Pub Date : 2022-03-07eCollection Date: 2022-01-01DOI: 10.1093/schizbullopen/sgac024
Gangrui Hei, Robert C Smith, Ranran Li, Jianjun Ou, Xueqing Song, Yingjun Zheng, Yiqun He, Jen Arriaza, Jed W Fahey, Brian Cornblatt, Dongyu Kang, Ye Yang, Jing Huang, Xiaoyi Wang, Kristin Cadenhead, Mimei Zhang, John M Davis, Jingping Zhao, Hua Jin, Renrong Wu
Objective: Cognitive symptoms are associated with significant dysfunction in schizophrenia. Oxidative stress and inflammation involving histone deacetylase (HDAC) have been implicated in the pathophysiology of schizophrenia. Sulforaphane has antioxidant properties and is an HDAC inhibitor. The objective of this study was to determine the efficacy of sulforaphane on cognition dysfunction for patients with schizophrenia.
Methods: This double-blind randomized 22-week trial of patients with first-episode schizophrenia was conducted in four psychiatric institutions in China. Patients were randomized to three groups (two doses of sulforaphane vs. placebo) and symptomatic and cognitive assessments were completed at multiple times. The primary outcome measure was change in the MATRICS Composite score. The secondary outcomes were change in MATRICS Domain scores, PANSS Total Scores and change in side-effects.
Results: A total of 172 patients were randomized and 151 patients had at least one follow up evaluation. There were no significant effects of sulforaphane, on the primary outcome, MATRICS overall composite score. However, on secondary outcomes, sulforaphane did significantly improve performance scores on MATRICS battery Domains of spatial working memory (F = 5.68, P = 0.004), reasoning-problem solving (F = 2.82, P = 0.063), and verbal learning (F = 3.56, P = 0.031). There were no effects on PANSS symptom scores. Sulforaphane was well tolerated.
Conclusion: Although the primary outcome was not significant, improvement in three domains of the MATRICS battery, suggests a positive cognitive effect on some cognitive functions, which warrants further clinical trials to further assess whether sulforaphane may be a useful adjunct for treating some types of cognitive deficits in schizophrenia.
{"title":"Sulforaphane Effects on Cognition and Symptoms in First and Early Episode Schizophrenia: A Randomized Double-Blind Trial.","authors":"Gangrui Hei, Robert C Smith, Ranran Li, Jianjun Ou, Xueqing Song, Yingjun Zheng, Yiqun He, Jen Arriaza, Jed W Fahey, Brian Cornblatt, Dongyu Kang, Ye Yang, Jing Huang, Xiaoyi Wang, Kristin Cadenhead, Mimei Zhang, John M Davis, Jingping Zhao, Hua Jin, Renrong Wu","doi":"10.1093/schizbullopen/sgac024","DOIUrl":"10.1093/schizbullopen/sgac024","url":null,"abstract":"<p><strong>Objective: </strong>Cognitive symptoms are associated with significant dysfunction in schizophrenia. Oxidative stress and inflammation involving histone deacetylase (HDAC) have been implicated in the pathophysiology of schizophrenia. Sulforaphane has antioxidant properties and is an HDAC inhibitor. The objective of this study was to determine the efficacy of sulforaphane on cognition dysfunction for patients with schizophrenia.</p><p><strong>Methods: </strong>This double-blind randomized 22-week trial of patients with first-episode schizophrenia was conducted in four psychiatric institutions in China. Patients were randomized to three groups (two doses of sulforaphane vs. placebo) and symptomatic and cognitive assessments were completed at multiple times. The primary outcome measure was change in the MATRICS Composite score. The secondary outcomes were change in MATRICS Domain scores, PANSS Total Scores and change in side-effects.</p><p><strong>Results: </strong>A total of 172 patients were randomized and 151 patients had at least one follow up evaluation. There were no significant effects of sulforaphane, on the primary outcome, MATRICS overall composite score. However, on secondary outcomes, sulforaphane did significantly improve performance scores on MATRICS battery Domains of spatial working memory (<i>F</i> = 5.68, <i>P</i> = 0.004), reasoning-problem solving (<i>F</i> = 2.82, <i>P</i> = 0.063), and verbal learning (<i>F</i> = 3.56, <i>P</i> = 0.031). There were no effects on PANSS symptom scores. Sulforaphane was well tolerated.</p><p><strong>Conclusion: </strong>Although the primary outcome was not significant, improvement in three domains of the MATRICS battery, suggests a positive cognitive effect on some cognitive functions, which warrants further clinical trials to further assess whether sulforaphane may be a useful adjunct for treating some types of cognitive deficits in schizophrenia.</p>","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"1 1","pages":"sgac024"},"PeriodicalIF":0.0,"publicationDate":"2022-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11205988/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90928203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N. Planavsky, M. Fakhraee, E. Bolton, C. Reinhard, T. Isson, Shuang Zhang, Benjamin J. W. Mills
The carbonate carbon isotope record has been traditionally interpreted as evidence of stability in the globally integrated ratio of organic to total carbon burial from Earth's surface environments over the past ∼3.8 billion years, but recent work has begun to question this conclusion. Herein, we use a reactive-transport modeling approach to track organic carbon oxidation at varying atmospheric oxygen levels and use that information to provide a rough estimate of net primary production through time. Our results support the emerging view that there was extensive variability in the fraction of carbon buried as organic matter (fb,org) throughout Earth's history. We strengthen the case that the carbonate carbon isotope record has been characterized by a relatively constant baseline value over time due to a fundamental mechanistic link between atmospheric O2 levels and the carbon isotope composition of net inputs to the ocean-atmosphere system. Further, using estimates of the organic carbon burial flux (Fb,org) and the burial efficiency of the carbon pump from our marine reactive-transport modeling, we also support previous work suggesting extensive fluctuation in marine net primary production over time.
