Alexander J. Krause, Graham A Shields, Robert J. Newton, Benjamin J. W. Mills
Understanding the long-term variance of seawater sulfate concentrations ([SO 4 2- ] sw ) is critical to understanding the dynamic relationship between the sulfur, carbon, calcium, and oxygen cycles, and their influence on Earth's habitability. Here, we explore how [SO 4 2- ] sw has changed throughout the Phanerozoic, and its impact on other elemental cycles. We do this by utilising the biogeochemical box model GEOCARBSULFOR. The model suggests that [SO 4 2- ] sw rose throughout the Paleozoic, declined during the Mesozoic, and then rose once more in the Cenozoic, generally matching geochemical proxies. Atmospheric oxygen mirrors [SO 4 2- ] sw changes during the Paleozoic and Mesozoic, but intriguingly, decouples during the Cenozoic. We further explored controls on [SO 4 2- ] sw by modifying the modelled gypsum fluxes via the incorporation of evaporite data from the geological record. We find that forcing gypsum burial with the observed evaporite deposition data causes the model to better match proxy records at some times, but worsens predictions at others. Finally, we investigate model reliance on a prescribed record of marine calcium concentrations, finding that it is a dominant control on modelled Phanerozoic [SO 4 2- ] sw , and that removing this control seriously degrades model predictions. We conclude that no model can yet simulate a reasonable evolution of both the calcium and sulfur cycles. Thematic collection: This article is part of the Sulfur in the Earth system collection available at: https://www.lyellcollection.org/topic/collections/sulfur-in-the-earth-system Supplementary material: https://doi.org/10.6084/m9.figshare.c.7164928
{"title":"Modelling sulfate concentrations in the global ocean through Phanerozoic time","authors":"Alexander J. Krause, Graham A Shields, Robert J. Newton, Benjamin J. W. Mills","doi":"10.1144/jgs2023-184","DOIUrl":"https://doi.org/10.1144/jgs2023-184","url":null,"abstract":"\u0000 Understanding the long-term variance of seawater sulfate concentrations ([SO\u0000 4\u0000 2-\u0000 ]\u0000 sw\u0000 ) is critical to understanding the dynamic relationship between the sulfur, carbon, calcium, and oxygen cycles, and their influence on Earth's habitability. Here, we explore how [SO\u0000 4\u0000 2-\u0000 ]\u0000 sw\u0000 has changed throughout the Phanerozoic, and its impact on other elemental cycles. We do this by utilising the biogeochemical box model GEOCARBSULFOR. The model suggests that [SO\u0000 4\u0000 2-\u0000 ]\u0000 sw\u0000 rose throughout the Paleozoic, declined during the Mesozoic, and then rose once more in the Cenozoic, generally matching geochemical proxies. Atmospheric oxygen mirrors [SO\u0000 4\u0000 2-\u0000 ]\u0000 sw\u0000 changes during the Paleozoic and Mesozoic, but intriguingly, decouples during the Cenozoic. We further explored controls on [SO\u0000 4\u0000 2-\u0000 ]\u0000 sw\u0000 by modifying the modelled gypsum fluxes via the incorporation of evaporite data from the geological record. We find that forcing gypsum burial with the observed evaporite deposition data causes the model to better match proxy records at some times, but worsens predictions at others. Finally, we investigate model reliance on a prescribed record of marine calcium concentrations, finding that it is a dominant control on modelled Phanerozoic [SO\u0000 4\u0000 2-\u0000 ]\u0000 sw\u0000 , and that removing this control seriously degrades model predictions. We conclude that no model can yet simulate a reasonable evolution of both the calcium and sulfur cycles.\u0000 \u0000 \u0000 Thematic collection:\u0000 This article is part of the Sulfur in the Earth system collection available at:\u0000 https://www.lyellcollection.org/topic/collections/sulfur-in-the-earth-system\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7164928\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"156 S318","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140731512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuxuan Wang, Paul Wignall, Yijun Xiong, D. Loydell, Jeffrey Peakall, Jaco H. Baas, Benjamin J. W. Mills, S. Poulton
The early Silurian Llandovery–Wenlock boundary interval was marked by significant marine perturbations and biotic turnover, culminating in the Ireviken Extinction Event (IEE) and the Early Sheinwoodian Carbon Isotope Excursion (ESCIE). Here, we apply multiple independent redox proxies to the early Wenlock Buttington section, which was deposited in a mid-shelf location in the Welsh Basin, UK. To account for regional geochemical variability in marine sediments due to factors such as sediment provenance, we first define oxic baseline values for the Welsh basin, utilizing deeper water, well-oxygenated intervals of late Llandovery age. Our approach documents unstable, oscillating redox conditions on the mid shelf at Buttington. We suggest that these dynamic redox fluctuations are likely to relate to changes in the position of the chemocline or a migrating oxygen minimum zone. Benthic biota such as trilobites, brachiopods, bivalves and gastropods appear to have been relatively unaffected by fluctuating oxic-ferruginous conditions, but were more severely impacted by the development of euxinia, highlighting the inhibiting role of toxic sulfides. By contrast, the redox perturbations appear to have placed extreme stress on graptolites, causing many extinction losses regardless of the specific development of euxinia. Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system Supplementary material: https://doi.org/10.6084/m9.figshare.c.7165009
