The late Archean granulite was found as tectonic slices amalgamated with the late Paleoproterozoic metamorphic rocks in the Pingquan area within the Paleoproterozoic Trans-North China Orogen. The late Archean intermediate granulite rocks with distinctive ‘red-eye socket’ texture record anticlockwise P-T paths and were metamorphosed at ∼2.5 Ga, whereas the late Paleoproterozoic mafic granulite and amphibolite with “white-eye socket” texture record clockwise P-T paths and were metamorphosed at 1.86–1.80 Ga. The 40Ar/39Ar ages (1.81–1.79 Ga) of hornblende further constrain the synchronous exhumation of these disparate metamorphic units, providing critical constraints on the Paleoproterozoic uplifting and cooling process. The juxtaposition of late Archean continental fragments with Paleoproterozoic subduction-related lithologies within a confined orogenic zone highlights the capacity of orogenic systems to preserve both juvenile accreted terranes and reworked more ancient continental fragments, implying remarkable longevity of continental materials through accretionary cycles. This phenomenon suggests that without detailed metamorphic-petrochronological analyses, amalgamated tectonic slices formed at different ages may remain unresolved, potentially leading to erroneous interpretations.
{"title":"Identification of survived Archean continental fragments in the Paleoproterozoic Trans-North China Orogen","authors":"Hui C.G. Zhang , Guochun Zhao , Wanfeng Zhang , Guo-Dong Wang , Chun-Ming Wu","doi":"10.1016/j.precamres.2025.107932","DOIUrl":"10.1016/j.precamres.2025.107932","url":null,"abstract":"<div><div>The late Archean granulite was found as tectonic slices amalgamated with the late Paleoproterozoic metamorphic rocks in the Pingquan area within the Paleoproterozoic Trans-North China Orogen. The late Archean intermediate granulite rocks with distinctive ‘red-eye socket’ texture record anticlockwise <em>P-T</em> paths and were metamorphosed at ∼2.5 Ga, whereas the late Paleoproterozoic mafic granulite and amphibolite with “white-eye socket” texture record clockwise <em>P-T</em> paths and were metamorphosed at 1.86–1.80 Ga. The <sup>40</sup>Ar/<sup>39</sup>Ar ages (1.81–1.79 Ga) of hornblende further constrain the synchronous exhumation of these disparate metamorphic units, providing critical constraints on the Paleoproterozoic uplifting and cooling process. The juxtaposition of late Archean continental fragments with Paleoproterozoic subduction-related lithologies within a confined orogenic zone highlights the capacity of orogenic systems to preserve both juvenile accreted terranes and reworked more ancient continental fragments, implying remarkable longevity of continental materials through accretionary cycles. This phenomenon suggests that without detailed metamorphic-petrochronological analyses, amalgamated tectonic slices formed at different ages may remain unresolved, potentially leading to erroneous interpretations.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107932"},"PeriodicalIF":3.2,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221691","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}
Pub Date : 2025-09-29DOI: 10.1016/j.precamres.2025.107934
Yuan Zhou , Xuelian You , Qing Li , Zhuofeng Zhang , Qiang Du , Zhengyu Wei , Xinlong Li , Hui Zhou
Microbial dolomites are extensively developed in the upper Ediacaran Dengying Formation (ca 551.1 to 542.0 Ma) in the Sichuan Basin, China. However, these microbial dolomites underwent complex depositional processes, and their sedimentary environments remain debated. In this study, the petrographic, mineralogical, and geochemical characteristics of microbial dolomites in the upper Ediacaran Dengying Formation are systematically analyzed. The microbial dolomites (stromatolites, thrombolites, oncoids, botryoidal dolomites) in the upper Ediacaran Dengying Formation demonstrate the interplay between microbial activity and environmental conditions in a shallow restricted platform. Microbial structural diversity reflects hydrodynamic-microbial synergy: stromatolites and botryoidal dolomites are formed in low-energy, high-activity settings; dispersed thrombolites are formed under weak microbial influence; layered/reticular thrombolites and oncoids are developed via particle aggregation in high-energy environments. Two transgressive–regressive cycles correlate with “dolomite sea” events: the first driven by global climate (evaporation, localized anoxia), the second by tectonic uplift (Tongwan Movement I), underscoring tectonics’ role in reservoir genesis. Geochemical indicators reflect post-glacial seawater stratification and weathering shifts, constraining environmental triggers for Ediacaran-Cambrian biotic complexity. Global comparisons reveal widespread microbial diagenesis during the Ediacaran, yet the Sichuan Basin exhibits unique tectono-climatic cyclicity. Although diagenesis obscures some geochemical signals, systematic analysis confirms the Dengying Formation as a critical archive for Precambrian carbonate factory evolution, microbial-environmental feedbacks, and early reservoir dynamics. This study advances understanding of late Precambrian Earth systems, bridging microbial processes, seawater chemistry, and tectono-climatic controls on carbonate preservation.