{"title":"On carbon burial and net primary production through Earth's history","authors":"N. Planavsky, M. Fakhraee, E. Bolton, C. Reinhard, T. Isson, Shuang Zhang, Benjamin J. W. Mills","doi":"10.2475/03.2022.01","DOIUrl":"https://doi.org/10.2475/03.2022.01","url":null,"abstract":"The carbonate carbon isotope record has been traditionally interpreted as evidence of stability in the globally integrated ratio of organic to total carbon burial from Earth's surface environments over the past ∼3.8 billion years, but recent work has begun to question this conclusion. Herein, we use a reactive-transport modeling approach to track organic carbon oxidation at varying atmospheric oxygen levels and use that information to provide a rough estimate of net primary production through time. Our results support the emerging view that there was extensive variability in the fraction of carbon buried as organic matter (fb,org) throughout Earth's history. We strengthen the case that the carbonate carbon isotope record has been characterized by a relatively constant baseline value over time due to a fundamental mechanistic link between atmospheric O2 levels and the carbon isotope composition of net inputs to the ocean-atmosphere system. Further, using estimates of the organic carbon burial flux (Fb,org) and the burial efficiency of the carbon pump from our marine reactive-transport modeling, we also support previous work suggesting extensive fluctuation in marine net primary production over time.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"413 - 460"},"PeriodicalIF":2.9,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43446224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Wamsutta and Nineteenmile Brook Diorites, two small plutons located in the White Mountains of New Hampshire, have bearing on the tectonic setting of magmatism between 410 and 407 Ma in this portion of the northern Appalachians. The unmetamorphosed, undated Nineteenmile Brook pluton has arc basalt affinities, produced in the same arc as the mafic magmas that were mingled with the ∼410 Ma Meredeth Porphyric Granite of central New Hampshire. These volcanic arc magmas from a westerly dipping subduction zone contributed both heat and mass to the petrogenesis of the New Hampshire Plutonic Suite (NHPS), producing the high temperature melts of the Kinsman Granodiorite of the NHPS. These peraluminous NHPS magmas were emplaced during collision of Avalonia with Laurentia, forming the bases of Acadian thrust sheets. The ∼408 Ma Wamsutta Diorite has appinite-like textures and chemically is a low SiO2 adakite, with Sr/Y ratios of ∼ 400 and (La/Yb)N between 80 and 130. These magmas were generated after flat slab, subduction erosion mixed basaltic rocks into the mantle wedge and partially melted the mafic rocks in the garnet stability field. The melts interacted with the surrounding peridotite to attain the low SiO2 adakite characteristics. At this same time, the ∼407 Ma Exeter Diorite and other arc plutons were emplaced in the Merrimack belt of southeastern New Hampshire. By 400 Ma, continued westerly dipping subduction provided mafic magma underplating to partially melt lower crustal amphibolites, generating the Spaulding Tonalite. Subsequently, lower crustal delamination and asthenospheric upwelling provided the heat source that produced a younger, post-tectonic suite of magmas between 390 and 370 Ma that, while having arc signatures because of the heritage of their crustal source rocks, are not arc magmas because subduction is thought to have ceased by this time. These plutons include the mafic rocks of the Northeast Kingdom of Vermont and the Mooselookmeguntic Igneous Complex of NH and ME. This same heat source may have contributed to melting lower to midcrustal metasediments to produce the widespread peraluminous Concord Granite of Vermont, New Hampshire, and western Maine.
Wamsutta和19mile Brook闪长岩是位于新罕布什尔州白山的两个小型深成岩体，与阿巴拉契亚山脉北部这一地区410至407 Ma之间的岩浆活动的构造背景有关。未变质、未注明日期的十九英里溪深成岩体具有弧玄武岩亲和力，与新罕布什尔州中部约410 Ma Meredeth斑岩花岗岩混合的镁铁质岩浆在同一弧中产生。这些来自向西倾斜俯冲带的火山弧岩浆为新罕布什尔Plutonic Suite（NHPS）的岩石成因提供了热量和质量，产生了NHPS的Kinsman Granodiorite的高温熔体。这些超发光的NHPS岩浆是在阿瓦隆尼亚与劳伦蒂亚碰撞期间侵位的，形成了阿卡迪亚逆冲片的基底。～408 Ma Wamsutta闪长岩具有类似阿斑岩的结构，化学性质为低SiO2埃达克岩，Sr/Y比为～400，（La/Yb）N在80至130之间。这些岩浆是在平板、俯冲侵蚀将玄武岩混合到地幔楔中并使石榴石稳定区的镁铁质岩石部分熔融后产生的。熔体与周围的橄榄岩相互作用，以获得低SiO2埃达克岩特征。与此同时，约407 Ma Exeter闪长岩和其他弧形深成岩体被侵位在新罕布什尔州东南部的梅里马克带。到400 Ma，持续的西向俯冲提供了镁铁质岩浆底侵作用，使下地壳角闪岩部分熔融，生成斯波丁方钠石。随后，下地壳分层和软流圈上升流提供了热源，在390至370 Ma之间产生了一套更年轻的后构造岩浆，这些岩浆虽然由于其地壳源岩的继承而具有弧形特征，但不是弧形岩浆，因为俯冲被认为在此时已经停止。这些深成岩体包括佛蒙特州东北王国的镁铁质岩石以及NH和ME的Mooselookmeguntic火成岩杂岩。同样的热源可能有助于融化地壳下部至中部的变质沉积物，从而产生佛蒙特州、新罕布什尔州和缅因州西部广泛分布的过铝质康科德花岗岩。
{"title":"The petrogenesis and tectonic setting of the New Hampshire Plutonic Suite: Towards a more comprehensive model for the magmatism of the Acadian Orogeny","authors":"M. Dorais","doi":"10.2475/03.2022.03","DOIUrl":"https://doi.org/10.2475/03.2022.03","url":null,"abstract":"The Wamsutta and Nineteenmile Brook Diorites, two small plutons located in the White Mountains of New Hampshire, have bearing on the tectonic setting of magmatism between 410 and 407 Ma in this portion of the northern Appalachians. The unmetamorphosed, undated Nineteenmile Brook pluton has arc basalt affinities, produced in the same arc as the mafic magmas that were mingled with the ∼410 Ma Meredeth Porphyric Granite of central New Hampshire. These volcanic arc magmas from a westerly dipping subduction zone contributed both heat and mass to the petrogenesis of the New Hampshire Plutonic Suite (NHPS), producing the high temperature melts of the Kinsman Granodiorite of the NHPS. These peraluminous NHPS magmas were emplaced during collision of Avalonia with Laurentia, forming the bases of Acadian thrust sheets. The ∼408 Ma Wamsutta Diorite has appinite-like textures and chemically is a low SiO2 adakite, with Sr/Y ratios of ∼ 400 and (La/Yb)N between 80 and 130. These magmas were generated after flat slab, subduction erosion mixed basaltic rocks into the mantle wedge and partially melted the mafic rocks in the garnet stability field. The melts interacted with the surrounding peridotite to attain the low SiO2 adakite characteristics. At this same time, the ∼407 Ma Exeter Diorite and other arc plutons were emplaced in the Merrimack belt of southeastern New Hampshire. By 400 Ma, continued westerly dipping subduction provided mafic magma underplating to partially melt lower crustal amphibolites, generating the Spaulding Tonalite. Subsequently, lower crustal delamination and asthenospheric upwelling provided the heat source that produced a younger, post-tectonic suite of magmas between 390 and 370 Ma that, while having arc signatures because of the heritage of their crustal source rocks, are not arc magmas because subduction is thought to have ceased by this time. These plutons include the mafic rocks of the Northeast Kingdom of Vermont and the Mooselookmeguntic Igneous Complex of NH and ME. This same heat source may have contributed to melting lower to midcrustal metasediments to produce the widespread peraluminous Concord Granite of Vermont, New Hampshire, and western Maine.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"493 - 531"},"PeriodicalIF":2.9,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44798434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
