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为了探讨富钴结壳的稀土和铂族元素是否有相似的形成机制,对西太平洋海山富钴结壳稀土和铂族元素进行了类比研究.结果表明:富钴结壳的∑REY范围为1 433.7×10-6~2 888.0×10-6,其中Ce占到近50%,北美页岩标准化后显示较平坦的稀土模式和显著的Ce正异常特征.根据稀土配分模式及已有的Nd同位素结果,富钴结壳具有亲陆壳属性.富钴结壳具有极高的Pt(115.5×10-9~1 132.0×10-9)、(Pt/Pd)N和(Pt/Os)N值,Ir与Pt及Rh与Pt显示良好相关性.经球粒陨石标准化后显示较一致PGE(platinum-group elements)配分模式,从Os到Pt逐渐富集,Pd元素强烈亏损.已有的Os同位素研究结果显示物源在地质历史时期从幔源属性向陆源属性变化,但富钴结壳PGE元素内部相对含量仍在一定程度上保持稳定.研究认为:富钴结壳对海水中的稀土清扫具有选择性,Ce的正异常恰恰是结壳对海水稀土中Ce的优先选择造成的,从而导致海水亏损Ce.然而海水中Ce的亏损并未改变新形成富钴结壳的稀土模式,原因是在海洋中存在适量的具有亏损Ce特征的磷酸盐等组分,理论上只需要氧化物类稀土与磷酸盐类稀土消耗的稀土与海水中的补给平衡即可.只是在相关过程中,海洋中氧化物类对稀土的选择更具有主动性,而磷酸盐类表现更多的继承关系.尽管Os同位素显示物源供给发生变化,然而富钴结壳PGE模式相对稳定.因此富钴结壳PGE模式同样可以用富钴结壳对PGE的选择性吸收解释,因富钴结壳优先选择Pt与Ir以及相对排斥Pd和Os,形成了现有独特的PGE模式.
In order to explore whether the rare earth and platinum group elements of cobalt-rich crusts have similar formation mechanism, the rare earth and platinum group elements in cobalt-rich crusts of the western Pacific seamount are studied analogously.The results show that the ΣREY range of cobalt-rich crusts is 1 433.7 × 10-6 ~ 2 888.0 × 10-6, of which Ce accounted for nearly 50%, North American shale normalization shows a relatively flat RE pattern and significant Ce positive anomaly characteristics.According to RE patterns and existing Nd isotopes As a result, the cobalt-rich crust has the properties of a pro-continental crust, with extremely high Pt (115.5 × 10-9 ~ 1 132.0 × 10-9), (Pt / Pd) N and , And Ir and Pt and Rh showed good correlation with Pt.It was shown that the more uniform PGE (platinum-group elements) partitioned mode from chondrite to meteorite gradually enriched from Os to Pt, and the Pd element was strongly depleted.The existing Os isotope The results show that the source material changed from the mantle source attribute to the terrigenous source attribute during geologic history, but the relative content of PGE in the cobalt-rich crust is still stable to a certain degree.Research shows that the cobalt-rich crust has the potential of Selectively, the positive anomaly of Ce is precisely the preferential choice of Ce in crusts to rare earths, which leads to Water loss Ce. However, the loss of Ce in seawater did not change the rare earth pattern of newly formed cobalt-rich crust because there are some components such as phosphates with depleted Ce characteristic in the ocean. Theoretically, only the oxide rare earths And phosphates rare earth depleted by the supply of rare earth and seawater balance can be just in the relevant process, the ocean of oxides on the choice of rare earth more active, while the performance of more inheritance of phosphate .Although the Os However, the PGE mode of cobalt-rich crust is relatively stable, so the PGE mode of cobalt-rich crust can also be explained by the selective absorption of cobalt-rich crust for PGE because the cobalt-rich crust preferentially selects Pt and Ir And the relative exclusion of Pd and Os, the formation of the existing unique PGE model.