{"title":"Sedimentary model evolution and palaeoenvironmental significance of the Upper Ediacaran microbial dolomites","authors":"Yuan Zhou , Xuelian You , Qing Li , Zhuofeng Zhang , Qiang Du , Zhengyu Wei , Xinlong Li , Hui Zhou","doi":"10.1016/j.precamres.2025.107934","DOIUrl":"10.1016/j.precamres.2025.107934","url":null,"abstract":"<div><div>Microbial dolomites are extensively developed in the upper Ediacaran Dengying Formation (<em>ca</em> 551.1 to 542.0 Ma) in the Sichuan Basin, China. However, these microbial dolomites underwent complex depositional processes, and their sedimentary environments remain debated. In this study, the petrographic, mineralogical, and geochemical characteristics of microbial dolomites in the upper Ediacaran Dengying Formation are systematically analyzed. The microbial dolomites (stromatolites, thrombolites, oncoids, botryoidal dolomites) in the upper Ediacaran Dengying Formation demonstrate the interplay between microbial activity and environmental conditions in a shallow restricted platform. Microbial structural diversity reflects hydrodynamic-microbial synergy: stromatolites and botryoidal dolomites are formed in low-energy, high-activity settings; dispersed thrombolites are formed under weak microbial influence; layered/reticular thrombolites and oncoids are developed via particle aggregation in high-energy environments. Two transgressive–regressive cycles correlate with “dolomite sea” events: the first driven by global climate (evaporation, localized anoxia), the second by tectonic uplift (Tongwan Movement I), underscoring tectonics’ role in reservoir genesis. Geochemical indicators reflect post-glacial seawater stratification and weathering shifts, constraining environmental triggers for Ediacaran-Cambrian biotic complexity. Global comparisons reveal widespread microbial diagenesis during the Ediacaran, yet the Sichuan Basin exhibits unique tectono-climatic cyclicity. Although diagenesis obscures some geochemical signals, systematic analysis confirms the Dengying Formation as a critical archive for Precambrian carbonate factory evolution, microbial-environmental feedbacks, and early reservoir dynamics. This study advances understanding of late Precambrian Earth systems, bridging microbial processes, seawater chemistry, and tectono-climatic controls on carbonate preservation.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107934"},"PeriodicalIF":3.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221689","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}
Pub Date : 2025-09-27DOI: 10.1016/j.precamres.2025.107929
Lisa J. Zieman, M. Christopher Jenkins, Jacob E. Poletti
Komatiitic volcanic rocks are important hosts of Ni sulfide mineralization and record early Earth evolution; however, those in the well-studied Archean Wyoming Province have received little attention. Here, we elucidate the timing and petrogenesis of the Bradley Peak komatiitic volcanic rocks using field and textural observations, geochronology, and geochemistry. Detrital and igneous zircon U-Pb ages for two samples from previously undated units support published age determinations, placing the eruption age at 2.72 Ga. Stratigraphy of the volcanic flows was mapped and 36 samples including cumulates, greenschists, and spinifex-textured rocks were collected. Whole-rock geochemistry was used to classify the spinifex-textured samples as Al-undepleted komatiitic basalts (11–17 wt% MgO). Platinum-group element concentrations (n = 25) are like those in global Al-undepleted komatiitic basalts, and PGE/Ti ratios do not indicate the volcanic flows likely host sulfide mineralization. Initial εNd values of −0.5 to +4.7 (n = 16), indicate that these lavas were derived from a depleted mantle source and have negligible evolved crust contamination. The primary magma to the komatiitic basalt flows is estimated to have had 19 wt% MgO and be derived from ∼15 to 25 % mantle partial melting at 3–4 GPa. Trace element chemistry and thermodynamic modeling suggest the primary melt assimilated local banded iron formation. Although the Bradley Peak komatiitic basalts do not contain positive evidence of magmatic sulfide deposits, depleted Au in the flows suggests they could be source rocks for nearby orogenic gold deposits.