P. Maffre, Y. Goddéris, A. Pohl, Y. Donnadieu, S. Carretier, Guillaume Le Hir
The first forests appeared on the continents during the Givetian stage of the Devonian. The fossil record shows that, by the end of the Devonian, vascular plants and forests were common and widespread in the wet lowlands. Although the impact of this major event on chemical weathering of the continents is reasonably known, the coeval change in physical erosion has never been explored. Here, we build a mathematical description of the coupled response of the physical erosion and chemical weathering on the continents, to the colonization by vascular plants over the course of the Devonian. This spatially-resolved erosion model is coupled to the GEOCLIM model to simulate the response of the global carbon and alkalinity cycles, and of climate, to the colonization phase. A set of simulations is described, assuming an increased weatherability of the continental surface, and a change in physical erosion which can be either a decrease or an increase in response to the spreading of vascular plants. We explore first the initial pre-colonization and the final post-colonization steady states of the surficial Earth system. Then, we simulate the transient states of the Earth system in response to theoretical randomized scenarios for the colonization. We find that the pathways of the colonization have a major impact on the CO2 history through the Devonian. Depending on the magnitude of the change in physical erodibility and chemical weatherability, and on the colonization scenario, atmospheric CO2 evolution may display contrasting behaviors: from a uniform CO2 decrease over the Devonian, to more complex patterns characterized first by a global warming from the end of the Givetian into the Frasnian, and then by a final cooling, in first order agreement with the proxy data for CO2 and reconstructed climate evolution.
{"title":"The complex response of continental silicate rock weathering to the colonization of the continents by vascular plants in the Devonian","authors":"P. Maffre, Y. Goddéris, A. Pohl, Y. Donnadieu, S. Carretier, Guillaume Le Hir","doi":"10.2475/03.2022.02","DOIUrl":"https://doi.org/10.2475/03.2022.02","url":null,"abstract":"The first forests appeared on the continents during the Givetian stage of the Devonian. The fossil record shows that, by the end of the Devonian, vascular plants and forests were common and widespread in the wet lowlands. Although the impact of this major event on chemical weathering of the continents is reasonably known, the coeval change in physical erosion has never been explored. Here, we build a mathematical description of the coupled response of the physical erosion and chemical weathering on the continents, to the colonization by vascular plants over the course of the Devonian. This spatially-resolved erosion model is coupled to the GEOCLIM model to simulate the response of the global carbon and alkalinity cycles, and of climate, to the colonization phase. A set of simulations is described, assuming an increased weatherability of the continental surface, and a change in physical erosion which can be either a decrease or an increase in response to the spreading of vascular plants. We explore first the initial pre-colonization and the final post-colonization steady states of the surficial Earth system. Then, we simulate the transient states of the Earth system in response to theoretical randomized scenarios for the colonization. We find that the pathways of the colonization have a major impact on the CO2 history through the Devonian. Depending on the magnitude of the change in physical erodibility and chemical weatherability, and on the colonization scenario, atmospheric CO2 evolution may display contrasting behaviors: from a uniform CO2 decrease over the Devonian, to more complex patterns characterized first by a global warming from the end of the Givetian into the Frasnian, and then by a final cooling, in first order agreement with the proxy data for CO2 and reconstructed climate evolution.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"461 - 492"},"PeriodicalIF":2.9,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47564169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Kukla, J. Rugenstein, E. Driscoll, D. Ibarra, C. Chamberlain
In the last two decades, analytical advances and a growing interest in relevant research questions has brought a rapid increase in the amount of stable isotope data used for reconstructing terrestrial paleoclimates and environments. As the spatial and temporal resolution of proxy data continues to improve, the quantitative interpretation of these data is becoming increasingly common. These advances in data resolution and theory bring opportunities for multi-proxy comparisons, synthesis and modeling of large datasets, integration with paleoecological datasets, improved climate model benchmarking, and more. Here, in an effort to support these growing avenues of research, we present The PATCH Lab (Paleo-Analysis of Terrestrial Climate and Hydrology)—an online portal to discover, download, and quantitatively analyze deep time (>1 Ma) terrestrial stable isotope data. The PATCH Lab portal hosts a new database that currently includes 27009 stable isotope measurements from 211 publications spanning multiple terrestrial proxies, and quantitative models for interpreting water isotope and soil carbonate data. Data query, download, and modeling results are organized into user-friendly graphical interfaces that export datasets as .csv files. New data can be easily submitted to the PATCH Lab curators through the portal by completing a data submission template. The PATCH Lab, with the help of community engagement, serves as a resource for archiving terrestrial stable isotope data, building paleo “isoscapes”, and increasing accessibility to quantitative methods of investigating terrestrial stable isotopes in paleoclimate.
