The Beishan orogenic zone is a key area to understand evolution of the Central Asian Orogenic Belt that is an accretionary factory well-enough preserved in the Paleozoic. In early Paleozoic, the tectonic mélange ...The Beishan orogenic zone is a key area to understand evolution of the Central Asian Orogenic Belt that is an accretionary factory well-enough preserved in the Paleozoic. In early Paleozoic, the tectonic mélange zone containing the coherent unit and mélange unit is triggered by the complicated accretionary process of the Beishan area. The early Paleozoic tectonic evolution of the Beishan orogenic zone is investigated in this study using sedimentology and stratigraphic correlations of the lowe Paleozoic deposits. From the Cambrian to the middle Ordovician, this region was characterized by geographically extensive, flat-bedded siliceous mudstone, indicating the existence of a large ocean basin. The oceanic plate entered the convergence phase in terms of the Wilson Circle during the Middle Ordovician, when numerous magmatic arcs formed along two opposite sides of the ocean. The magmatic arcs became the widest during the Silurian, suggesting that the Hongliuhe-Niujuanzi-Xichangjing Ocean(HNX;a southern branch of the Paleo Asian Ocean) was reduced to a small residual ocean in the central Beishan region by that time, and probably lasted till the Carboniferous or later by newly published data.展开更多
Objective Time-specific litho- and biofacies often holds important information about unique ancient ecosystems that no longer exist on Earth today. This report summarizes one of such time-specific facies--the 3-D net...Objective Time-specific litho- and biofacies often holds important information about unique ancient ecosystems that no longer exist on Earth today. This report summarizes one of such time-specific facies--the 3-D network structure of the Upper Ordovician Pagoda Formation in South China, as investigated by Zhan et al. （Palaeogeography, Palaeocli-matology, Palaeoecology, DOI： 10.1016/j.palaeo.2015.07.039）.展开更多
Eospirifer,the oldest known genus of the spiriferide group(Brachiopoda),first appeared on the Zhe-Gan Platform of South China paleoplate during late Katian(Late Ordovician) represented by E.praecursor.It survived the ...Eospirifer,the oldest known genus of the spiriferide group(Brachiopoda),first appeared on the Zhe-Gan Platform of South China paleoplate during late Katian(Late Ordovician) represented by E.praecursor.It survived the end-Ordovician mass extinction,and reappeared on the Upper Yangtze Platform of South China paleoplate by the end of Ordovician near the upper part of the Normalograptus persculptus Biozone.Starting from the beginning of Silurian,Eospirifer experienced some morphological innovations and expanded its geographical distribution substantially.It reached its species diversity acme and the widest geographic distribution in Wenlock(middle Silurian),with the diversity hotspots in Laurentia,Avalonia,and Baltica.Various shell size frequency curves of E.praecursor under different paleogeographic settings suggest that this pioneer species of Eospirifer,with several macroevolutionary novelties,adopted a range of life strategies to adapt to the changing environments during early spiriferide evolution.There are also some morphological macroevolutionary trends during the evolutionary history of Eospirifer from Late Ordovician to the end of Silurian,such as the ever enlarging shell sizes and the width/length ratios from late Katian to Wenlock,but decreasing apparently of both parameters from Wenlock to Pridoli.展开更多
基金funded by the National Natural Science Foundation(No.41772107)the Geological Survey Program(No.DD20190370 and No.DD20190812)of the People's Republic of Chinathe National Key Research,Development Program of China(No.2016YFC0601005)。
文摘The Beishan orogenic zone is a key area to understand evolution of the Central Asian Orogenic Belt that is an accretionary factory well-enough preserved in the Paleozoic. In early Paleozoic, the tectonic mélange zone containing the coherent unit and mélange unit is triggered by the complicated accretionary process of the Beishan area. The early Paleozoic tectonic evolution of the Beishan orogenic zone is investigated in this study using sedimentology and stratigraphic correlations of the lowe Paleozoic deposits. From the Cambrian to the middle Ordovician, this region was characterized by geographically extensive, flat-bedded siliceous mudstone, indicating the existence of a large ocean basin. The oceanic plate entered the convergence phase in terms of the Wilson Circle during the Middle Ordovician, when numerous magmatic arcs formed along two opposite sides of the ocean. The magmatic arcs became the widest during the Silurian, suggesting that the Hongliuhe-Niujuanzi-Xichangjing Ocean(HNX;a southern branch of the Paleo Asian Ocean) was reduced to a small residual ocean in the central Beishan region by that time, and probably lasted till the Carboniferous or later by newly published data.
基金supported by the National Natural Science Foundation of China(grant No.41521061, 41290260)the State Key Laboratory of Paleobiology and Stratigraphy(LPS)
文摘Objective Time-specific litho- and biofacies often holds important information about unique ancient ecosystems that no longer exist on Earth today. This report summarizes one of such time-specific facies--the 3-D network structure of the Upper Ordovician Pagoda Formation in South China, as investigated by Zhan et al. （Palaeogeography, Palaeocli-matology, Palaeoecology, DOI： 10.1016/j.palaeo.2015.07.039）.
基金supported by Chinese Academy of Sciences (Grant No. KZCX2-YW-Q05-01)National Natural Science Foundation of China(Grant No. 40825006)the CAS/SAFEA International Partnership Program for Creative Research Teams and the State Key Laboratory of Paleobiology and Stratigraphy
文摘Eospirifer,the oldest known genus of the spiriferide group(Brachiopoda),first appeared on the Zhe-Gan Platform of South China paleoplate during late Katian(Late Ordovician) represented by E.praecursor.It survived the end-Ordovician mass extinction,and reappeared on the Upper Yangtze Platform of South China paleoplate by the end of Ordovician near the upper part of the Normalograptus persculptus Biozone.Starting from the beginning of Silurian,Eospirifer experienced some morphological innovations and expanded its geographical distribution substantially.It reached its species diversity acme and the widest geographic distribution in Wenlock(middle Silurian),with the diversity hotspots in Laurentia,Avalonia,and Baltica.Various shell size frequency curves of E.praecursor under different paleogeographic settings suggest that this pioneer species of Eospirifer,with several macroevolutionary novelties,adopted a range of life strategies to adapt to the changing environments during early spiriferide evolution.There are also some morphological macroevolutionary trends during the evolutionary history of Eospirifer from Late Ordovician to the end of Silurian,such as the ever enlarging shell sizes and the width/length ratios from late Katian to Wenlock,but decreasing apparently of both parameters from Wenlock to Pridoli.