早志留纪兰德发现期-文洛克边界区间的特点是显著的海洋扰动和生物更替，最终导致了伊雷维肯大灭绝事件（IEE）和早志留纪碳同位素激变（ESCIE）。在此，我们将多个独立的氧化还原代用指标应用于沉积于英国威尔士盆地中陆的早期温洛克布廷顿剖面。为了考虑沉积物产地等因素造成的海洋沉积物的区域地球化学变异性，我们首先利用兰德塞斯晚期的深水富氧区间，定义了威尔士盆地的氧化基线值。我们的方法记录了布廷顿大陆架中部不稳定的、振荡的氧化还原条件。我们认为，这些动态氧化还原波动可能与化学跃层位置的变化或氧最小区的迁移有关。底栖生物群（如三叶虫、腕足类、双壳类和腹足类）似乎相对不受缺氧-铁锈色波动条件的影响，但却受到缺氧状态发展的严重影响，这凸显了有毒硫化物的抑制作用。相比之下，氧化还原扰动似乎对石龙子造成了极大的压力，导致许多石龙子灭绝，而与具体的蜕皮发育无关。 专题文集：本文是《中古生代地球系统的化学演化与生物响应》（Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response）文集的一部分，可从以下网站获取： https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system 补充材料： https://doi.org/10.6084/m9.figshare.c.7165009
{"title":"Marine redox dynamics and biotic response to the mid-Silurian Ireviken Extinction Event in a mid-shelf setting","authors":"Yuxuan Wang, Paul Wignall, Yijun Xiong, D. Loydell, Jeffrey Peakall, Jaco H. Baas, Benjamin J. W. Mills, S. Poulton","doi":"10.1144/jgs2023-155","DOIUrl":"https://doi.org/10.1144/jgs2023-155","url":null,"abstract":"The early Silurian Llandovery–Wenlock boundary interval was marked by significant marine perturbations and biotic turnover, culminating in the Ireviken Extinction Event (IEE) and the Early Sheinwoodian Carbon Isotope Excursion (ESCIE). Here, we apply multiple independent redox proxies to the early Wenlock Buttington section, which was deposited in a mid-shelf location in the Welsh Basin, UK. To account for regional geochemical variability in marine sediments due to factors such as sediment provenance, we first define oxic baseline values for the Welsh basin, utilizing deeper water, well-oxygenated intervals of late Llandovery age. Our approach documents unstable, oscillating redox conditions on the mid shelf at Buttington. We suggest that these dynamic redox fluctuations are likely to relate to changes in the position of the chemocline or a migrating oxygen minimum zone. Benthic biota such as trilobites, brachiopods, bivalves and gastropods appear to have been relatively unaffected by fluctuating oxic-ferruginous conditions, but were more severely impacted by the development of euxinia, highlighting the inhibiting role of toxic sulfides. By contrast, the redox perturbations appear to have placed extreme stress on graptolites, causing many extinction losses regardless of the specific development of euxinia.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at:\u0000 https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7165009\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"24 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140729051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Zhu 3 Depression is located at the transition between the South China Sea (SCS) and the South China Block. The Cenozoic structure reflects the dynamic background of the SCS. In this paper, 3D seismic data and log data are used to study the structural evolution of the Zhu 3 Depression. Based on fault activity and the distribution of stratum thickness, the Cenozoic rift deformation characteristics and the migration of the depocenter are defined. Spatial and temporal differences in the Cenozoic structure of the Zhu 3 Depression are due to the influence of pre-existing faults and regional stresses. The results show that there are three populations of faults with NE-, EW- and NW-striking in the Zhu 3 Depression. The NE-striking faults are mainly large-scale boundary faults. The W-E-striking faults are small and are activated in the late stages. The NW-striking faults are continuous at depth but are en-echelon and parallel to each other at shallow depth. On the basis of the above, we found that the NE- and NW-striking pre-existing faults divide the Zhu 3 Depression into different structural zones and control differences in deformation in the basin. Controlled by regional plate interactions and the Red River Fault Zone, the regional stress direction changes clockwise from NW-trending during the Paleocene to the NE-trending during the middle Miocene. These findings are expected to contribute to a better understanding of the evolution of the entire South China Sea. Thematic collection: This article is part of the Emerging knowledge on the tectonics of the South China Sea collection available at: https://www.lyellcollection.org/topic/collections/south-china-sea
{"title":"The Cenozoic structure of the Zhu 3 Depression in the Pearl River Mouth Basin and its response to the dynamic background of the South China Sea","authors":"Wei Li, Mingyue Cao, Di Wang, Hui Li, Dawei Fu, Xingpeng Chen, Meifang Meng, Wanqiu Wu, Jia Li, Yong Chen","doi":"10.1144/jgs2023-119","DOIUrl":"https://doi.org/10.1144/jgs2023-119","url":null,"abstract":"The Zhu 3 Depression is located at the transition between the South China Sea (SCS) and the South China Block. The Cenozoic structure reflects the dynamic background of the SCS. In this paper, 3D seismic data and log data are used to study the structural evolution of the Zhu 3 Depression. Based on fault activity and the distribution of stratum thickness, the Cenozoic rift deformation characteristics and the migration of the depocenter are defined. Spatial and temporal differences in the Cenozoic structure of the Zhu 3 Depression