Petrology and geochemistry of South Mid-Atlantic Ridge(19°S) lava flows:Implications for magmatic processes and possible plume-ridge interactions

作     者：Haitao Zhang Xuefa Shi Chuanshun Li Quanshu Yan Yaomin Yang Zhiwei Zhu Hui Zhang Sai Wang Yili Guan Renjie Zhao Haitao Zhang;Xuefa Shi;Chuanshun Li;Quanshu Yan;Yaomin Yang;Zhiwei Zhu;Hui Zhang;Sai Wang;Yili Guan;Renjie Zhao

作者机构：Key Laboratory of Marine Sedimentology and Environmental GeologyFirst Institute of OceanographyMinistry of Natural and ResourcesQingdaoShandong266061China Laboratory for Marine GeologyQingdao National Laboratory for Marine Science and TechnologyQingdaoShandong266061China College of Earth Science and EngineeringShandong University of Science and TechnologyQingdao266590China National Deep Sea CenterMinistry of Natural and ResourcesQingdao266061China 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2020年第11卷第6期

页      面：1953-1973页

核心收录：

学科分类：070704[理学-海洋地质] 0709[理学-地质学] 07[理学] 0707[理学-海洋科学] 

基　　金：supported by National Natural Science Foundation of China(Grants Nos.41706060,41506047,41776070,41322036,41506079) China Ocean Mineral Resources R&D Association Project(Grant Nos.DY135-S2-2,DY135-S22-01) Taishan Scholarship from Shandong Province 

主　　题：Magmatic process Mantle potential temperature Crystallization pressure Plume-ridge interaction South Mid-Atlantic Ridge 

摘      要：The South Mid-Atlantic Ridge(SMAR)19°S segment,approximately located along the line of Saint Helena volcanic chain(created by Saint Helena mantle plume),is an ideal place to investigate the issue whether the ridgehotpot interaction process affected the whole *** this study,we present major and trace elemental compositions and Sr-Nd-Pb isotopic ratios of twenty fresh lava samples concentrated in a relatively small area in the SMAR 19°S *** oxides compositions show that all samples are *** contents of compatible trace elements(e.g.,Ni=239-594 ppm and Cr=456-1010 ppm)and low Fe/Mn(54-67)and Ce/Yb(0.65-1.5)ratios of these lavas show that their parental magmas are partially melted by a spinel lherzolite mantle *** software PRIMELT3,this study obtained mantle potential temperatures(Tp)beneath the segment of1321-1348℃,which is lower relative to those ridges influenced by mantle *** asthenospheric mantle beneath the SMAR 19°S segment starts melting at a depth of^63 km and ceases melting at^43 km with a final melting temperature of^1265℃.The extent of partial melting is up to 16%-17.6%with an average adiabatic decompression value of 2.6%/*** correlations of major oxides(CaO/Al2 O3)and trace elements(Cr,Co,V)with MgO and Zr show that the parental magma experienced olivine and plagioclase fractional crystallization during its ascent to the surface.87Sr/86Sr(0.702398-0.702996),143 Nd/144 Nd(0.513017-0.513177)and 206Pb/204Pb(18.444-19.477)ratios of these lavas indicate the mantle source beneath the SMAR 19°S segment is composed of a three-component mixture of depleted MORB mantle,PREMA mantle,and HIMU mantle *** simple,binary mixing results among components from plume-free SMAR MORB,Saint Helena plume and Tristan plume show that asthenospheric mantle beneath the SMAR 19°S segment may be polluted by both Saint Helena and Tristan plume enriched *** abovementioned mantle potential temperatures,together with the low Sai