{"title":"The PATCH Lab v1.0: A database and workspace for Cenozoic terrestrial paleoclimate and environment reconstruction","authors":"T. Kukla, J. Rugenstein, E. Driscoll, D. Ibarra, C. Chamberlain","doi":"10.31223/x5pk9w","DOIUrl":"https://doi.org/10.31223/x5pk9w","url":null,"abstract":"In the last two decades, analytical advances and a growing interest in relevant research questions has brought a rapid increase in the amount of stable isotope data used for reconstructing terrestrial paleoclimates and environments. As the spatial and temporal resolution of proxy data continues to improve, the quantitative interpretation of these data is becoming increasingly common. These advances in data resolution and theory bring opportunities for multi-proxy comparisons, synthesis and modeling of large datasets, integration with paleoecological datasets, improved climate model benchmarking, and more. Here, in an effort to support these growing avenues of research, we present The PATCH Lab (Paleo-Analysis of Terrestrial Climate and Hydrology)—an online portal to discover, download, and quantitatively analyze deep time (>1 Ma) terrestrial stable isotope data. The PATCH Lab portal hosts a new database that currently includes 27009 stable isotope measurements from 211 publications spanning multiple terrestrial proxies, and quantitative models for interpreting water isotope and soil carbonate data. Data query, download, and modeling results are organized into user-friendly graphical interfaces that export datasets as .csv files. New data can be easily submitted to the PATCH Lab curators through the portal by completing a data submission template. The PATCH Lab, with the help of community engagement, serves as a resource for archiving terrestrial stable isotope data, building paleo “isoscapes”, and increasing accessibility to quantitative methods of investigating terrestrial stable isotopes in paleoclimate.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"1124 - 1158"},"PeriodicalIF":2.9,"publicationDate":"2022-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46613815","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhen Wang, Yuruo Shi, Tianshui Yang, J. Anderson, Chenyang Hou, Yuelan Kang, Wenxiao Peng, Yiming Ma, W. Bian
In this contribution, we report new U-Pb SHRIMP zircon ages and geochemical data for volcanic rocks from the Dianzhong Formation. The unit represents the lower part of the Linzizong volcanic succession located in the Shiquanhe area, western part of the Gangdese belt. Zircon U-Pb dating of three trachytes yields 206Pb/238U crystallization ages of 71.5±0.6 Ma, 70.8±1.0 Ma and 68.9±1.0 Ma. Whole rock major and trace element analyses indicate a main trend of calc-alkalic to high-potassic calc-alkalic, as well as an enrichment in large ion lithophile elements (LILEs), depletion in high field strength elements (HFSEs), with negative Nb, Ta and Ti anomalies. In addition, these volcanic rocks are enriched in LREE and depleted in HREE without a clear Eu anomaly. These geochemical features are similar to those of active continental margin volcanic rocks. In combination with previously published zircon U-Pb ages and geochemical data of the Dianzhong Formation, we suggest that the Linzizong volcanism started as early as the late Cretaceous (∼71 Ma) and the volcanic rocks of the Dianzhong Formation in the Shiquanhe area are the product of rollback of the Neo-Tethyan oceanic plate.
