Geochemical and Mineral Characteristics of Jurassic Volcanic Rocks from ODP Sites 304, 1149, and 801:Implications for Magmatic Evolution in the Northwest Pacific

作     者：CHEN Shuangshuang LIU Jiaqi Patrick RIOUAL GUO Zhengfu 

作者机构：Key Laboratory of Cenozoic Geology and Environment Institute of Geology and Geophysics Chinese Academy of Sciences State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Institutions of Earth Science Chinese Academy of Sciences 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2018年第92卷第3期

页      面：915-934页

核心收录：

学科分类：070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 0819[工学-矿业工程] 07[理学] 070901[理学-矿物学、岩石学、矿床学] 0818[工学-地质资源与地质工程] 0708[理学-地球物理学] 0816[工学-测绘科学与技术] 

基　　金：supported by the National Natural Science Foundation of China (Grant code: 41476034, 41272369, 40802038, and 41320104006) research funds from State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences (Grant code: 81300001) 

主　　题：tholeiite zoning texture Ocean Drilling Program plate spreading rate Northwest Pacific 

摘      要：The regular variations in magmatic activities along the Northwest Pacific plate have been little studied in spite of their importance. In this contribution, systematic analyses were conducted on tholeiitic basalts from three Ocean Drilling Program sites(Sites 304, 1149, and 801), including the petrographic features, major and trace elements, Nd isotopic compositions, and mineral structure and compositions of whole rocks. Volcanic rocks from Sites 304, 1149, and 801 belong to tholeiites and exhibit depleted light rare earth elements(LREE), large ion lithophile elemental contents(LILE), and relatively depleted Nd isotopic ratios(143Nd/144Nd=0.513139-0.513211), similar to those of normal mid-ocean ridge basalts(NMORB). Comprehensive data on mineral compositions, whole-rock geochemistry, and geochronology demonstrate that a regular variation trend exists in the north-south direction along the Northwest Pacific plate. The 143 Nd/144 Nd values(0.513139-0.513211) and trace-element ratios for whole rocks(Sm/Th=15.35-30.00; Zr/Hf=28.53-35.76; Zr/Y=2.58-3.67; Th/La=0.04-0.06; Th/Y=0.33-0.70), as well as the trace-element ratios(Zr/Hf, La/Yb, Ti/Zr) of clinopyroxenes from Sites 1149 and 801 tholeiites show larger variations compared to those from Site 304 tholeiites(143Nd/144Nd=0.513185-0.513195; Sm/Th=18.19-20.58; Zr/Hf=31.07-33.26; Zr/Y=2.62-3.03; Th/La=0.05-0.06; Th/Y=0.48-0.57). Mineral zoning textures were obvious in tholeiites from Sites 1149 and 801 but were rarely observed in Site *** regular features were likely attributed to the differences in the heterogeneity of the magma source,the process of magmatic evolution, the plate-spreading rate, and the effective and ineffective mixing.