterozoic intracratonic basins is not well understood compared with the Phanerozoic basins of the world. The present investigation attempts to comprehend the evolution of one such basin of Indian origin and relates its tectonic events with the amalgamation and fragmentation of supercontinents. The Vindhyan basin, India, is one of the largest Meso-Neoproterozoic basins in the world and has probable hydrocarbon potential. It is mostly undeformed and unmetamorphosed, except at the margins. Seismic reflection and refraction, gravity, and well data are integrated with geology, geochemistry, and geochronological data to understand the tectonic evolution of the region. A basement ridge identified in the study divides the basin into two parts: the Chambal valley in NW and Son-valley in SE, which contain 5.8 km and 4.5 km thick Proterozoic sediments. A collisional suture and an arc signature are identified at the Narmada-Son Lineament zone. We suggest a dual-stage foreland basin system has evolved due to the subduction of the leading edge of the Bundelkhand Craton beneath the Mewar and Bastar Cratons around 1.8 Ga. Subsequent collisions of these cratons resulted in the evolution of Aravalli and Satpura orogens. Nature of basin boundary faults, crustal-scale Great Boundary Thrust in NW, and the Narmada-Son lineament in SE, formed during the collision processes are discussed. Far-field plate boundary forces developed due to subduction-collision processes likely influenced the evolution of the basins subsequent to foreland setup. Presence of the Vindhyan Sea and tilting of the continental block to northeast during 1200–800 Ma resulted in common Upper Vindhyan sedimentation in the Chambal- and Son-Valley Basin, including the Ganga Basin in NE. Present study suggests extension of the Vindhyan Basin beneath the Ganga basin. We propose an evolutionary model in a plate tectonic framework that explains several aspects of the basin, including the formation of basin-central ridge during Proterozoic subduction process. The 2.5 Ga and 2.2 Ga events of the region are cotemporaneous with the assembly and breakup of Neoarchean supercontinent Kenorland. Timings of Lower and Upper Vindhyan sedimentation and termination broadly coincide with the assembly and breakup of Paleo- and Mesoproterozoic supercontinents Columbia and Rodinia.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107787"},"PeriodicalIF":3.2,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835397","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 significance of Archean sanukitoids in the cratonization process: The example of the Barlow pluton, between the Abitibi and Opatica subprovinces, Superior Craton, Quebec","authors":"Esther M.-A. Bou ,&nbsp;Dominique Genna ,&nbsp;Michel Jébrak ,&nbsp;Lucie Mathieu ,&nbsp;Jeffrey H. Marsh","doi":"10.1016/j.precamres.2025.107789","DOIUrl":"10.1016/j.precamres.2025.107789","url":null,"abstract":"<div><div>Much debate surrounds Archean crustal growth and its evolution, as well as processes leading to the stabilization of the crust (cratonization). The Barlow pluton is a late-tectonic granitoid that intrudes into the boundary between the Abitibi greenstone belt and the Opatica plutonic belt (Québec, Canada), two subprovinces that make up the southeastern part of the Superior Craton. The Barlow pluton and the Maaskitkuu tonalite, one of its host rocks, are useful to improve the understanding of tectonic and magmatic processes along the margins of subprovinces in Archean cratons. Here, whole-rock analyses, dating (U-Pb on zircon) and barometry on amphibole are used to define the petrogenesis of these two plutons. The older Maaskitkuu tonalite (ca. 2705 <!--> <!-->Ma) belongs to a Tonalite-Trondhjemite-Granodiorite (TTG) intrusive suite and has a high Sr/Y ratio. The Barlow pluton (ca. 2696 <!--> <!-->Ma) belongs to the sanukitoid group. The Maaskitkuu tonalite emplaced 10 km deeper than the Barlow pluton, pointing to the exhumation of 10 km of rocks in about 11 Ma, corresponding to an exhumation rate of 1.37 mm/yr. When combined with previous structural and seismic studies, the observations support an imbrication of terranes farther to the north and the south to explain the arrangement of both subprovinces, marked by a transcrustal structure. This structure allows melts from the lower crust and the metasomatized mantle to ascend toward the upper crust promoting the cratonization.