{"title":"Constraints on the rollback of the Neo-Tethyan oceanic plate: Geochronology and geochemistry of volcanic rocks from the Dianzhong Formation, western Gangdese belt (Tibetan Plateau)","authors":"Zhen Wang, Yuruo Shi, Tianshui Yang, J. Anderson, Chenyang Hou, Yuelan Kang, Wenxiao Peng, Yiming Ma, W. Bian","doi":"10.2475/02.2022.10","DOIUrl":"https://doi.org/10.2475/02.2022.10","url":null,"abstract":"In this contribution, we report new U-Pb SHRIMP zircon ages and geochemical data for volcanic rocks from the Dianzhong Formation. The unit represents the lower part of the Linzizong volcanic succession located in the Shiquanhe area, western part of the Gangdese belt. Zircon U-Pb dating of three trachytes yields 206Pb/238U crystallization ages of 71.5±0.6 Ma, 70.8±1.0 Ma and 68.9±1.0 Ma. Whole rock major and trace element analyses indicate a main trend of calc-alkalic to high-potassic calc-alkalic, as well as an enrichment in large ion lithophile elements (LILEs), depletion in high field strength elements (HFSEs), with negative Nb, Ta and Ti anomalies. In addition, these volcanic rocks are enriched in LREE and depleted in HREE without a clear Eu anomaly. These geochemical features are similar to those of active continental margin volcanic rocks. In combination with previously published zircon U-Pb ages and geochemical data of the Dianzhong Formation, we suggest that the Linzizong volcanism started as early as the late Cretaceous (∼71 Ma) and the volcanic rocks of the Dianzhong Formation in the Shiquanhe area are the product of rollback of the Neo-Tethyan oceanic plate.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"396 - 411"},"PeriodicalIF":2.9,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45886308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Heubeck, N. Drabon, G. Byerly, Isabelle Leisgang, U. Linnemann, D. Lowe, R. Mertz‐Kraus, Alejandra Gonzalez-Pinzón, T. Thomsen, A. Zeh, Y. Rojas‐Agramonte, A. Kröner
Sandstones of the 3.22 Ga Archean Moodies Group represent one of the world's oldest quartz-rich sedimentary sequences. The provenance of this unit is unresolved because its quartz and common microcline can be sourced both from either now eroded or covered granitoid plutons outside the Barberton Greenstone Belt (BGB) or, alternatively and perhaps more controversially, (rhyo-)dacitic (sub-)volcanic rocks within the BGB. We compiled 31 detrital zircon data sets (n = 2588) from sandstones, reworked tuffs and conglomerate of the Moodies Group in order to constrain its age and provenance. After selection using quality criteria, the remaining zircons (n = 1621) in nearly all samples show a distribution corresponding to the four known major pulses of felsic magmatism in the BGB: 1) the ca. 3550 to 3530 Ma Theespruit and Sandspruit Formations at the base of the Onverwacht Group; 2) the ca. 3440 to 3410 Ma rhyo-dacites of the upper Hooggenoeg Formation, Onverwacht Group; 3) the ca. 3300 to 3280 Ma thin felsic tuffs in the Mendon Formation; and 4) the ca. 3260 to 3215 Ma felsic volcanic and shallow intrusive rocks of the Auber Villiers, Bien Venue and Schoongezicht Formations of the upper Fig Tree Group and the Moodies Group as well as their co-magmatic plutonic counterparts. Almost all data sets also contain near-concordant younger zircons as young as 2820 Ma, which can be attributed to one of six tectonic or magmatic events affecting the young Kaapvaal Craton in post-BGB time, causing the partial or complete resetting of the U-Pb system in some grains. The youngest (near-)concordant zircon clusters yield ages of ca. 3220 Ma in most locations, and the youngest discordant group of zircons from a reworked tuff near the top of the Moodies Group at 3212 ± 13 Ma agrees well with previous estimates of the maximum depositional age. With very few exceptions, the oldest zircons (ca. 3564 Ma) are only slightly older than the oldest rocks in the BGB stratigraphy (ca. 3550 Ma). Subtle regional and stratigraphic differences in age spectra may indicate localized or nearby sediment sources within a synorogenic setting. Preliminary age spectra along vertical stratigraphic profiles show little systematic variation, possibly indicating that intrabasinal recycling was dominant over considerable time periods of the basin's evolution. Extra-basinal plutonic sources of similar age and composition as the intra-BGB sources appear to be required to provide quartz and some feldspar to Moodies Group sandstones, although zircon age spectra, limited zircon Hf isotope data, sandstone petrography, facies analysis, and the high variability in Moodies conglomerate clast composition are consistent with uplift, deformation and erosion of several intra-BGB sources, but in particular from the region of the Onverwacht Anticline. Zircon populations, conglomerate clasts, and sandstone composition show no evidence that high-grade metamorphic rocks from the adjacent Ancient Gneiss Complex (AGC) co
3.22 Ga太古宙穆迪群的砂岩代表了世界上最古老的富含石英的沉积序列之一。该单元的来源尚未确定，因为其石英和常见的微斜长石既可以来源于Barberton Greenstone Belt（BGB）外现已被侵蚀或覆盖的花岗质深成岩体，也可以来源于BGB内的（rhyo-）英安质（亚）火山岩。我们从穆迪组的砂岩、改造凝灰岩和砾岩中汇编了31个碎屑锆石数据集（n=2588），以限制其年龄和物源。在使用质量标准进行选择后，几乎所有样品中的剩余锆石（n=1621）显示出与BGB中长英质岩浆作用的四个已知主脉冲相对应的分布：1）Onverwacht群底部的约3550至3530 Ma Theespruit和Sandspruit组；2） Onverwacht群Hooggenoeg组上部的约3440至3410 Ma rhyo英安岩；3） Mendon组中约3300至3280 Ma的薄长英质凝灰岩；和4）上部无花果树群和穆迪群的Auber Villiers、Bien Venue和Schongezicht组的约3260至3215 Ma长英质火山岩和浅侵入岩，以及它们的同岩浆深成岩对应物。几乎所有的数据集都包含年龄为2820 Ma的近乎一致的年轻锆石，这可归因于后BGB时期影响年轻Kaapvaal火山口的六个构造或岩浆事件之一，导致一些颗粒中的U-Pb系统部分或完全重置。最年轻（接近）的一致锆石群在大多数位置产生的年龄约为3220 Ma，最年轻的不一致锆石群来自穆迪群顶部附近的改造凝灰岩，在3212±13 Ma，与之前对最大沉积年龄的估计非常一致。除了极少数例外，最古老的锆石（约3564 Ma）仅比BGB地层中最古老的岩石（约3550 Ma）略老。年龄谱中细微的区域和地层差异可能表明同造山带环境中的局部或附近沉积物来源。沿垂直地层剖面的初步年龄谱显示出很少的系统变化，这可能表明在盆地演化的相当长的一段时间内，盆地内的再循环占主导地位。尽管锆石年龄谱、有限的锆石Hf同位素数据、砂岩岩石学、相分析以及穆迪砾岩碎屑组成的高度变异性与隆起一致，但似乎需要与BGB内部来源具有相似年龄和成分的盆地外深成岩体来源来为穆迪群砂岩提供石英和一些长石，几个BGB内部源的变形和侵蚀，特别是来自Onverwacht背斜区域的。锆石种群、砾岩碎屑和砂岩成分没有证据表明邻近古片麻岩杂岩（AGC）的高级变质岩对穆迪群有重大贡献。