{"title":"Petrogenesis and mineralization potential of spinifex komatiitic basalts in the Bradley Peak greenstone terrane, Wyoming Province","authors":"Lisa J. Zieman, M. Christopher Jenkins, Jacob E. Poletti","doi":"10.1016/j.precamres.2025.107929","DOIUrl":"10.1016/j.precamres.2025.107929","url":null,"abstract":"<div><div>Komatiitic volcanic rocks are important hosts of Ni sulfide mineralization and record early Earth evolution; however, those in the well-studied Archean Wyoming Province have received little attention. Here, we elucidate the timing and petrogenesis of the Bradley Peak komatiitic volcanic rocks using field and textural observations, geochronology, and geochemistry. Detrital and igneous zircon U-Pb ages for two samples from previously undated units support published age determinations, placing the eruption age at 2.72 Ga. Stratigraphy of the volcanic flows was mapped and 36 samples including cumulates, greenschists, and spinifex-textured rocks were collected. Whole-rock geochemistry was used to classify the spinifex-textured samples as Al-undepleted komatiitic basalts (11–17 wt% MgO). Platinum-group element concentrations (n = 25) are like those in global Al-undepleted komatiitic basalts, and PGE/Ti ratios do not indicate the volcanic flows likely host sulfide mineralization. Initial ε<sub>Nd</sub> values of −0.5 to +4.7 (n = 16), indicate that these lavas were derived from a depleted mantle source and have negligible evolved crust contamination. The primary magma to the komatiitic basalt flows is estimated to have had 19 wt% MgO and be derived from ∼15 to 25 % mantle partial melting at 3–4 GPa. Trace element chemistry and thermodynamic modeling suggest the primary melt assimilated local banded iron formation. Although the Bradley Peak komatiitic basalts do not contain positive evidence of magmatic sulfide deposits, depleted Au in the flows suggests they could be source rocks for nearby orogenic gold deposits.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107929"},"PeriodicalIF":3.2,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159010","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}
Pub Date : 2025-09-27DOI: 10.1016/j.precamres.2025.107927
Adrien Vezinet , Javiera Flores-Rojas , Alexander V. Sobolev , Julien Léger , Aleksandr V. Chugunov , Valentina G. Batanova , Marlina A. Elburg , Axel Hofmann , Mélanie Balvay , Nouméa Paradis
Processes and mechanisms accounting for the stabilization of Archean (4.0–2.5 Ga) continental crust remain a matter of debate. Over the last decades, major efforts have been made to determine the chemical and isotopic composition of rocks belonging to the Tonalite-Trondhjemite-Granodiorite (TTG) suite, i.e. those forming the bulk of Archean continental crust, as well as late-Archean sanukitoids, the typical marker of cratonization. The extensive use of zircon elemental and isotopic signatures has indisputably been an unrivalled source of information; yet it has also biased interpretations through the prism of a single mineral, hence not reflecting the whole geological history of these magmas. To extend our understanding of early continent stabilization, a pivotal aspect of Earth’s evolution, a fresh perspective is necessary. Here, we present in-situ analyses of igneous apatite, Ca5(PO4)3(OH,Cl,F), from Archean granitoids exposed in the eastern Kaapvaal craton for major/trace elements and U–Pb/Sr isotopes. The trace element signatures of these apatite crystals, with a clear enrichment in LREE and an elevated LREE/HREE, resemble that of apatite from sanukitoids and Phanerozoic I-type granites, a signature which can be blurred at the whole-rock scale. We interpret this signature as indicating that the studied granitoids are formed via interaction between (i) a TTG melt, formed via partial melting of a subducting oceanic crust and (ii) a mantle component, causing chemical depletion of the mantle domain involved and thus production of long-lived and stable lithospheric keels pivotal in the long-term preservation of Archean lithosphere at the Earth’s surface. Therefore, the identification of this signature—in igneous apatite from Paleo to Meso-Archean TTGs of the eastern Kaapvaal—indicates an early onset of cratonization in this region.
{"title":"Igneous apatite geochemistry indicates early cratonization of continents","authors":"Adrien Vezinet , Javiera Flores-Rojas , Alexander V. Sobolev , Julien Léger , Aleksandr V. Chugunov , Valentina G. Batanova , Marlina A. Elburg , Axel Hofmann , Mélanie Balvay , Nouméa Paradis","doi":"10.1016/j.precamres.2025.107927","DOIUrl":"10.1016/j.precamres.2025.107927","url":null,"abstract":"<div><div>Processes and mechanisms accounting for the stabilization of Archean (4.0–2.5 Ga) continental crust remain a matter of debate. Over the last decades, major efforts have been made to determine the chemical and isotopic composition of rocks belonging to the Tonalite-Trondhjemite-Granodiorite (TTG) suite, i.e. those forming the bulk of Archean continental crust, as well as late-Archean sanukitoids, the typical marker of cratonization. The extensive use of zircon elemental and isotopic signatures has indisputably been an unrivalled source of information; yet it has also biased interpretations through the prism of a single mineral, hence not reflecting the whole geological history of these magmas. To extend our understanding of early continent stabilization, a pivotal aspect of Earth’s evolution, a fresh perspective is necessary. Here, we present in-situ analyses of igneous apatite, Ca<sub>5</sub>(PO<sub>4</sub>)<sub>3</sub>(OH,Cl,F), from Archean granitoids exposed in the eastern Kaapvaal craton for major/trace elements and U–Pb/Sr isotopes. The trace element signatures of these apatite crystals, with a clear enrichment in LREE and an elevated LREE/HREE, resemble that of apatite from sanukitoids and Phanerozoic I-type granites, a signature which can be blurred at the whole-rock scale. We interpret this signature as indicating that the studied granitoids are formed via interaction between (i) a TTG melt, formed via partial melting of a subducting oceanic crust and (ii) a mantle component, causing chemical depletion of the mantle domain involved and thus production of long-lived and stable lithospheric keels pivotal in the long-term preservation of Archean lithosphere at the Earth’s surface. Therefore, the identification of this signature—in igneous apatite from Paleo to Meso-Archean TTGs of the eastern Kaapvaal—indicates an early onset of cratonization in this region.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107927"},"PeriodicalIF":3.2,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145221693","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}
Pub Date : 2025-09-26DOI: 10.1016/j.precamres.2025.107933