are due to the influence of pre-existing faults and regional stresses. The results show that there are three populations of faults with NE-, EW- and NW-striking in the Zhu 3 Depression. The NE-striking faults are mainly large-scale boundary faults. The W-E-striking faults are small and are activated in the late stages. The NW-striking faults are continuous at depth but are en-echelon and parallel to each other at shallow depth. On the basis of the above, we found that the NE- and NW-striking pre-existing faults divide the Zhu 3 Depression into different structural zones and control differences in deformation in the basin. Controlled by regional plate interactions and the Red River Fault Zone, the regional stress direction changes clockwise from NW-trending during the Paleocene to the NE-trending during the middle Miocene. These findings are expected to contribute to a better understanding of the evolution of the entire South China Sea.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Emerging knowledge on the tectonics of the South China Sea collection available at:\u0000 https://www.lyellcollection.org/topic/collections/south-china-sea\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140736808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Suárez, Pablo D. González, S. Oriolo, Martín Parada, Miguel E. Ramos, M. Ghiglione, C. Zaffarana, Juan F. Albano, Juan J. Ponce
The Devonian to early Carboniferous western margin of Patagonia (South America) includes a NW-SE-trending magmatic arc associated with a palaeo NE-dipping subduction zone. Along the Andean region of southern Patagonia, the Eastern Andean Metamorphic Complex (EAMC) developed in a forearc position, consisting of a succession of very low- to low-grade metaturbidite-metabasic rocks emplaced from the Devonian to Carboniferous periods. There are significant uncertainties surrounding this metamorphic complex, mainly related to the tectonosedimentary setting of the basin and subsequent conditions of deformation and metamorphism, which hinder our understanding of the orogenic architecture. To reveal the link between tectonics and metamorphism, we conducted a structural analysis and sampled metapelites to measure illite crystallinity along a regional structural cross-section in the EAMC. Our analysis reveals broadly Lower to Upper Anchizonal metamorphism which is roughly synchronous with deformation along northward-verging thrusts. These findings support the development of a forearc hyperextended basin that was subsequently closed during the Gondwanide orogeny (late Paleozoic), a model that reconciles previous proposals suggesting passive margin vs. back-arc basin models. This closure led to the emplacement of suprasubduction zone ophiolites and turbidites over the continent through landward migration of brittle-ductile reverse shear zones. Thematic collection: This article is part of the Ophiolites, melanges and blueschists collection available at: https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists Supplementary material: https://doi.org/10.6084/m9.figshare.c.7160849
{"title":"Thrust-related metamorphism in Carboniferous slates of southern Patagonia (South America): The fate of forearc successions","authors":"R. Suárez, Pablo D. González, S. Oriolo, Martín Parada, Miguel E. Ramos, M. Ghiglione, C. Zaffarana, Juan F. Albano, Juan J. Ponce","doi":"10.1144/jgs2023-173","DOIUrl":"https://doi.org/10.1144/jgs2023-173","url":null,"abstract":"The Devonian to early Carboniferous western margin of Patagonia (South America) includes a NW-SE-trending magmatic arc associated with a palaeo NE-dipping subduction zone. Along the Andean region of southern Patagonia, the Eastern Andean Metamorphic Complex (EAMC) developed in a forearc position, consisting of a succession of very low- to low-grade metaturbidite-metabasic rocks emplaced from the Devonian to Carboniferous periods. There are significant uncertainties surrounding this metamorphic complex, mainly related to the tectonosedimentary setting of the basin and subsequent conditions of deformation and metamorphism, which hinder our understanding of the orogenic architecture. To reveal the link between tectonics and metamorphism, we conducted a structural analysis and sampled metapelites to measure illite crystallinity along a regional structural cross-section in the EAMC. Our analysis reveals broadly Lower to Upper Anchizonal metamorphism which is roughly synchronous with deformation along northward-verging thrusts. These findings support the development of a forearc hyperextended basin that was subsequently closed during the Gondwanide orogeny (late Paleozoic), a model that reconciles previous proposals suggesting passive margin vs. back-arc basin models. This closure led to the emplacement of suprasubduction zone ophiolites and turbidites over the continent through landward migration of brittle-ductile reverse shear zones.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Ophiolites, melanges and blueschists collection available at:\u0000 https://www.lyellcollection.org/topic/collections/ophiolites-melanges-and-blueschists\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7160849\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"44 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140743082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Neil S. Davies, William J. McMahon, Christopher M. Berry
