富Co铁锰结壳铂族元素与铼-锇同位素组成及其意义

用ICP－MS测定了太平洋富Co铁锰结壳铂族元素和铼－锇同位素组成。富Co铁锰结壳不仅异常富集铂族元素，而且铂族元素及其它亲铁元素的配发与陨石特征非常相似。铁锰结壳的铼－锇同位素组成明显有别于大陆地壳岩石，和K－T界线沉积物相似，接近陨石值。世界大洋范围内的富Co铁锰结壳均产于远离海底构造热液活动区，几乎不可能受到地幔源热液作用的直接影响。因此，富Co铁锰结壳中的铂族元素可能部分来源于地外物质。

PGE AND Re-Os ISOTOPE COMPOSITIONS AND THEIR SIGNIFICANCES OF CO-RICH FERROMANGANESE CRUSTS

The platinum group element and Re Os isotope compositions of ferromanganese crusts from the Middle and Western Pacific were determined with ICP MS. Cobalt rich ferromanganese crusts are significantly rich in platinum group elements, and the partition of platinum group elements in cobalt rich ferromanganese crusts is very similar to that of meteorite. The Re Os isotope composition is obviously different from the rocks of the continental crust, but similar to the K T boundary sediment, and close to the meteorite. Cobalt rich ferromanganese crusts could not be influenced by mantle sourced hydrothermal process as all oceanic cobalt rich ferromanganese crusts grow on the seamounts away from seafloor hydrothermal activity sites. Therefore, it is clearly possible that extra teristitial platinum group elements exist in cobalt rich ferromanganese crusts.