Xiaoshuai Chen , Hongwei Kuang , Yongqing Liu , Daniel Paul Le Heron , Yuchong Wang , Nan Peng , Mingming Cui , Kening Qi
Glaciers were pivotal agents in shaping Cryogenian landscapes through erosional and depositional processes. Subglacial erosional forms serve as critical archives of glacial dynamics and thermal regimes, offering insights into paleoenvironmental interpretation and paleogeographic reconstruction. Cryogenian subglacial erosional forms are preserved on seven cratons globally, with China’s excellent example located in the Aksu-Wushi area of the northwestern Tarim Craton. A series of well-preserved erosional features of subglacial origin crop out, which until now have not been subject to systematic description or interpretation. This is redressed herein, and eight sites are surveyed in detail, enabling considerable insight into and unintegrated that have hindered research on Cryogenian glacial dynamics. In the Aksu-Wushi area, striations, grooves, p-forms, roches moutonnées, and glacial plucking morphologies, testify to both abrasion and meltwater processes at the ice-bedrock interface. A southwest-directed ice flow, with gradual southward deflection, is identified. Subglacial erosional forms and the overlying sedimentary successions documented in this study jointly reveal the depositional environmental evolution of the Yuermeinak Formation from subglacial to proglacial to post-glacial transgression, forming a complete record of continental ice sheet advance-retreat processes. The dynamic patterns and thermal regime of the Marinoan glacier further provide critical constraints for paleogeographic reconstruction. The consistent ice flow directions and sedimentary evolution observed in both the Yuermeinak Formation (Tarim) and Walsh Formation (Australia) collectively suggest that the Tarim was likely adjacent to the Australia during the Cryogenian period. The subglacial erosional forms and striated clasts at Aksu-Wushi area indicate a temperate glacial thermal regime during the latter stages of the snowball Earth event, compatible with a mid- to low-latitude paleogeographic setting. The massive gravel-bearing sandstone and siltstone with dropstones between the basal diamictite and overlying Ediacaran cap dolomite represents large-scale chemical weathering at the end of temperate glacier. Thus, paleo-glaciology can play a vital role in deep time paleogeographic reconstructions.
{"title":"Dynamics of Marinoan-age glaciers in NW Tarim, China","authors":"Xiaoshuai Chen , Hongwei Kuang , Yongqing Liu , Daniel Paul Le Heron , Yuchong Wang , Nan Peng , Mingming Cui , Kening Qi","doi":"10.1016/j.precamres.2025.107933","DOIUrl":"10.1016/j.precamres.2025.107933","url":null,"abstract":"<div><div>Glaciers were pivotal agents in shaping Cryogenian landscapes through erosional and depositional processes. Subglacial erosional forms serve as critical archives of glacial dynamics and thermal regimes, offering insights into paleoenvironmental interpretation and paleogeographic reconstruction. Cryogenian subglacial erosional forms are preserved on seven cratons globally, with China’s excellent example located in the Aksu-Wushi area of the northwestern Tarim Craton. A series of well-preserved erosional features of subglacial origin crop out, which until now have not been subject to systematic description or interpretation. This is redressed herein, and eight sites are surveyed in detail, enabling considerable insight into and unintegrated that have hindered research on Cryogenian glacial dynamics. In the Aksu-Wushi area, striations, grooves, p-forms, roches moutonnées, and glacial plucking morphologies, testify to both abrasion and meltwater processes at the ice-bedrock interface. A southwest-directed ice flow, with gradual southward deflection, is identified. Subglacial erosional forms and the overlying sedimentary successions documented in this study jointly reveal the depositional environmental evolution of the Yuermeinak Formation from subglacial to proglacial to post-glacial transgression, forming a complete record of continental ice sheet advance-retreat processes. The dynamic patterns and thermal regime of the Marinoan glacier further provide critical constraints for paleogeographic reconstruction. The consistent ice flow directions and sedimentary evolution observed in both the Yuermeinak Formation (Tarim) and Walsh Formation (Australia) collectively suggest that the Tarim was likely adjacent to the Australia during the Cryogenian period. The subglacial erosional forms and striated clasts at Aksu-Wushi area indicate a temperate glacial thermal regime during the latter stages of the snowball Earth event, compatible with a mid- to low-latitude paleogeographic setting. The massive gravel-bearing sandstone and siltstone with dropstones between the basal diamictite and overlying Ediacaran cap dolomite represents large-scale chemical weathering at the end of temperate glacier. Thus, paleo-glaciology can play a vital role in deep time paleogeographic reconstructions.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107933"},"PeriodicalIF":3.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145158883","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}
Pub Date : 2025-09-26DOI: 10.1016/j.precamres.2025.107925
Michel Macedo Meira , Simone Cerqueira Pereira Cruz , Elson Paiva Oliveira , Joseneusa Brilhante Rodrigues , Angela Beatriz de Menezes Leal , Cristiano Lana
New evidence from the northwestern São Francisco Craton sheds light on Paleoproterozoic tectonic evolution in the Minas-Bahia Orogen. Two metavolcanosedimentary sequences—the Boqueirão de Baixo and Chapada Grande formations—record stages of a Rhyacian orogenic system, characterized through integrated stratigraphic, petrographic, geochemical, geochronological, and isotopic data. The metavolcanic rocks of the Boqueirão de Baixo Formation consist mainly of fine-grained tholeiitic amphibolites, with juvenile zircon ƐHf(t) values (+3.78 to + 5.6), which crystallized at 2218 ± 18 Ma and were metamorphosed at 2020 ± 7 Ma. The Chapada Grande Formation comprises metasedimentary rocks and calc-alkaline to ultrapotassic mafic to intermediate metavolcanics, with crystallization ages between 2096 ± 20 Ma and 2066 ± 6 Ma and evolved isotopic signatures (ƐHf(t) −18.5 to −8.84). These formations developed in a continental arc setting along the eastern margin of the Bom Jesus da Lapa Terrane, with the metasedimentary rocks recording forearc, intra-arc, and passive margin deposition. Post-collisional sinistral strike-slip shear zones subsequently generated a pull-apart basin, which favored sediment deposition and the emplacement of the Guanambi Syenite Suite. This study refines the tectonic evolution of the Minas–Bahia Orogenic System and provides new insights into Rhyacian–Orosirian orogenic belts and the early assembly of the Columbia Supercontinent.