The evolution of trees and forests through the Devonian Period fundamentally changed Earth's land biosphere, as well as impacting physical environments and geomorphology by stabilizing sediment and interacting with flowing air and water. From the mid Givetian Age onwards, lignophyte flora are known to have been key parts of the machinery in the ‘Devonian Landscape Factory’, but the impact of earlier forests, dominated by less woody cladoxylopsids, are not as well understood. In this paper we report evidence for a previously unrecognized cladoxylopsid forest landscape, archived within the Eifelian Hangman Sandstone Formation of Somerset and Devon, SW England. This unit has previously been considered palaeobotanically depauperate but is here shown to contain the earliest fossil evidence for such trees in the British record, as well as the oldest known evidence globally for the relative position of standing trees: in common parlance a ‘fossil forest’. In addition to abundant fossil material attributable to the cladoxylopsid tree Calamophyton , and other early Middle Devonian flora, the sedimentary context of the plant remains sheds light on the biogeomorphic impacts of these earliest forests. The trees colonized a sizeable distributive fluvial system (DFS) that was prone to seasonal disturbance events. The nature of the sedimentary system has created a bias to those facies where biogeomorphic signatures are most frequently recorded (from the distal parts of the system), but across the DFS there is evidence of plant-sediment interactions in the form of vegetation-induced sedimentary structures, rooting features, and accumulations of plant debris. Plant remains are also found in nearshore facies adjacent to the DFS, attesting to the development of a novel non-marine/marine teleconnection from the production and export of new biological sedimentary particles. The Hangman Sandstone Formation is illustrative of the revolutionary power of cladoxylopsid trees as biogeomorphic agents, forming densely spaced forests and shedding exceptionally abundant plant debris, whilst also impacting local landforms and sediment accumulations and profoundly changing landform resilience against flood disturbance events. These findings provide evidence that the Eifelian Stage (393.3-387.7 Ma) marks the onset of tree-driven changes to physical environments that would forever change Earth's non-marine landscapes and biosphere. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7084873
{"title":"Earth's earliest forest: fossilized trees and vegetation-induced sedimentary structures from the Middle Devonian (Eifelian) Hangman Sandstone Formation, Somerset and Devon, SW England","authors":"Neil S. Davies, William J. McMahon, Christopher M. Berry","doi":"10.1144/jgs2023-204","DOIUrl":"https://doi.org/10.1144/jgs2023-204","url":null,"abstract":"\u0000 The evolution of trees and forests through the Devonian Period fundamentally changed Earth's land biosphere, as well as impacting physical environments and geomorphology by stabilizing sediment and interacting with flowing air and water. From the mid Givetian Age onwards, lignophyte flora are known to have been key parts of the machinery in the ‘Devonian Landscape Factory’, but the impact of earlier forests, dominated by less woody cladoxylopsids, are not as well understood. In this paper we report evidence for a previously unrecognized cladoxylopsid forest landscape, archived within the Eifelian Hangman Sandstone Formation of Somerset and Devon, SW England. This unit has previously been considered palaeobotanically depauperate but is here shown to contain the earliest fossil evidence for such trees in the British record, as well as the oldest known evidence globally for the relative position of standing trees: in common parlance a ‘fossil forest’. In addition to abundant fossil material attributable to the cladoxylopsid tree\u0000 Calamophyton\u0000 , and other early Middle Devonian flora, the sedimentary context of the plant remains sheds light on the biogeomorphic impacts of these earliest forests. The trees colonized a sizeable distributive fluvial system (DFS) that was prone to seasonal disturbance events. The nature of the sedimentary system has created a bias to those facies where biogeomorphic signatures are most frequently recorded (from the distal parts of the system), but across the DFS there is evidence of plant-sediment interactions in the form of vegetation-induced sedimentary structures, rooting features, and accumulations of plant debris. Plant remains are also found in nearshore facies adjacent to the DFS, attesting to the development of a novel non-marine/marine teleconnection from the production and export of new biological sedimentary particles. The Hangman Sandstone Formation is illustrative of the revolutionary power of cladoxylopsid trees as biogeomorphic agents, forming densely spaced forests and shedding exceptionally abundant plant debris, whilst also impacting local landforms and sediment accumulations and profoundly changing landform resilience against flood disturbance events. These findings provide evidence that the Eifelian Stage (393.3-387.7 Ma) marks the onset of tree-driven changes to physical environments that would forever change Earth's non-marine landscapes and biosphere.\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7084873\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139957208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shijie Zhang, Y. Najman, Xiumian Hu, Andrew Carter, Chris Mark, Wei-Guang Xue