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107789"},"PeriodicalIF":3.2,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143816317","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":"Detrital zircon record of shutdown and migration of Cadomian volcanic arcs in the Bohemian Massif, with implications for Ediacaran to early Cambrian plate kinematics","authors":"Jiří Žák ,&nbsp;Martin Svojtka ,&nbsp;R. Damian Nance ,&nbsp;J. Brendan Murphy","doi":"10.1016/j.precamres.2025.107786","DOIUrl":"10.1016/j.precamres.2025.107786","url":null,"abstract":"<div><div>This paper presents new U–Pb detrital zircon ages that constrain the age of deposition of a Cadomian intra-arc succession (Štěchovice Group in the Bohemian Massif) overlying one of the best preserved volcanic arcs (Davle volcanic complex) of the Avalonian–Cadomian belt, which rimmed the northern margin of Gondwana in the Neoproterozoic to Cambrian. The record of this active margin is well preserved, but how subduction terminated along it remains a matter of debate. Our new data from the Štěchovice Group suggest abrupt arc termination in this region followed by turbidite deposition in a short-lived basin at around 570 Ma. However, the ages of voluminous arc-derived graywackes in a neighbouring accretionary wedge suggest arc magmatism continued until ca. 527 Ma. Regional gravity highs inboard of the Davle volcanic arc indicate the presence of unexposed dense rocks that may represent the missing, post-570 Ma Cadomian arc. If so, the arc axis migrated landward, consistent with the presence of intrusive boninites within the older Davle arc, which would have then occupied a fore-arc position and must have been eroded and submerged prior to the deposition of Štěchovice Group. We suggest that the inferred arc migration beginning at around 570 Ma occurred in response to slab flattening due to the arrival of hotter oceanic lithosphere, perhaps in the form of a spreading ridge that migrated eastwards along the Avalonian–Cadomian active margin leaving a dextral transform margin in its wake. Such a ridge is thought to have first impinged on Avalonia to the west at around 600 Ma and later caused arc extinction in the Armorican Massif and Saxothuringian unit at around 570 Ma, with arc migration in the Bohemian Massif at about the same time. The ridge–trench interaction is then inferred for the Bohemian Massif in the early to middle Cambrian (at ca. 527–515 Ma), consistent with ongoing subduction in the more easterly proto-Alps until the mid-Ordovician. How the inferred migration of the ridge–trench–transform system was linked to the movement of Baltica, and whether it could have brought Baltica close enough to supply Mesoproterozoic detritus to Gondwana’s northern periphery remain open questions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107786"},"PeriodicalIF":3.2,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143807252","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":"Geochronology of the Vindhyan Supergroup: Implications for the closure of the Proterozoic basins of India","authors":"Bivin G. George ,&nbsp;Jyotiranjan S. Ray ,&nbsp;Milan K. Mahala ,&nbsp;J. Amal Dev ,&nbsp;J.K. Tomson ,&nbsp;J. Haripriya ,&nbsp;Alok Kumar","doi":"10.1016/j.precamres.2025.107790","DOIUrl":"10.1016/j.precamres.2025.107790","url":null,"abstract":"<div><div>The sediments of the Vindhyan Supergroup, deposited in the largest Proterozoic basin of India, are known to have recorded changes in the seawater chemistry, changes in global climate, and one of the earliest fossil records of multicellular eukaryotes. These rocks, particularly the upper part of the sequence, are also home to some of the most controversial fossils of the Neoproterozoic lifeforms. Despite receiving enough attention, the evolutionary timeline of the upper part of the supergroup and the timing of the closure of the Vindhyan Basin remained uncertain. Issues related to the stratigraphic correlation within the basin, temporal relation with other Proterozoic basins of India, and validity of the evidence of global events reported from the basin remained unresolved. Here, we present results of Pb-Pb dating of carbonate formations and detrital zircon U-Pb dating of sandstone formations of the upper Vindhyans from the western and the eastern sectors of the basin to resolve some of the above chronological issues. Based on Pb-Pb isochron ages, we establish that the Bhander Limestone formation in the Son Valley sector (eastern) was