来自西北弗朗西斯科克拉通的新证据揭示了米纳斯-巴伊亚造山带的古元古代构造演化。boqueir o de Baixo组和Chapada Grande组两个变质火山-沉积层序记录了一个流纹造山系的阶段，通过综合地层、岩石学、地球化学、年代学和同位素数据进行了表征。boqueir o de Baixo组变质火山岩主要为细粒拉斑闪长岩，锆石ƐHf(t)值为+3.78 ~ + 5.6，在2218±18 Ma结晶，在2020±7 Ma变质。查帕达大组由变质沉积岩和钙碱性-超经典基性-中变质火山岩组成，结晶年龄在2096±20 Ma ~ 2066±6 Ma之间，演化的同位素特征为ƐHf(t)−18.5 ~−8.84。这些地层发育于Bom Jesus da Lapa地体东部边缘的大陆弧环境中，其变质沉积岩记录了弧前、弧内和被动边缘沉积。碰撞后的左旋走滑剪切带形成了拉分盆地，有利于沉积和瓜南壁正长岩套的侵位。该研究细化了米纳斯-巴伊亚造山系的构造演化，为研究流-奥造山带和哥伦比亚超大陆的早期组装提供了新的认识。
{"title":"Rhyacian (2218–2066 Ma) subduction-related volcanosedimentary accretion in the Western Bahia Orogenic Domain (São Francisco Craton, Brazil), and tectonic implications","authors":"Michel Macedo Meira , Simone Cerqueira Pereira Cruz , Elson Paiva Oliveira , Joseneusa Brilhante Rodrigues , Angela Beatriz de Menezes Leal , Cristiano Lana","doi":"10.1016/j.precamres.2025.107925","DOIUrl":"10.1016/j.precamres.2025.107925","url":null,"abstract":"<div><div>New evidence from the northwestern São Francisco Craton sheds light on Paleoproterozoic tectonic evolution in the Minas-Bahia Orogen. Two metavolcanosedimentary sequences—the Boqueirão de Baixo and Chapada Grande formations—record stages of a Rhyacian orogenic system, characterized through integrated stratigraphic, petrographic, geochemical, geochronological, and isotopic data. The metavolcanic rocks of the Boqueirão de Baixo Formation consist mainly of fine-grained tholeiitic amphibolites, with juvenile zircon Ɛ<sub>Hf(t)</sub> values (+3.78 to + 5.6), which crystallized at 2218 ± 18 Ma and were metamorphosed at 2020 ± 7 Ma. The Chapada Grande Formation comprises metasedimentary rocks and calc-alkaline to ultrapotassic mafic to intermediate metavolcanics, with crystallization ages between 2096 ± 20 Ma and 2066 ± 6 Ma and evolved isotopic signatures (Ɛ<sub>Hf(t)</sub> −18.5 to −8.84). These formations developed in a continental arc setting along the eastern margin of the Bom Jesus da Lapa Terrane, with the metasedimentary rocks recording forearc, intra-arc, and passive margin deposition. Post-collisional sinistral strike-slip shear zones subsequently generated a pull-apart basin, which favored sediment deposition and the emplacement of the Guanambi Syenite Suite. This study refines the tectonic evolution of the Minas–Bahia Orogenic System and provides new insights into Rhyacian–Orosirian orogenic belts and the early assembly of the Columbia Supercontinent.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107925"},"PeriodicalIF":3.2,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159009","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}
Pub Date : 2025-09-24DOI: 10.1016/j.precamres.2025.107928
Naomi Tucker , Samantha March , Martin Hand , Mitchell Bockmann , Patrick Kolesik
Geochronological data from detrital zircon, two generations of titanite, and authigenic sericite in glacial erratics transported to the Bunger Hills provide new insights into a deep subglacial basin in East Antarctica. Basin formation occurred during the late Mesoproterozoic, with diagenesis coinciding with granulite facies metamorphism in the underlying basement rocks. In line with previous studies, we interpret this basin to have formed as a rift sequence, but we extend this model by proposing that rifting was directly associated with Mesoproterozoic orogenesis, and that upper crustal extension was coupled with mid–lower-crustal ductile flow. The basin detritus was primarily sourced from a felsic magmatic-rich carapace emplaced at ca. 1180–1160 Ma. The authigenic mineralogy of the erratics, supported by chlorite thermometry and authigenic titanite geochronology, suggests that within the ensuing ca. 50–70 million years, the detritus was buried deeply and subjected to low-grade metamorphism (∼300 °C). Sericite ages complement the zircon and titanite dataset and reveal that the basin was largely unaffected by Cambrian tectonism, meaning that it was situated in thermomechanically stable crust and geographically distant to the major Gondwanan Indo–Australo–Antarctic suture. This study demonstrates the utility of coupled authigenic and detrital mineral geochronology in constraining sedimentary basin formation ages, and linking deep-crustal and near-surface processes.
