Structure and evolution of Middle Permian palaeo- seamounts in Bayan Har and its adjacent area  

作　　者：WANG Yongbiao 

机构地区：[1]Faculty of Earth Science, China University of Geosciences and State Key Laboratory of Geological Processes and Mineral Resources, Wuhan 430074, China

出　　处：《Science China Earth Sciences》2005年第11期1848-1858,共11页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.40172013).

摘　　要：Middle Permian palaeo-seamounts in the area of Bayan Har are generally com-posed of volcanic basement and carbonate cap. Basaltic lava, volcanic breecia and polymictic breccia can be identified as the main kinds of rock in the basement of palaeo-seamounts. Mas-sive bioclastic limestone and reef framestone formed the carbonate cap of the palaeo-sea- mounts. The contact relationship between carbonate cap and volcanic basement is a kind of conformity or depositional unconformity. Study of the structure and petrology of palaeo-sea- mounts suggests that the evolution history of the palaeo-seamounts in this area can be divided into five stages at least. They are the origin of the first volcanic basement, the formation of the first carbonate cap, the breaking of the first carbonate cap by renewed volcanism, the deposition of red calcareous mudstone and the rebuilding of the second carbonate cap at last. In one of the palaeo-seamounts, volcanic activation took place even after the reconstruction of the second carbonate cap. Lots of fusulinid fossils, such as Neoschwagerina craticulifera Schwager, Schwagerina sp. and Verbeekina sp., were found both in the carbonate cap and volcanic base-ment, showing that the palaeo-seamounts were originated and developed within the Maokou stage of Middle Permian.Middle Permian palaeo-seamounts in the area of Bayan Har are generally com-posed of volcanic basement and carbonate cap. Basaltic lava, volcanic breecia and polymictic breccia can be identified as the main kinds of rock in the basement of palaeo-seamounts. Mas-sive bioclastic limestone and reef framestone formed the carbonate cap of the palaeo-sea- mounts. The contact relationship between carbonate cap and volcanic basement is a kind of conformity or depositional unconformity. Study of the structure and petrology of palaeo-sea- mounts suggests that the evolution history of the palaeo-seamounts in this area can be divided into five stages at least. They are the origin of the first volcanic basement, the formation of the first carbonate cap, the breaking of the first carbonate cap by renewed volcanism, the deposition of red calcareous mudstone and the rebuilding of the second carbonate cap at last. In one of the palaeo-seamounts, volcanic activation took place even after the reconstruction of the second carbonate cap. Lots of fusulinid fossils, such as Neoschwagerina craticulifera Schwager, Schwagerina sp. and Verbeekina sp., were found both in the carbonate cap and volcanic base-ment, showing that the palaeo-seamounts were originated and developed within the Maokou stage of Middle Permian.

关 键 词：palaeo-seamounts  MIDDLE Permian  Bayan Har 

分 类 号：N[自然科学总论]