冲绳海槽中段沉积物物源识别及其热液活动指示

冲绳海槽中段热液活动区表层沉积物的主、微量和稀土元素分析结果表明:区内沉积物主要由陆源物质与热液源物质组分组成,Hg、Au、Sb、Cu、Pb、Zn、Ba、As、Fe和Co等微量元素富集;沉积物的化学风化程度中等,A-CN-K图解表明其暂未受到钾交代影响,且其母岩成分接近花岗闪长岩;北美页岩标准化稀土配分模式曲线整体较为...

Provenance identification of sediments in the central Okinawa Trough and its implications for hydrothermal activity

Surface samples in hydrothermal fields of the central Okinawa Trough are analyzed for major and trace element composition. Results propose that the samples are mainly composed of terrestrials and hydrothermal materials. The deposits are an enrichment of trace elements such as Hg, Au, Sb, Cu, Pb, Zn, Ba, As, and Co, which have moderate chemical alteration index (CIA) values and are not affected by potassium replacement. The A-CN-K diagram shows that the parent rock composition is close to granodiorite. The standardization rare earth elements (REE) distribution pattern of North American Shale is relatively flat, which implies the slight fraction between light-group rare earth elements (LREE) and heavy-group rare earth elements (HREE). Part of samples have positive Eu anomalies similar to those of hydrothermal fluids. Under the influence of hydrothermal activity, some sediments are prominently enriched in Fe, Cu, As, Pb, and Zn. Combined with the location of the samples, the spatial distribution shows a pattern of metalliferous sediments-transitional sediments-normal sediments. This pattern and ratios of (La/Sm)_N and (La/Yb)_N indicate that the terrigenous component of the samples in the central Okinawa Trough comes mainly from the Yellow River and Taiwan island river.