Regional variations in the evolution of the Tibetan plateau has important implications for our understanding of crustal deformation processes. The evolution of the NW margin of the plateau and its transition to the Pamir to the west is one under-studied region. We focus on this region with a multi-technique detrital study of two sedimentary sections in the Tarim Basin. Our provenance data show that an appreciable component of the detrital material in the sedimentary sections was derived from the Songpan-Ganzi – Tianshuihai composite terrane, with some contribution from the Karakoram and/or the West Qiangtang. Given the proximity of the West Kunlun to the sedimentary sections under study, and its long history of exhumation, this terrane in all likelihood also contributed to the studied successions. Our thermochronological data record phases of exhumation in the hinterland in the Triassic, Early Cretaceous and Oligo-Miocene. Similar to the Pamir, the Triassic and Oligo-Miocene periods of exhumation are attributed to the Cimmerian and Himalayan orogenies respectively. The Early Cretaceous signal may reflect the distal effects of the Lhasa–Qiangtang collision. Coevality with deformation in Pamir suggests a coupled geodynamic system, with retroarc deformation associated with NeoTethyan subduction in the west, and terrane accretion in the east. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7040686
{"title":"Constraining the exhumation history of the north-western margin of Tibet with a comparison to the adjacent Pamir","authors":"Shijie Zhang, Y. Najman, Xiumian Hu, Andrew Carter, Chris Mark, Wei-Guang Xue","doi":"10.1144/jgs2023-198","DOIUrl":"https://doi.org/10.1144/jgs2023-198","url":null,"abstract":"Regional variations in the evolution of the Tibetan plateau has important implications for our understanding of crustal deformation processes. The evolution of the NW margin of the plateau and its transition to the Pamir to the west is one under-studied region. We focus on this region with a multi-technique detrital study of two sedimentary sections in the Tarim Basin. Our provenance data show that an appreciable component of the detrital material in the sedimentary sections was derived from the Songpan-Ganzi – Tianshuihai composite terrane, with some contribution from the Karakoram and/or the West Qiangtang. Given the proximity of the West Kunlun to the sedimentary sections under study, and its long history of exhumation, this terrane in all likelihood also contributed to the studied successions. Our thermochronological data record phases of exhumation in the hinterland in the Triassic, Early Cretaceous and Oligo-Miocene. Similar to the Pamir, the Triassic and Oligo-Miocene periods of exhumation are attributed to the Cimmerian and Himalayan orogenies respectively. The Early Cretaceous signal may reflect the distal effects of the Lhasa–Qiangtang collision. Coevality with deformation in Pamir suggests a coupled geodynamic system, with retroarc deformation associated with NeoTethyan subduction in the west, and terrane accretion in the east.\u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7040686\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"52 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139594591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nuerkanati Madayipu, Huan Li, S. M. Elatikpo, M. Ghaderi, Rub'son N'nahano-Ruhindwa Heritier, Xiao-Jun Hu, Han Zheng, Qian-hong Wu
The appearance of hydrous magmas and the following separation of volatile-rich fluids through hydrothermal alteration are intricately linked to forming granitic rare-metal deposits, the principal source of worldwide Li, Be, Nb, Ta, and Cs production. The lack of mineralogical information from the developing magmatic-hydrothermal system has, however, prevented a thorough comprehension of these processes. Apatite occurs as an accessory mineral in the metasedimentary (schist)–magmatic (muscovite monzogranite)–pegmatite (ore-free/ore-bearing pegmatite) rocks in Mufushan Complex (MFSC) rare-metal ore field of the northeastern Hunan, South China, potentially providing insights into Nb-Ta-(Li-Be-Cs) mineralization. To demonstrate that apatite can potentially record the magmatic-hydrothermal evolution of metasedimentary-magmatic-pegmatite systems, this study presents a combined textural and geochemical study of apatite from the MFSC granitic pegmatite-type rare-metal mineralization. The MFSC apatite textures and compositions have changed (i.e., post-crystallization alteration) since it first crystallized. Apatite from the schist shows homogeneous rim or homogeneous textures with crack or inclusion (S-ap1) and patch core (S-ap2), indicative of a magmatic-hydrothermal origin. Apatite from the muscovite monzogranite (G-ap) displays altered and distinctive core-rim textures, with visible voids, mineral inclusions, and cracks, suggestive of overprinting of early-magmatism texture by hydrothermal fluid. However, compared to the S-ap1, S-ap2, and G-ap, the pegmatite apatite shows more complicated textures, i.e., P-ap1: homogeneous bright and dark areas, and P-ap2: replacement texture involving alteration rim, growth zonation, patchy, and