Geochemical and Mineralogical Investigation on Different Types of Cenozoic Basalts in the Sanshui Basin:Implications for Magma Mixing Processes  

作　　者：Wei Zhang Nianqiao Fang Xiaobo Yuan Lukai Cui 

机构地区：[1]Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao 266071,China [2]School of Ocean Sciences,China University of Geosciences,Beijing 100083,China [3]College of Earth Sciences,East China Institute of Technology,Nanchang 330013,China

出　　处：《Journal of Earth Science》2019年第4期754-762,共9页地球科学学刊（英文版）

基　　金：financial supported by the National Natural Science Foundation of China (Nos. 41276047, 41030853, 41572207, 41440041);the Special and Frontier Foundation for the Twelve Five Plan of the China Ocean Mineral Resources Research and Development Association (No. DY125-22-QY-21)

摘　　要：Two kinds of basalts with different chemical compositions were obtained in the Sanshui Basin,they share the same eruption period. Although they have significant differences in major and trace element concentrations,their isotopic ratios suggest a similar magma source. Based on mineral geochemical analysis,orthopyroxene with reaction rim and zoned clinopyroxene are observed in Zidong(ZD)basalts,but not found in Wangjiegang(WJG) basalts. Linear scanning of these minerals suggests compositional variation between within-plate tholeiite and within-plate alkali-basalt. Presence of a doublelayer magma chamber under the Sanshui Basin,and occurrence of magma mixing between upper and lower chambers is proposed. This magma mixing leads to different chemical composition and mineral constitution of two kinds of basalts,as well as reaction rim and compositional variation of minerals in ZD basalts.Two kinds of basalts with different chemical compositions were obtained in the Sanshui Basin, they share the same eruption period. Although they have significant differences in major and trace element concentrations, their isotopic ratios suggest a similar magma source. Based on mineral geochemical analysis, orthopyroxene with reaction rim and zoned clinopyroxene are observed in Zidong(ZD)basalts, but not found in Wangjiegang(WJG) basalts. Linear scanning of these minerals suggests compositional variation between within-plate tholeiite and within-plate alkali-basalt. Presence of a doublelayer magma chamber under the Sanshui Basin, and occurrence of magma mixing between upper and lower chambers is proposed. This magma mixing leads to different chemical composition and mineral constitution of two kinds of basalts, as well as reaction rim and compositional variation of minerals in ZD basalts.

关 键 词：Sanshui Basin ALKALI BASALT THOLEIITE MAGMA mixing MAGMA chamber geochemistry 

分 类 号：P[天文地球]