中文摘要：

在莱恩海山链MP2海山的一块富钴结壳样品新壳层中,发育有＂褐红色碎屑物质＂,这种物质粒度细小,呈浸染状分布,以Fe-Mn壳层柱状结构间的填隙物的形式产出。基于对该海区结壳样品手标本和光片的观察,认为这种＂褐红色碎屑物质＂可作为新壳层的一个标志物。利用电子探针技术,对这块富钴结壳样品进行了分析,获得了该结壳新壳层中＂褐红色碎屑物质＂及其周边Fe-Mn壳层的成分数据,Fe、Mn元素含量的面扫描数据和新壳层成分数据。数据显示,MP2海山富钴结壳样品新壳层属于典型的水成成因铁锰沉积,其中发育的＂褐红色碎屑物质＂的成分以Fe、Si、Al为主,而Mn含量相对Fe-Mn壳层则非常低。据其成分特点、形态和MP2海山所处高生产力的古海洋背景,认为这种结壳新壳层的＂褐红色碎屑物质＂最可能为海洋中自生的Fe-Si-Al胶体沉积。

英文摘要：

A reddish-brown detrital material has been discovered,which is obviously younger than the Co-rich ferromanganese crust,from the seamount MP2 of the Line Islands.The material is fine in grain size,and occurs in the interstices between the columns of Fe-Mn oxides.Based on the observation of hand specimen and polished sections of Co-rich ferromanganese crusts from the Line Islands,it can be concluded that this reddish-brown detrital material can be used as a marker of a younger deposit in ferromanganese crusts.The reddish-brown detrital material and the Fe-Mn oxides around it were investigated geochemically by electron-probe microanalysis（EPMA）.EPMA data suggest that the Co-rich ferromanganese crust is hydrogenetic in origin,and the chemical composition of the reddish-brown detrital material is characterized by Fe,Si and Al,and a lower Mn in comparison with the Fe-Mn oxides around it.Base on the geochemical characteristics and morphology of the reddish-brown detrital material,and with reference to the high primary productivity in the area around the seamount MP2,it is supposed that the reddish-brown detrital material is most probably a kind of authigenic Fe-Si-Al colloidal precipitation from seawater younger than the Co-rich ferromanganese crusts.