Chemical and isotope compositions of main phases of metalliferous sediments from holes of DSDP Leg 92@en

The carbonate-free metalliferous fraction of thirty-nine sediment samples from four DSDP Leg 92 sites has been analyzed for 12 elements, and a subset of 16 samples analyzed for Pb isotopic composition. The main geochemical features of this component are as follows: i) very high concentrations of Fe and Mn, typically 25-39% and 5-14%, respectively; ii) Al and Ca contents generally less than 2% and 5%, respectively; iii) high Cu (1000-2000 ppm), and Zn and Ni (500-1000 ppm) values; and iv) Co and Pb concentrations of 100-250 ppm. In terms of element partitioning within the metalliferous fraction, amorphous to poorly crystallized oxide-oxyhydroxides removed by the second leach carry virtually all of the Mn, and about 90% of the Ca, Sr and Ni. The well-crystallized goethite-rich material removed by the third leach carries the majority of Fe, Cu, and Pb. These relations hold for sediments as young as ~1-2 Ma, indicating early partitioning of hydrothermal Fe and Mn into separate phases. […]对来自深海钻探计划（Deep Sea Drilling Project，DSDP）第92航次4个站位的39个沉积物样品的无碳酸盐金属组分，开展了12种元素的含量分析，并选取其中16个样品完成了铅同位素组成测定。该金属组分的主要地球化学特征如下：① 铁（Fe）与锰（Mn）含量极高，通常分别为25%~39%与5%~14%；② 铝（Al）、钙（Ca）含量普遍低于2%与5%；③ 铜（Cu）含量达1000~2000 ppm，锌（Zn）与镍（Ni）含量为500~1000 ppm；④ 钴（Co）与铅（Pb）含量介于100~250 ppm之间。针对该金属组分内的元素分配行为，第二次浸提步骤所去除的无定形至弱结晶态氧化物-羟基氧化物相中，几乎承载了全部的锰，以及约90%的钙、锶（Sr）与镍；第三次浸提步骤所分离出的结晶度良好的富针铁矿组分，则承载了大部分的铁、铜与铅。上述元素分配关系在年龄约1~2 Ma的沉积物中依然成立，表明热液成因的铁与锰会早期分配至不同的物相之中。[…]