Paleomagnetism of early Paleozoic volcanic rocks from the Beishan area,Gansu of northwest China:Preliminary insight into early Paleozoic kinemics of the Beishan terrane  

作　　者：Baochun Huang Yongcheng Wang Rixiang Zhu Fuqin Zhang 

机构地区：[1]Acad Sinica, Inst Geol & Geophys, Beijing 100101, Peoples R China

出　　处：《Chinese Science Bulletin》2002年第18期1561-1567,共7页

基　　金：Thiswork was supported by the Chinese Academy of Sciences (Grant No. KZCX2-104) ;the National Natural Science Foundation of China (Grant No. 49874014).

摘　　要：We report rock magnetic and paleomagnetic results for Middle Silurian Gongpoquan and Middle Ordo-vician Huaniushan volcanic samples collected from the Ma-zongshan and Hongliuyuan areas of Gansu Province, northwest China. The results indicate that the main magnetic mineral of the Gongpoquan and Huaniushan volcanic rock is magnetite, and it may remain characteristic remanent magnetization acquired at the time of formation of the rocks. However, with the exception of samples from site go20, most of Middle Ordovician Huaniushan volcanic samples have a very weak nature remanent magnetization, and generally show an erratic demagnetization behavior, which does not allow isolation of characteristic remanent magnetizations from these samples. Comparison of paleomagnetic results obtained from the Beishan area of Gansu with Paleozoic apparent polar wander paths for Tarim and Siberia suggests that the Beishan tarrane, the southern part of the Beishan area of Gansu beyond the Mingshui-Shipanjin-Xiaohuang-shan zone,We report rock magnetic and paleomagnetic results for Middle Silurian Gongpoquan and Middle Ordovician Huaniushan volcanic samples collected from the Mazongshan and Hongliuyuan areas of Gansu Province, north-west China. The results indicate that the main magnetic mineral of the Gongpoquan and Huaniushan volcanic rock is magnetite, and it may remain characteristic remanent magnetization acquired at the time of formation of the rocks. However, with the exception of samples from site go20, most of Middle Ordovician Huaniushan volcanic samples have a very weak nature remanent magnetization, and generally show an erratic demagnetization behavior, which does not allow isolation of characteristic remanent magnetizations from these samples. Comparison of paleomagnetic results obtained from the Beishan area of Gansu with Paleozoic apparent polar wander paths for Tarim and Siberia suggests that the Beishan tarrane, the southern part of the Beishan area of Gansu beyond the Mingshui-Shipanjin-Xiaohuangshan zone, and adjacent Tarim block and Siberia plate could not have been connected in their present configuration by the Middle Silurian time. On the other hand, we infer that the early Paleozoic Mingshui-Shipanjin-Xiaohuangshan oceanic basin may open from west to east during period from the Ordovician to Silurian, and the post-Middle Silurian closing of this oceanic basin may result from a progressed eastward scissor-like rotation

关 键 词：Beishan area of GANSU Early PALEOZOIC rock MAGNETISM and paleomagnetism. 

分 类 号：P588.1[天文地球—岩石学]