complex zoning patterns. P-ap1 underwent early magmatism and weaker post-hydrothermal overprinting, P-ap2 reflects a magmatic-hydrothermal product. S-ap1 and S-ap2 yield lower intercept ages of 130.6 ± 1.8 Ma and 128.4 ± 3.8 Ma, respectively, which are consistent with the transitional age of magmatic-hydrothermal metallogenic environment in northeastern Hunan. The G-ap and P-ap1 yield older ages of 136.3 ± 2.8 Ma and 141.3 ± 6.7 Ma, respectively, which are corresponding to the age of magmatic early-stage (Nb-Ta)-mineralization within their uncertainty in the northeastern Hunan. The Sr isotopic composition of apatite provide evidence for the provenance of the MFSC batholith in the rare-metal metallogenesis of the Lengjiaxi Group. Therefore, we hypothesize that apatite in granitic rare-metal deposits within metasedimentary-magmatic-pegmatite systems might be employed as a viable proxy to explore fluid exsolution and hydrothermal alteration signature concerning its textures and geochemical fingerprints. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7038699
{"title":"Tracing fluid exsolution and hydrothermal alteration signature of the Mufushan Nb-Ta-(Li-Be-Cs) deposit, South China: An apatite perspective","authors":"Nuerkanati Madayipu, Huan Li, S. M. Elatikpo, M. Ghaderi, Rub'son N'nahano-Ruhindwa Heritier, Xiao-Jun Hu, Han Zheng, Qian-hong Wu","doi":"10.1144/jgs2023-087","DOIUrl":"https://doi.org/10.1144/jgs2023-087","url":null,"abstract":"The appearance of hydrous magmas and the following separation of volatile-rich fluids through hydrothermal alteration are intricately linked to forming granitic rare-metal deposits, the principal source of worldwide Li, Be, Nb, Ta, and Cs production. The lack of mineralogical information from the developing magmatic-hydrothermal system has, however, prevented a thorough comprehension of these processes. Apatite occurs as an accessory mineral in the metasedimentary (schist)–magmatic (muscovite monzogranite)–pegmatite (ore-free/ore-bearing pegmatite) rocks in Mufushan Complex (MFSC) rare-metal ore field of the northeastern Hunan, South China, potentially providing insights into Nb-Ta-(Li-Be-Cs) mineralization. To demonstrate that apatite can potentially record the magmatic-hydrothermal evolution of metasedimentary-magmatic-pegmatite systems, this study presents a combined textural and geochemical study of apatite from the MFSC granitic pegmatite-type rare-metal mineralization. The MFSC apatite textures and compositions have changed (i.e., post-crystallization alteration) since it first crystallized. Apatite from the schist shows homogeneous rim or homogeneous textures with crack or inclusion (S-ap1) and patch core (S-ap2), indicative of a magmatic-hydrothermal origin. Apatite from the muscovite monzogranite (G-ap) displays altered and distinctive core-rim textures, with visible voids, mineral inclusions, and cracks, suggestive of overprinting of early-magmatism texture by hydrothermal fluid. However, compared to the S-ap1, S-ap2, and G-ap, the pegmatite apatite shows more complicated textures, i.e., P-ap1: homogeneous bright and dark areas, and P-ap2: replacement texture involving alteration rim, growth zonation, patchy, and complex zoning patterns. P-ap1 underwent early magmatism and weaker post-hydrothermal overprinting, P-ap2 reflects a magmatic-hydrothermal product. S-ap1 and S-ap2 yield lower intercept ages of 130.6 ± 1.8 Ma and 128.4 ± 3.8 Ma, respectively, which are consistent with the transitional age of magmatic-hydrothermal metallogenic environment in northeastern Hunan. The G-ap and P-ap1 yield older ages of 136.3 ± 2.8 Ma and 141.3 ± 6.7 Ma, respectively, which are corresponding to the age of magmatic early-stage (Nb-Ta)-mineralization within their uncertainty in the northeastern Hunan. The Sr isotopic composition of apatite provide evidence for the provenance of the MFSC batholith in the rare-metal metallogenesis of the Lengjiaxi Group. Therefore, we hypothesize that apatite in granitic rare-metal deposits within metasedimentary-magmatic-pegmatite systems might be employed as a viable proxy to explore fluid exsolution and hydrothermal alteration signature concerning its textures and geochemical fingerprints.\u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7038699\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"42 19","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139598017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kai Wang, Wenjiao Xiao, Q. Mao, He Yang, Wenhua Ji, Nijiati Abuduxun, Miao Sang, Zhihua Wang, Yanguang Li
Subduction processes of the Eastern Tianshan are crucial to understand the mechanism of the orogenic evolution of the southern Altaids. To identify whether the tectonic setting of the Late Carboniferous or later was continuous subduction, we present a systematic study on Late Carboniferous volcanic and intrusive rocks exposed continuously in time and space in the Weiya area, which were mainly derived from crustal materials with involvement of mantle-derived materials in a subduction-related setting. Our newly discovered 319 Ma A-type granites imply an extensional environment; 306 Ma diorites were derived from thickened crust. Combined with published data, we propose that rollback of the southward subducted North Tianshan oceanic plate induced subduction retreating and tectonic extension in the Yamansu-Central Tianshan arc from 324 Ma to 318 Ma. It was followed by advancing subduction from 315 Ma to 301 Ma, during which the crust of the arc was thickened, and much more crustal materials were involved in subduction-related magmatism. In the Early Permian, the arc was in an extensional environment followed by a change in the movement direction of the subducting plate, rather than in a post-orogenic setting. The final closure of the North Tianshan Ocean was likely completed in the Middle Triassic. Thematic collection: This article is part of the Processes of Pangea construction collection available at: https://www.lyellcollection.org/topic/collections/processes-of-pangea-construction Supplementary material: https://doi.org/10.6084/m9.figshare.c.7038686
