麦哲伦海山链富钴结壳成矿区域地质背景

THE REGION GEOLOGICAL BACHGROUND OF COBALT-RICH CRUST FORMATION FORM THE MAGELLANEAN SEAMOUNT CHAIN

本文根据我国调查成果和充分利用DSDP资料,通过综合研究分析认为:麦哲伦成矿区,实际上是一条呈北西方向展布的、规模宏大的海山链。该海山链包含十多座海山,每座海山均属平顶山类型。几乎每座海山都具有从山顶往下,由平坦→陡峭→缓坡变化的规律。即山顶平坦,海山上、中部山坡陡峭,海山中、下部山坡变缓。依据海山形态和其坡度的变化特点,每座海山可划分出台地、陡坡带和缓坡带等三个地貌单元,根据区域地层和海洋磁异常条带(M_(25)M_(38))展布特征综合分析,推断麦哲伦海山链所在的位置,原来是一条规模宏大的、走向北西的转换断层。该断层控制着麦哲伦海山链富钴结壳的成矿作用。

Based on the R/V Haiyang IV investigation and the deep-sea drillings information, the Magellanean Seamount area usually is a sweeping seamount chain, which contains of more ten volcanic seamount . The seamount chain is bearing WN-ES. Each of the seamount was proved by sounding results to consist of the following 3 geomorphic unit: ① mesa on top of the seamount; ② escarpment belt on the central-upside slope of the seamount; ③ delay sloping hell on the below-central slop belt of the seamount. From the regional stratum and distributing characteristic of the ocean magnetic anomaly lineations (M_(25)-M_(38)), which are progeny by DSDP and physical geography sea valley, it is conclued that the position of the seamount chain was a transitional fault. There were five vio- lent active volcanic stages along the transitional fault age, Which are, in ascending order, The alkali basalte and tholeiite in Middle Jurassic, alkali basalt in late Jurassic, alkali basalt and vol- caniclastic in Early Cretaceous, basalt and volcaniclaslic in late Cretaceous, lava and volcano in the Oligocene-Miocene. It is shown by the region geological background that the thickness and abundance of the cobalt-rich crust in southeast segment are greater than the northwest segment from the Magel- lanean Seamount Chain.