{"title":"Detrital zircon provenance of the Archean Moodies Group, Barberton Greenstone Belt, South Africa and Eswatini","authors":"C. Heubeck, N. Drabon, G. Byerly, Isabelle Leisgang, U. Linnemann, D. Lowe, R. Mertz‐Kraus, Alejandra Gonzalez-Pinzón, T. Thomsen, A. Zeh, Y. Rojas‐Agramonte, A. Kröner","doi":"10.2475/02.2022.01","DOIUrl":"https://doi.org/10.2475/02.2022.01","url":null,"abstract":"Sandstones of the 3.22 Ga Archean Moodies Group represent one of the world's oldest quartz-rich sedimentary sequences. The provenance of this unit is unresolved because its quartz and common microcline can be sourced both from either now eroded or covered granitoid plutons outside the Barberton Greenstone Belt (BGB) or, alternatively and perhaps more controversially, (rhyo-)dacitic (sub-)volcanic rocks within the BGB. We compiled 31 detrital zircon data sets (n = 2588) from sandstones, reworked tuffs and conglomerate of the Moodies Group in order to constrain its age and provenance. After selection using quality criteria, the remaining zircons (n = 1621) in nearly all samples show a distribution corresponding to the four known major pulses of felsic magmatism in the BGB: 1) the ca. 3550 to 3530 Ma Theespruit and Sandspruit Formations at the base of the Onverwacht Group; 2) the ca. 3440 to 3410 Ma rhyo-dacites of the upper Hooggenoeg Formation, Onverwacht Group; 3) the ca. 3300 to 3280 Ma thin felsic tuffs in the Mendon Formation; and 4) the ca. 3260 to 3215 Ma felsic volcanic and shallow intrusive rocks of the Auber Villiers, Bien Venue and Schoongezicht Formations of the upper Fig Tree Group and the Moodies Group as well as their co-magmatic plutonic counterparts. Almost all data sets also contain near-concordant younger zircons as young as 2820 Ma, which can be attributed to one of six tectonic or magmatic events affecting the young Kaapvaal Craton in post-BGB time, causing the partial or complete resetting of the U-Pb system in some grains. The youngest (near-)concordant zircon clusters yield ages of ca. 3220 Ma in most locations, and the youngest discordant group of zircons from a reworked tuff near the top of the Moodies Group at 3212 ± 13 Ma agrees well with previous estimates of the maximum depositional age. With very few exceptions, the oldest zircons (ca. 3564 Ma) are only slightly older than the oldest rocks in the BGB stratigraphy (ca. 3550 Ma). Subtle regional and stratigraphic differences in age spectra may indicate localized or nearby sediment sources within a synorogenic setting. Preliminary age spectra along vertical stratigraphic profiles show little systematic variation, possibly indicating that intrabasinal recycling was dominant over considerable time periods of the basin's evolution. Extra-basinal plutonic sources of similar age and composition as the intra-BGB sources appear to be required to provide quartz and some feldspar to Moodies Group sandstones, although zircon age spectra, limited zircon Hf isotope data, sandstone petrography, facies analysis, and the high variability in Moodies conglomerate clast composition are consistent with uplift, deformation and erosion of several intra-BGB sources, but in particular from the region of the Onverwacht Anticline. Zircon populations, conglomerate clasts, and sandstone composition show no evidence that high-grade metamorphic rocks from the adjacent Ancient Gneiss Complex (AGC) co","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"65 - 107"},"PeriodicalIF":2.9,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44237442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Chen, H. Schertl, A. Cambeses, Emma Hart, Chenggui Lin, Rongke Xu, Youye Zheng
The most significant mass transfer processes at a convergent plate boundary are tectonic accretion and fluids/melts released from sites of generation to sites of accumulation. However, some crucial questions remain with regards to the source, timescale, and evolution of such anatectic processes, for example, single or multistage anatexis of deeply subducted continental crust. To better understand the processes involved in anatexis, we have quantified the timescale and nature of formation and evolution processes of multistage felsic veins within retrograde eclogite using zircon, monazite, and xenotime geochemistry and geochronology, whole-rock composition, and Sr-Nd-Hf isotope analysis from the Lüliangshan, North Qaidam orogen. The U–Pb dating of coexisting zircon, monazite, and xenotime gives three groups of ages at ca. 441 to 435, ca. 425, and ca. 413 to 409 Ma, respectively, which record at least three episodes of pulsed melts. The first stage of zircon formation is characterized by not only the absence of oscillatory zoning of different zircons in cathodoluminescence images but also some of them with flat HREE and without Eu anomalies, indicating they may form in anatectic melts under eclogite-facies conditions. The second and third phases of melts may have occurred under granulite- and amphibole-facies conditions during exhumation. Furthermore, two classes of felsic veins within the eclogite show wide variations of whole-rock composition, (87Sr/86Sr)i, εNd (t), and εHf (t) values, which demonstrate that they were derived from fluid-present dehydration partial melting of different proportions of subducted gneiss and eclogite during different periods. These findings show that melts have systematic differences in chemical and isotopic signatures resulting from lithological diversity and depth of partial melting. Thus, small-scale melts released from the source can excellently explain the variability in whole-rock composition, accessory mineral growth zoning, and prominent isotope variability in syn-collisional heterogeneous granites. An additional implication is that as these melts escape their adjacent area of formation, they migrate and mix along channelized melt pathways, resulting in melt-rock and crust-mantle interaction and the triggering of syn- and post-collisional magmatism.