{"title":"Authigenic titanite constraints on fast Mesoproterozoic basin formation in hot Antarctic crust","authors":"Naomi Tucker , Samantha March , Martin Hand , Mitchell Bockmann , Patrick Kolesik","doi":"10.1016/j.precamres.2025.107928","DOIUrl":"10.1016/j.precamres.2025.107928","url":null,"abstract":"<div><div>Geochronological data from detrital zircon, two generations of titanite, and authigenic sericite in glacial erratics transported to the Bunger Hills provide new insights into a deep subglacial basin in East Antarctica. Basin formation occurred during the late Mesoproterozoic, with diagenesis coinciding with granulite facies metamorphism in the underlying basement rocks. In line with previous studies, we interpret this basin to have formed as a rift sequence, but we extend this model by proposing that rifting was directly associated with Mesoproterozoic orogenesis, and that upper crustal extension was coupled with mid–lower-crustal ductile flow. The basin detritus was primarily sourced from a felsic magmatic-rich carapace emplaced at ca. 1180–1160 Ma. The authigenic mineralogy of the erratics, supported by chlorite thermometry and authigenic titanite geochronology, suggests that within the ensuing ca. 50–70 million years, the detritus was buried deeply and subjected to low-grade metamorphism (∼300 °C). Sericite ages complement the zircon and titanite dataset and reveal that the basin was largely unaffected by Cambrian tectonism, meaning that it was situated in thermomechanically stable crust and geographically distant to the major Gondwanan Indo–Australo–Antarctic suture. This study demonstrates the utility of coupled authigenic and detrital mineral geochronology in constraining sedimentary basin formation ages, and linking deep-crustal and near-surface processes.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107928"},"PeriodicalIF":3.2,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145159005","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}
Stromatolites are laminated biosedimentary structures that record long-standing interaction between environmental conditions and coevolving microbial life. Although they are among the oldest and most persistent forms of life on Earth, the extent to which environmental parameters affect their morphology and distribution remains poorly understood. In this study, we investigated the well-exposed stromatolites of the Ediacaran Salitre Formation (Irecê Basin, Brazil) to assess how physical sedimentary processes and early lithification dynamics controlled stromatolite growth and form. Through integrated sedimentological and petrographic analyses, we documented a stratigraphic transition from stratiform to columnar morphologies, which closely correlates with variations in hydrodynamic energy, sediment influx, and local relief. Our results demonstrate that increased hydrodynamic energy and detrital input promoted the development of columnar, often inclined or branched forms, whereas low-energy conditions allowed for the development of stratiform structures, especially within protected scour depressions. The occurrence of inclined, yet unbroken stromatolite columns and their alignment with the paleoflow indicators suggest growth under dynamic, high-energy conditions with weak or incomplete synsedimentary lithification. Despite the high-energy setting, grains are concentrated only within the intercolumnar spaces and are almost absent from the stromatolite laminae, suggesting that lamination resulted primarily from microbial carbonate precipitation rather than sediment trapping. Additionally, the internal lamination patterns and detrital material distribution reflect episodic sedimentation and microbial mat disruption, further emphasizing the sensitivity of stromatolite morphology to environmental changes. Our findings highlight that the stromatolites in the Salitre Formation provide a valuable snapshot of the intricate interplay between physical parameters and biological activity during the terminal Neoproterozoic.
