【摘要】 1992年5月-1992年6月对冲绳海槽热液活动区进行调查采样，对拖网采到的新鲜的玄武岩样品做了斑晶矿物学及岩石化学研究。结果表明，冲绳海槽玄武岩的斑晶矿物主要由橄榄石、单斜辉石、斜方辉石和斜长石（An=69％－86％）组成，副矿物有铬铁尖晶石和磁铁矿，因而将样品定名为橄榄玄武岩。同大洋中脊玄武岩相比，冲绳海槽玄武岩明显具有E型洋脊玄武岩的特征，说明初始岩浆可能来自由于海槽扩张而隆升的地幔。更多还原

【Abstract】 Preliminary studies on the mineralogy and petrochemistry of basalt samples collected in May of 1992 from the environs of submarine hydrothermal vents in the Okinawa Trough, a typical backarc spreading basin where acidic pumice (SiO2≈70%) is known to be widely distributed, showed that the samples were the tholeiitic magma eruption products. On petrochemistry and trace element (including REE) compositions, the basalt have characteristics of E-type MORB.The basalt has porphyritic texture comporised of phenocrysts of chrysolite (>50 % ), pyroxene (≈ 35 %, clinopyroxene dominant), plagioclase (≈ 10 % ), and spinel alld magnetite as accessory plienocryst minerals. On Feveral rock series identification diagrams the samples were projected in the area of tholeiite, so mineralogically and petrochemically named as dorgalite. The origin of the basaltic magma activity and the significances to the tectonic setting of the trough are discussed.更多还原