{"title":"Cyclicity of multistage anatexis of deeply subducted continental crust during the North Qaidam orogeny: Tracing the source, timescale, and evolution of pulsed melts","authors":"Xin Chen, H. Schertl, A. Cambeses, Emma Hart, Chenggui Lin, Rongke Xu, Youye Zheng","doi":"10.2475/02.2022.05","DOIUrl":"https://doi.org/10.2475/02.2022.05","url":null,"abstract":"The most significant mass transfer processes at a convergent plate boundary are tectonic accretion and fluids/melts released from sites of generation to sites of accumulation. However, some crucial questions remain with regards to the source, timescale, and evolution of such anatectic processes, for example, single or multistage anatexis of deeply subducted continental crust. To better understand the processes involved in anatexis, we have quantified the timescale and nature of formation and evolution processes of multistage felsic veins within retrograde eclogite using zircon, monazite, and xenotime geochemistry and geochronology, whole-rock composition, and Sr-Nd-Hf isotope analysis from the Lüliangshan, North Qaidam orogen. The U–Pb dating of coexisting zircon, monazite, and xenotime gives three groups of ages at ca. 441 to 435, ca. 425, and ca. 413 to 409 Ma, respectively, which record at least three episodes of pulsed melts. The first stage of zircon formation is characterized by not only the absence of oscillatory zoning of different zircons in cathodoluminescence images but also some of them with flat HREE and without Eu anomalies, indicating they may form in anatectic melts under eclogite-facies conditions. The second and third phases of melts may have occurred under granulite- and amphibole-facies conditions during exhumation. Furthermore, two classes of felsic veins within the eclogite show wide variations of whole-rock composition, (87Sr/86Sr)i, εNd (t), and εHf (t) values, which demonstrate that they were derived from fluid-present dehydration partial melting of different proportions of subducted gneiss and eclogite during different periods. These findings show that melts have systematic differences in chemical and isotopic signatures resulting from lithological diversity and depth of partial melting. Thus, small-scale melts released from the source can excellently explain the variability in whole-rock composition, accessory mineral growth zoning, and prominent isotope variability in syn-collisional heterogeneous granites. An additional implication is that as these melts escape their adjacent area of formation, they migrate and mix along channelized melt pathways, resulting in melt-rock and crust-mantle interaction and the triggering of syn- and post-collisional magmatism.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"225 - 279"},"PeriodicalIF":2.9,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45762784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
X. Cui, M. Sun, Guochun Zhao, Jinlong Yao, Yunying Zhang, Yigui Han
High-grade gneisses are widespread in the Chinese segment of the Altai orogen, but their nature is not yet well-constrained with interpretations varying from Precambrian basement to Paleozoic meta-sediments. Such a controversy has hindered our understanding of the early Paleozoic geologic history of the Altai orogen. This study presents whole-rock geochemistry, zircon U-Pb and Hf isotopic data for paragneisses from the Qiongkuer Domain of the southern Chinese Altai, aiming to reveal their sedimentary and metamorphic history and shed light on the geodynamics of the Altai orogen. The paragneisses contain detrital zircons with mostly euhedral shapes, which, together with their weak HREE fractionation and Zr-Hf depletion relative to continental crust, may imply short-distance transport and low maturity of the sediments. In addition, these rocks have felsic compositions, high Rb contents and negative Eu anomalies, as well as low La/Sc and high Co/Th ratios, possibly indicating an acidic-intermediate igneous provenance. Our results show that the detrital zircons from the paragneisses are dominantly ca. 535 to 435 Ma old, some have Neoproterozoic ages, and only a few have Mesoproterozoic or Archean ages. Since the youngest detrital zircon population record an early Silurian weighted mean age of 441 Ma, and an early Devonian (411 Ma) granite intruded these paragneisses, we infer that their protoliths were deposited in the Silurian. The cumulative distribution curves of zircon age spectra of the paragneisses are comparable to those of sediments at convergent continental margins. The large spread of εHf(t) values (−9.5 to +12.9) of the predominant Paleozoic zircons also reflects possible active margin settings which contain both juvenile and reworked materials in the source. Therefore, the protoliths of the studied paragneisses were immature sediments mostly deposited at an active continental margin during the early Paleozoic and sourced mainly from proximal igneous rocks. Similar detrital zircon age spectra of early Paleozoic sequences from the Chinese Altai, Mongolia Altai, and Khovd Zone support the existence of a large accretionary wedge developed along the western margin of the Ikh-Mongol Arc system, resulting from continuous northeast-dipping oceanic subduction.
