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对近年来我国“大洋一号”科考船在西南印度洋中脊(SWIR)多金属硫化物调查区4个站位所获得的玄武岩进行了岩石学及元素地球化学研究。其岩相学特征为以斑状结构为主,斑晶矿物主要由斜长石、辉石和橄榄石组成。基质以间隐结构为主,主要由斜长石、橄榄石和辉石微晶组成。全岩元素地球化学分析结果表明样品属于亏损型洋中脊玄武岩。矿物化学成分表明斜长石主要为倍长石和拉长石,橄榄石为贵橄榄石。研究区玄武岩具低的Na8、K/Ti比值和LREE/HREE以及较高的Fe8值,可整体归入SWIR 49°E-70°E区指示岩浆熔融程度最高、熔融深度最深的区域内。本次研究为探索SWIR洋脊玄武岩和岩浆熔融等相关研究提供了49.6°E和50.5°E区的新资料,也指示了区内岩浆活动或成矿围岩物质来源的复杂性。
In recent years, China “Ocean One ” scientific research ship basalt obtained in four stations of Southwest Indian Ocean Ridge (SWIR) polymetallic sulphide survey area for petrology and elemental geochemistry. Its lithology is characterized by a patchy structure, and plagioclase minerals are mainly composed of plagioclase, pyroxene and olivine. The matrix is dominated by interlaced structure, mainly composed of plagioclase, olivine and pyroxene crystallites. The whole rock element geochemical analysis results show that the samples belong to depleted mid-oceanic ridge basalts. The chemical composition of the minerals indicates that plagioclase is predominately palygorskite and labradorite, and olivine is peridotite. The low Na8, K / Ti ratio, LREE / HREE and high Fe8 of basalts in the study area can be classified as a whole in the SWIR 49 ° E-70 ° E area, indicating that the magma has the highest degree of melting and the deepest melt depth. The present study provides new data for the study of SWIR ocean ridge basalts and magmatic melting and other related studies at 49.6 ° E and 50.5 ° E, and also indicates the complexity of magmatism or the source of ore-forming rocks in the area.