• 责任者：Yu Miao (School of Ocean Sciences ; China University of Geosciences ; Beijing 100083 ; China) ; Su Xin
• 刊名：Earth Science Frontiers
• 出版年：2013
• 卷期：20(5
• 关键词：矿物学 ; mineralogy ; 洋中脊玄武岩 ; mid-ocean ridge basalts ; 东太平洋 ; East Pacific
• 页码：p.87-105
• 图表：13 illus., 13 tables, 59 refs.
• 分类号：0801
• issnNo：ISSN1005-2321
• isbnNo：CN11-3370/P

     We analyzed the basalt samples from 3 localities between 1.23°N and 5.70°S along the East Pacific Rise （EPR）, which were collected through television-video guided grab （TVG） during three hydrothermal expeditions of Chinese vessel ＂Da Yang Yi Hao＂ between 2009 and 2011. Basalts from the EPR can be classified into two types. Basalts from EPR（A） are incompatible element enriched-mid ocean ridge basalts （E MORBs）, while basalts from the other two areas are normal mid-ocean ridge basalts（N-MORBs）. The samples from EPR（A） are coarse grained with large amount of euhedral plagioclase phenocrysts. The whole rock major elements of samples from EPR（A） are high in Al2O3 and low in total FeO and MgO. Inclusion morphology in plagioclase of EPR（A） basalts suggests that the magmas flow fastly during the plagioclase crystallization and have been fractionated before plagioclase crystallization. On the other hand, the samples from EPR（B） and EPR（C） are N MORBs with higher TFeO and MgO, and less amount of plagioclase phenocrysts which are also smaller in size compared with that from EPR （A）. Basaltic magma source of EPR（A） is located in a shallow level and has undergone intensive magma mixing-crystallization. There are probably 3-times of magma mixing in this area accompanying with the accumulation of plagioclase phenocrysts and the magma is of high viscosity and low density. The magmas from the other two areas may come from a deeper level and have undergone less times of magma mixing. The Sr and Eu elemental features together with the petrographic features show that the magma may have undergone a high-pressure clinopyroxene extraction whereas plagioclase has not been extracted but tended to be enriched.