{"title":"An early Paleozoic active continental margin basin along the southern Chinese Altai: Evidence from high-grade paragneisses in the Fuyun region","authors":"X. Cui, M. Sun, Guochun Zhao, Jinlong Yao, Yunying Zhang, Yigui Han","doi":"10.2475/02.2022.04","DOIUrl":"https://doi.org/10.2475/02.2022.04","url":null,"abstract":"High-grade gneisses are widespread in the Chinese segment of the Altai orogen, but their nature is not yet well-constrained with interpretations varying from Precambrian basement to Paleozoic meta-sediments. Such a controversy has hindered our understanding of the early Paleozoic geologic history of the Altai orogen. This study presents whole-rock geochemistry, zircon U-Pb and Hf isotopic data for paragneisses from the Qiongkuer Domain of the southern Chinese Altai, aiming to reveal their sedimentary and metamorphic history and shed light on the geodynamics of the Altai orogen. The paragneisses contain detrital zircons with mostly euhedral shapes, which, together with their weak HREE fractionation and Zr-Hf depletion relative to continental crust, may imply short-distance transport and low maturity of the sediments. In addition, these rocks have felsic compositions, high Rb contents and negative Eu anomalies, as well as low La/Sc and high Co/Th ratios, possibly indicating an acidic-intermediate igneous provenance. Our results show that the detrital zircons from the paragneisses are dominantly ca. 535 to 435 Ma old, some have Neoproterozoic ages, and only a few have Mesoproterozoic or Archean ages. Since the youngest detrital zircon population record an early Silurian weighted mean age of 441 Ma, and an early Devonian (411 Ma) granite intruded these paragneisses, we infer that their protoliths were deposited in the Silurian. The cumulative distribution curves of zircon age spectra of the paragneisses are comparable to those of sediments at convergent continental margins. The large spread of εHf(t) values (−9.5 to +12.9) of the predominant Paleozoic zircons also reflects possible active margin settings which contain both juvenile and reworked materials in the source. Therefore, the protoliths of the studied paragneisses were immature sediments mostly deposited at an active continental margin during the early Paleozoic and sourced mainly from proximal igneous rocks. Similar detrital zircon age spectra of early Paleozoic sequences from the Chinese Altai, Mongolia Altai, and Khovd Zone support the existence of a large accretionary wedge developed along the western margin of the Ikh-Mongol Arc system, resulting from continuous northeast-dipping oceanic subduction.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"190 - 224"},"PeriodicalIF":2.9,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47204862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bingqing Xu, Guochun Zhao, Jinlong Yao, Peng Wang, Yanhong He, Yigui Han, H. Zhou, Bo Wang
The closure time of the Hegenshan Ocean and its suturing scenario is debated, which hinders our understanding of the architecture and tectonic evolution of the southeastern Central Asian Orogenic Belt. We present an integrated study of in-situ zircon U-Pb isotopic ages and Hf isotope compositions, whole-rock geochemistry and Sr-Nd isotopes on the less-studied Erenhot granitic pluton in central Inner Mongolia. The ca. 303 to 300 Ma Erenhot pluton is composed of monzogranites, which are high-K calc-alkaline rocks and show I-type affinities. Moreover, positive correlation between Ba and Sr, along with the notably positive Rb and Pb anomalies, negative δEu and depletion in Ba, Eu, Nb and Ti, imply crystal fractionation played an important role in the magma evolution. The pluton also shows relative enrichment in light rare earth elements and large ion lithophile elements and depletion in high field strength elements, typical features of subduction-related magma. Isotopically, predominantly positive whole-rock εNd(t) (0.9–3.8) and zircon εHf(t) (4.50–13.66) values indicate a dominant juvenile crustal source with minor older crustal contamination. Given the mostly Proterozoic model ages (1318–543 Ma) and the presence of xenocrystic zircons, we infer that the Erenhot pluton probably was formed in a continental arc setting. Combined with the available published data, it is proposed that an east-west trending continental arc developed and was accreted onto the Uliastai Continental Margin in the Carboniferous, resulting from the northward subduction of the Hegenshan Ocean. The late Carboniferous continental arc-related magmatism (ca. 303–300 Ma) at Erenhot probably witnessed the waning stage of Hegenshan oceanic lithosphere subduction beneath the Uliastai Continental Margin.
{"title":"Late carboniferous continental arc magmatism in the southeastern Central Asian Orogenic Belt: insights from the Erenhot granitic pluton, Inner Mongolia","authors":"Bingqing Xu, Guochun Zhao, Jinlong Yao, Peng Wang, Yanhong He, Yigui Han, H. Zhou, Bo Wang","doi":"10.2475/02.2022.08","DOIUrl":"https://doi.org/10.2475/02.2022.08","url":null,"abstract":"The closure time of the Hegenshan Ocean and its suturing scenario is debated, which hinders our understanding of the architecture and tectonic evolution of the southeastern Central Asian Orogenic Belt. We present an integrated study of in-situ zircon U-Pb isotopic ages and Hf isotope compositions, whole-rock geochemistry and Sr-Nd isotopes on the less-studied Erenhot granitic pluton in central Inner Mongolia. The ca. 303 to 300 Ma Erenhot pluton is composed of monzogranites, which are high-K calc-alkaline rocks and show I-type affinities. Moreover, positive correlation between Ba and Sr, along with the notably positive Rb and Pb anomalies, negative δEu and depletion in Ba, Eu, Nb and Ti, imply crystal fractionation played an important role in the magma evolution. The pluton also shows relative enrichment in light rare earth elements and large ion lithophile elements and depletion in high field strength elements, typical features of subduction-related magma. Isotopically, predominantly positive whole-rock εNd(t) (0.9–3.8) and zircon εHf(t) (4.50–13.66) values indicate a dominant juvenile crustal source with minor older crustal contamination. Given the mostly Proterozoic model ages (1318–543 Ma) and the presence of xenocrystic zircons, we infer that the Erenhot pluton probably was formed in a continental arc setting. Combined with the available published data, it is proposed that an east-west trending continental arc developed and was accreted onto the Uliastai Continental Margin in the Carboniferous, resulting from the northward subduction of the Hegenshan Ocean. The late Carboniferous continental arc-related magmatism (ca. 303–300 Ma) at Erenhot probably witnessed the waning stage of Hegenshan oceanic lithosphere subduction beneath the Uliastai Continental Margin.","PeriodicalId":7660,"journal":{"name":"American Journal of Science","volume":"322 1","pages":"351 - 379"},"PeriodicalIF":2.9,"publicationDate":"2022-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48444665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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