{"title":"The role of environmental pressures on stromatolite morphology: Insights from the Ediacaran Salitre Formation, Irecê Basin, Brazil","authors":"Jhon Willy Lopes Afonso , Carolina Bedoya-Rueda , Sergio Caetano-Filho , Cristian Guacaneme , Guilherme Raffaelli , Mariane Candido , Kamilla Borges Amorim , Gustavo Macedo Paula-Santos , Marly Babinski , Ricardo Ivan Ferreira Trindade","doi":"10.1016/j.precamres.2025.107924","DOIUrl":"10.1016/j.precamres.2025.107924","url":null,"abstract":"<div><div>Stromatolites are laminated biosedimentary structures that record long-standing interaction between environmental conditions and coevolving microbial life. Although they are among the oldest and most persistent forms of life on Earth, the extent to which environmental parameters affect their morphology and distribution remains poorly understood. In this study, we investigated the well-exposed stromatolites of the Ediacaran Salitre Formation (Irecê Basin, Brazil) to assess how physical sedimentary processes and early lithification dynamics controlled stromatolite growth and form. Through integrated sedimentological and petrographic analyses, we documented a stratigraphic transition from stratiform to columnar morphologies, which closely correlates with variations in hydrodynamic energy, sediment influx, and local relief. Our results demonstrate that increased hydrodynamic energy and detrital input promoted the development of columnar, often inclined or branched forms, whereas low-energy conditions allowed for the development of stratiform structures, especially within protected scour depressions. The occurrence of inclined, yet unbroken stromatolite columns and their alignment with the paleoflow indicators suggest growth under dynamic, high-energy conditions with weak or incomplete synsedimentary lithification. Despite the high-energy setting, grains are concentrated only within the intercolumnar spaces and are almost absent from the stromatolite laminae, suggesting that lamination resulted primarily from microbial carbonate precipitation rather than sediment trapping. Additionally, the internal lamination patterns and detrital material distribution reflect episodic sedimentation and microbial mat disruption, further emphasizing the sensitivity of stromatolite morphology to environmental changes. Our findings highlight that the stromatolites in the Salitre Formation provide a valuable snapshot of the intricate interplay between physical parameters and biological activity during the terminal Neoproterozoic.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107924"},"PeriodicalIF":3.2,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107493","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}
Pub Date : 2025-09-16DOI: 10.1016/j.precamres.2025.107916
Garrett D. Brown , Maya L. Giannecchini , Cory M. Redman , Ian Z. Winkelstern , Dylan T. Wilmeth
The Lomagundi–Jatuli Event (LJE) was Earth’s longest (2.3–2.0 Ga) and largest (+5 to +30 ‰) positive δ13C excursion. The LJE’s exact causes remain uncertain, with various hypotheses involving increased organic carbon burial or restricted depositional facies. While many LJE carbonates have enriched δ13C signatures, several locations are closer to average values over Earth history (∼0‰), providing opportunities to test depositional models. For example, the ∼2.2 Ga Randville Dolomite in Michigan’s Upper Peninsula is less enriched in δ13C (0 to +3 ‰) compared to the neighboring Kona Dolomite (+5 to +10 ‰). Randville age constraints are broad but fall within the LJE (2.3–2.1 Ga), approximately coeval with Kona deposits (2.17 Ga). The Randville Dolomite contains extensive planar beds with minor scour-fill structures, slumps, and conglomerates, indicating a relatively calm depositional environment punctuated by storms and slope failures on an outer carbonate platform. Randville deposits contain a variety of microbialites including domal, inclined, nodular, and conical stromatolites, and potentially the oldest recorded dendrolites. The most likely explanation for δ13C differences between the Randville and Kona Dolomite involves depositional environments. Many enriched Kona deposits represent an evaporitic, marine basin, while Randville facies show little to no evidence for subaerial exposure or evaporation. Facies-dependent patterns between Randville and Kona Dolomites are mirrored in LJE carbonates across the Lake Superior region: formations with evaporites are consistently δ13C-enriched compared with other localities. These datasets support previous research indicating that at least during certain intervals, LJE excursions were not ubiquitous in all marine environments.