deposited in two major periods: one at 874 ± 77 (2σ) Ma and the other at 768 ± 36 (2σ) Ma, with breaks in sedimentation in between. Based on the Pb-Pb isochron age of 871 ± 78 (2 σ) Ma, the Balwan Limestone, the topmost carbonate formation in the Rajasthan sector (western), is proposed to be laterally correlatable to the Bhander Limestone in the Son Valley. The Lakheri Limestone formation in Rajasthan is deemed to have no correlatable carbonate formation in the Son Valley. The maximum depositional ages of sandstone formations, determined from zircon U-Pb data, suggest that the top part of the Vindhyan Supergroup is younger than 830 Ma. Our results establish that the closure of the Vindhyan Basin happened sometime during the late Tonian. Therefore, these successions are unlikely to contain evidence of the Cryogenian glaciations or the Ediacaran life. This new age information puts the Vindhyan Basin in the league of at least two other Proterozoic basins of India (i.e., Marwar and Kaladgi), which, contrary to general belief, had remained active during the Neoproterozoic (&lt; 1000 Ma). We did not find any evidence of coevolution of the Vindhyan Basin with other Proterozoic basins of India.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107790"},"PeriodicalIF":3.2,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143799907","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 U-Pb age and petrogenetic constraints on granitic magmatism from the southwestern Chhotanagpur Granite Gneiss Complex: Implications for Proterozoic crustal growth in the Central India","authors":"Mohammad Qasim ,&nbsp;Satya Narayana Mahapatro ,&nbsp;Sameer Ranjan ,&nbsp;Ajay Dev Asokan ,&nbsp;D. Srinivasa Sarma ,&nbsp;M. Ram Mohan","doi":"10.1016/j.precamres.2025.107783","DOIUrl":"10.1016/j.precamres.2025.107783","url":null,"abstract":"<div><div>The Chhotanagpur Granite Gneiss Complex (CGGC) is an integral part of the Central Indian Tectonic Zone (CITZ), which records the Proterozoic tectono-thermal evolution of the Indian Shield. In this study, we carried out detailed petrography, bulk rock geochemistry, Nd isotopic studies and U-Pb zircon geochronology for granitoids from the southwestern CGGC. Four episodes of granitic magmatism from this area are documented, which are (i) c. 1660 Ma granite gneiss, (ii) c. 1565 Ma foliated granite, (iii) c. 1462 Ma porphyritic granite, and (iv) c. 1140 Ma equigranular granite. The c. 1660 Ma granite gneisses are migmatitic, I-type, and their Nd isotopic compositions are mildly sub-chondritic (εNd_(t) = –0.90 to –2.55). The geochemical characteristics suggest them sourced from mafic to intermediate sources with inputs from pre-existing crustal rocks. The c. 1565 Ma foliated granites are peraluminous, S-type, and have evolved Nd isotopic composition (εNd_(t) = –2.40 to –4.69) with Mesoarchean model ages, which suggests their derivation from a metasedimentary source. The c. 1462 Ma porphyritic granite and c. 1140 Ma equigranular granites have geochemical attributes similar to the A₂-type granites. The strongly evolved Nd isotopic signatures (εNd_(t) = –4.39 to –5.38 and –6.81 to –8.38) for porphyritic granite and equigranular granite, respectively, suggest inputs from both enriched mantle and pre-existing crustal sources. Based on these findings, the Proterozoic evolution of the CGGC can be broadly divided into four stages, with stages 1 and 2 corresponding to c. 1660–1565 Ma arc magmatism, where the granite gneisses were emplaced, followed by the emplacement of foliated granites in the waning stage. Stage 3 corresponds to the emplacement of c. 1462 Ma A-type granites associated with the extensional environment. Stage 4 is associated with post-collisional setting where the c. 1140 Ma equigranular granites were formed. The presence of recrystallized zircon domains with c. 900–1000 Ma in all granitoid variants supports widespread Grenvillian high-grade metamorphism in the CITZ. These results suggest that granitoids from the southwestern CGGC exhibit a transitional tectonic regime with an initial arc followed by extensional tectonics, culminating in a post-collisional environment, possibly linked with the breakup of Columbia and the amalgamation of Rodinia supercontinents.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"422 ","pages":"Article 107783"},"PeriodicalIF":3.2,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768662","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}