东太平洋海隆近赤道区玄武岩岩石地球化学与地幔源区特征  

Mantle Source Featrues of the Basalts and Magma Activity Along the Equatorial Regions in the East Pacific Rise

作　　者：韩宗珠[1,2] 刘涵 李敏[2] 孙晓霞[1,2] 来志庆[1,2] 边宇 林学辉 HAN Zong-Zhu;LIU Han;LI Min;SUN Xiao-Xia;LAI Zhi-Qing;BIAN Yu;LIN Xue-Hui(College of Marine Geosciences,Ocean University of China,Qingdao 266100,China;ey Laboratory of Science and Technology of Submarine Detection,Ministry of Education,Ocean University of China,Qingdao 266100,China;Qingdao Institute of Marine Geology,Qingdao 266071,China)

机构地区：[1]中国海洋大学海洋地球科学学院,山东青岛266100 [2]中国海洋大学海底科学与探测技术教育部重点实验室,山东青岛266100 [3]中国地质调查局青岛海洋地质研究所,山东青岛266100

出　　处：《中国海洋大学学报（自然科学版）》2018年第1期63-75,共13页Periodical of Ocean University of China

基　　金：国家自然科学基金项目(41376053);中国海洋大学国家大学生创新训练项目(201210423030)资助~~

摘　　要：本文对东太平洋海隆赤道地区北部和南部的9件玄武岩样品进行了详细的岩相学和主量、微量元素及Sr-Nd-Pb同位素分析研究,结果表明:MgO含量为7.32%~10.22%,Na_2O为3.03%~3.59%,K_2O为0.23%~0.57%,CaO为10.96%~12.39%,Al_2O_3为11.40%~13.76%,该区玄武岩均属于亚碱性玄武岩,具有MORB型的稀土及微量元素特点,原始岩浆均经历了橄榄石和斜长石的分离结晶。轻重稀土元素含量均较低,LREE/HREE比值为0.61~0.97,(La/Yb)N比值为0.72~1.76,(La/Sm)N比值为0.60~1.30,(Gd/Yb)N为0.99~1.16。Sr-Nd-Pb同位素特征更接近NMORB,其中,87Sr/86Sr和143 Nd/144 Nd比值更接近DM源区,而Pb的三种同位素比值要明显高于DM源区,更为接近EM源区。研究表明岩浆起源于尖晶石橄榄岩区,来源于较为亏损的地幔,NEPR玄武岩可能混有HIMU源区,SEPR玄武岩除了混合有HIMU成分外,可能还有少量的EMⅡ成分。In order to understand the cause and origin of the basalt in the rapid expansion area,in this study 9 basalts samples near the East Pacific Rise(EPR)were analyzed to investigate the evolutionary process of basalts in this area.we analyzed the mineralogy,whole-rock major,trace elements and Sr-Nd-Pb isotopic compositions.The ratio of MgO is 7.32%~10.22%;Na 2O is 3.03%~3.59%;K 2O is 0.23%~0.57%;CaO is 10.96%~12.39%,Al 2O 3 is 11.40%~13.76%,This field is made up of subalkaline basalt.They have the characteristics of MORB type of REE and trace elements.The basalts were mantle-derived magmas with the fractional crystallization of olivine and plagioclase.The ratio of LREE/HREE is 0.61~0.97;(La/Yb)N is 0.72~1.76,(La/Sm)N is 0.60~1.30,(Gd/Yb)N is 0.99~1.16.The variation of 87 Sr/86 Sr is 0.702 096~0.702 428;143 Nd/144 Nd is 0.513 153~0.513 303;208 Pb/204 Pb is 37.603 2~38.208 7;207 Pb/204 Pb is 15.489 2~15.566 5;206 Pb/204 Pb is 17.845 8~18.266 8.It is shows that magma originated in spinel peridotite area.It is derived from the loss of the mantle,including NEPR basalt may be mixed with HIMU source area,SEPR basalt mixed with HIMU and a little EMⅡ.

关 键 词：东太平洋海隆 玄武岩 岩浆作用 结晶分异作用 

分 类 号：P591[天文地球—地球化学]