{"title":"Sedimentology, petrography, and carbon isotopes of the ∼2.2 Ga Randville Dolomite, Upper Peninsula of Michigan","authors":"Garrett D. Brown , Maya L. Giannecchini , Cory M. Redman , Ian Z. Winkelstern , Dylan T. Wilmeth","doi":"10.1016/j.precamres.2025.107916","DOIUrl":"10.1016/j.precamres.2025.107916","url":null,"abstract":"<div><div>The Lomagundi–Jatuli Event (LJE) was Earth’s longest (2.3–2.0 Ga) and largest (+5 to +30 ‰) positive δ<sup>13</sup>C excursion. The LJE’s exact causes remain uncertain, with various hypotheses involving increased organic carbon burial or restricted depositional facies. While many LJE carbonates have enriched δ<sup>13</sup>C signatures, several locations are closer to average values over Earth history (∼0‰), providing opportunities to test depositional models. For example, the ∼2.2 Ga Randville Dolomite in Michigan’s Upper Peninsula is less enriched in δ<sup>13</sup>C (0 to +3 ‰) compared to the neighboring Kona Dolomite (+5 to +10 ‰). Randville age constraints are broad but fall within the LJE (2.3–2.1 Ga), approximately coeval with Kona deposits (2.17 Ga). The Randville Dolomite contains extensive planar beds with minor scour-fill structures, slumps, and conglomerates, indicating a relatively calm depositional environment punctuated by storms and slope failures on an outer carbonate platform. Randville deposits contain a variety of microbialites including domal, inclined, nodular, and conical stromatolites, and potentially the oldest recorded dendrolites. The most likely explanation for δ<sup>13</sup>C differences between the Randville and Kona Dolomite involves depositional environments. Many enriched Kona deposits represent an evaporitic, marine basin, while Randville facies show little to no evidence for subaerial exposure or evaporation. Facies-dependent patterns between Randville and Kona Dolomites are mirrored in LJE carbonates across the Lake Superior region: formations with evaporites are consistently δ<sup>13</sup>C-enriched compared with other localities. These datasets support previous research indicating that at least during certain intervals, LJE excursions were not ubiquitous in all marine environments.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107916"},"PeriodicalIF":3.2,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145107492","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}
Pub Date : 2025-09-12DOI: 10.1016/j.precamres.2025.107917
Elizabeth A. Bell
Much of the Proterozoic crust in the Colorado River Extensional Corridor, southwestern USA has been extensively heated during Basin and Range extension. However, most thermochronology has been undertaken on the southern, most extended part of the corridor, with limited results suggesting less intense heating in the northern corridor, such that pre-Cenozoic medium-temperature Pb loss may be preserved in places. This study reports zircon and apatite U-Pb dating in the eastern region of the Paleoproterozoic Davis Dam Granite. This study searched for evidence of post-crystallization Pb loss in a region close to Miocene volcanic intrusions and faulting. Although zircon from three samples have average ages overall similar within error, with an overall average age 1665 ± 30 Ma, a small population of > 1.7 Ga zircon in one sample may be xenocrystic. In all units, some 1.65–1.58 Ga Pb loss is suggested from a tail of younger concordant zircon ages, potentially reflecting metamorphic alteration during the Mazatzal orogeny. Variations among the three samples in zircon discordance behavior, overprinted/altered cathodoluminescence zoning, and the assemblages of secondary minerals filling cracks and void space in the zircon grains suggests geographic variation within the granite in post-crystallization alteration. Apatite have concordant ages ranging 1.7 to 1.2 Ga, with an average age of 1440 ± 132 Ma. The Davis Dam Granite preserves one or more post-Ivanpah and post-Mazatzal metamorphic events in the eastern Mojave province without overprinting by heating during Cenozoic Basin and Range extension in the northern Colorado River Extensional Corridor. Similar studies of older granitoids and their accessory minerals may better elucidate the Mesoproterozoic history of the northern Colorado River Extensional Corridor, its relationship with wider regional Mesoproterozoic tectonism, and the extent of Cenozoic overprinting.
{"title":"Mesoproterozoic Pb loss in the 1.67 Ga Davis Dam Granite, northern Colorado River Extensional Corridor, USA","authors":"Elizabeth A. Bell","doi":"10.1016/j.precamres.2025.107917","DOIUrl":"10.1016/j.precamres.2025.107917","url":null,"abstract":"<div><div>Much of the Proterozoic crust in the Colorado River Extensional Corridor, southwestern USA has been extensively heated during Basin and Range extension. However, most thermochronology has been undertaken on the southern, most extended part of the corridor, with limited results suggesting less intense heating in the northern corridor, such that pre-Cenozoic medium-temperature Pb loss may be preserved in places. This study reports zircon and apatite U-Pb dating in the eastern region of the Paleoproterozoic Davis Dam Granite. This study searched for evidence of post-crystallization Pb loss in a region close to Miocene volcanic intrusions and faulting. Although zircon from three samples have average ages overall similar within error, with an overall average age 1665 ± 30 Ma, a small population of > 1.7 Ga zircon in one sample may be xenocrystic. In all units, some 1.65–1.58 Ga Pb loss is suggested from a tail of younger concordant zircon ages, potentially reflecting metamorphic alteration during the Mazatzal orogeny. Variations among the three samples in zircon discordance behavior, overprinted/altered cathodoluminescence zoning, and the assemblages of secondary minerals filling cracks and void space in the zircon grains suggests geographic variation within the granite in post-crystallization alteration. Apatite have concordant ages ranging 1.7 to 1.2 Ga, with an average age of 1440 ± 132 Ma. The Davis Dam Granite preserves one or more post-Ivanpah and post-Mazatzal metamorphic events in the eastern Mojave province without overprinting by heating during Cenozoic Basin and Range extension in the northern Colorado River Extensional Corridor. Similar studies of older granitoids and their accessory minerals may better elucidate the Mesoproterozoic history of the northern Colorado River Extensional Corridor, its relationship with wider regional Mesoproterozoic tectonism, and the extent of Cenozoic overprinting.</div></div>","PeriodicalId":49674,"journal":{"name":"Precambrian Research","volume":"430 ","pages":"Article 107917"},"PeriodicalIF":3.2,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145050238","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}
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