东天山的俯冲过程对于了解阿尔泰南部造山演化机制至关重要。为了确定晚石炭世或更晚的构造环境是否为连续俯冲，我们对威亚地区在时间和空间上连续出露的晚石炭世火山岩和侵入岩进行了系统研究，这些岩石主要来源于地壳物质，地幔物质参与了与俯冲相关的环境。我们新发现的319 Ma A型花岗岩暗示了一种伸展环境；306 Ma闪长岩则来源于增厚的地壳。结合已发表的数据，我们认为，从 324 Ma 到 318 Ma，向南俯冲的北天山大洋板块的后退诱发了山海关-中天山弧的俯冲后退和构造延伸。随后，在315Ma至301Ma期间，天山弧地壳增厚，更多的地壳物质参与了与俯冲有关的岩浆活动。在早二叠世，弧处于俯冲板块运动方向改变后的伸展环境中，而非后成因环境中。北天山洋的最终封闭可能在中三叠世完成。 专题文集：本文是 "泛大陆构造过程"（Processes of Pangea construction）专题集的一部分，可从以下网址获取：https://www.lyellcollection.org/topic/collections/processes-of-pangea-construction 补充材料：https://doi.org/10.6084/m9.figshare.c.7038686
{"title":"Retreat and advance subduction processes in the Yamansu-Central Tianshan arc (NW China): insights into the long-lasting accretionary orogenesis and final closure of the Paleo-Asian Ocean in the southern Altaids","authors":"Kai Wang, Wenjiao Xiao, Q. Mao, He Yang, Wenhua Ji, Nijiati Abuduxun, Miao Sang, Zhihua Wang, Yanguang Li","doi":"10.1144/jgs2022-184","DOIUrl":"https://doi.org/10.1144/jgs2022-184","url":null,"abstract":"Subduction processes of the Eastern Tianshan are crucial to understand the mechanism of the orogenic evolution of the southern Altaids. To identify whether the tectonic setting of the Late Carboniferous or later was continuous subduction, we present a systematic study on Late Carboniferous volcanic and intrusive rocks exposed continuously in time and space in the Weiya area, which were mainly derived from crustal materials with involvement of mantle-derived materials in a subduction-related setting. Our newly discovered 319 Ma A-type granites imply an extensional environment; 306 Ma diorites were derived from thickened crust. Combined with published data, we propose that rollback of the southward subducted North Tianshan oceanic plate induced subduction retreating and tectonic extension in the Yamansu-Central Tianshan arc from 324 Ma to 318 Ma. It was followed by advancing subduction from 315 Ma to 301 Ma, during which the crust of the arc was thickened, and much more crustal materials were involved in subduction-related magmatism. In the Early Permian, the arc was in an extensional environment followed by a change in the movement direction of the subducting plate, rather than in a post-orogenic setting. The final closure of the North Tianshan Ocean was likely completed in the Middle Triassic.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Processes of Pangea construction collection available at:\u0000 https://www.lyellcollection.org/topic/collections/processes-of-pangea-construction\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7038686\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"31 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139598070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Previous work has proposed climatic cooling and atmosphere-ocean oxygenation as potential triggers for the Great Ordovician Biodiversification Event, with the suggestion of better oxygenated oceans during the Middle to Late Ordovician. However, recent studies have argued for spatial and temporal heterogeneity in marine redox state on several continents. Here we investigated a black-shale succession accumulated within the Tarim Platform via a combination of geochemical proxies to address these debates. Negative shifts in bulk nitrogen isotopes and synchronous increases in excess P suggest moderate-high marine primary production coinciding with the development of bottom-water anoxia, as indicated by enrichments in highly reactive iron and modest concentrations of redox-sensitive trace metals (Mo, U). Moreover, the occurrence of black shale correlates well with equivalent successions formed in deep-water marginal basins along several continents, including South China, North China, Laurentia and Baltica. This may suggest an expansion of marine anoxia in low-latitude zones of the late Darriwilian to early Sandbian oceans, probably as a result of enhanced upwelling in sync with climatic cooling. The extent and ultimate cause of marine anoxia requires further quantifying constraints at a global scale, which will enable potential links between global oceanic redox conditions and concurrent biotic changes to be evaluated in more detail. Thematic collection: This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at: https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system Supplementary material: https://doi.org/10.6084/m9.figshare.c.7036552
{"title":"Marine eutrophication within the Tarim Platform in sync with Middle to Late Ordovician climatic cooling","authors":"Junpeng Zhang, Wenjie Li, Xiang Fang, Xuejin Wu, Chao Li, Yuandong Zhang","doi":"10.1144/jgs2023-078","DOIUrl":"https://doi.org/10.1144/jgs2023-078","url":null,"abstract":"Previous work has proposed climatic cooling and atmosphere-ocean oxygenation as potential triggers for the Great Ordovician Biodiversification Event, with the suggestion of better oxygenated oceans during the Middle to Late Ordovician. However, recent studies have argued for spatial and temporal heterogeneity in marine redox state on several continents. Here we investigated a black-shale succession accumulated within the Tarim Platform via a combination of geochemical proxies to address these debates. Negative shifts in bulk nitrogen isotopes and synchronous increases in excess P suggest moderate-high marine primary production coinciding with the development of bottom-water anoxia, as indicated by enrichments in highly reactive iron and modest concentrations of redox-sensitive trace metals (Mo, U). Moreover, the occurrence of black shale correlates well with equivalent successions formed in deep-water marginal basins along several continents, including South China, North China, Laurentia and Baltica. This may suggest an expansion of marine anoxia in low-latitude zones of the late Darriwilian to early Sandbian oceans, probably as a result of enhanced upwelling in sync with climatic cooling. The extent and ultimate cause of marine anoxia requires further quantifying constraints at a global scale, which will enable potential links between global oceanic redox conditions and concurrent biotic changes to be evaluated in more detail.\u0000 \u0000 Thematic collection:\u0000 This article is part of the Chemical Evolution of the Mid-Paleozoic Earth System and Biotic Response collection available at:\u0000 https://www.lyellcollection.org/topic/collections/chemical-evolution-of-the-mid-paleozoic-earth-system\u0000 \u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7036552\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"18 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139602838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Whether the North China Block (NCB) remained extension from its cratonization to mid-Paleozoic is questionable. Here, we conducted a synthesis of zircon U-Pb data of Statherian–Ordovician sandstones to make a historical review of provenance changes in the western NCB through time. In contrast to typical NCB basement sources characterized by ca. 2.7–1.8 Ga ages with spectral peaks at ca. 2.5 and 1.9 Ga during much of ca. 1.8–0.45 Ga, Ediacaran to Cambrian Stage 3 succussions contain abundant zircons with Meso- to Neoproterozoic ages. The exotic provenance, further verified by southeastward paleo-flow, implies sources from the western Bainaimiao arc terrane (BAT), where basement rocks with suitable ages exist. Hence, the BAT should evolve at the NCB margin before ca. 0.56 Ga, but after rifting of the NCB (until ca. 773 Ma). This event led to a craton-wide stratigraphic break intervening Mesoproterozoic–Ediacaran. Presence of 521–515 Ma detrital zircons in the Cambrian Stage 3 strata indicates subduction onset of the Paleo-Asian Ocean before ca. 515 Ma, coincident with the Precambrian-Cambrian boundary paraconformity. A sequence of depositional shifts triggered by tectonic activities of the BAT unveil a complicated plate re-organization history of the northern NCB, contesting the NCB remained passive from Statherian. Supplementary material: https://doi.org/10.6084/m9.figshare.c.7040743
{"title":"Revisiting Ediacaran to early Cambrian depositional history of the western North China: Did it remain passive until mid-Paleozoic?","authors":"Jiaopeng Sun, Yunpeng Dong, Qiang Chen, Yao Ma","doi":"10.1144/jgs2023-150","DOIUrl":"https://doi.org/10.1144/jgs2023-150","url":null,"abstract":"Whether the North China Block (NCB) remained extension from its cratonization to mid-Paleozoic is questionable. Here, we conducted a synthesis of zircon U-Pb data of Statherian–Ordovician sandstones to make a historical review of provenance changes in the western NCB through time. In contrast to typical NCB basement sources characterized by ca. 2.7–1.8 Ga ages with spectral peaks at ca. 2.5 and 1.9 Ga during much of ca. 1.8–0.45 Ga, Ediacaran to Cambrian Stage 3 succussions contain abundant zircons with Meso- to Neoproterozoic ages. The exotic provenance, further verified by southeastward paleo-flow, implies sources from the western Bainaimiao arc terrane (BAT), where basement rocks with suitable ages exist. Hence, the BAT should evolve at the NCB margin before ca. 0.56 Ga, but after rifting of the NCB (until ca. 773 Ma). This event led to a craton-wide stratigraphic break intervening Mesoproterozoic–Ediacaran. Presence of 521–515 Ma detrital zircons in the Cambrian Stage 3 strata indicates subduction onset of the Paleo-Asian Ocean before ca. 515 Ma, coincident with the Precambrian-Cambrian boundary paraconformity. A sequence of depositional shifts triggered by tectonic activities of the BAT unveil a complicated plate re-organization history of the northern NCB, contesting the NCB remained passive from Statherian.\u0000 \u0000 Supplementary material:\u0000 https://doi.org/10.6084/m9.figshare.c.7040743\u0000","PeriodicalId":507891,"journal":{"name":"Journal of the Geological Society","volume":"42 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139599297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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