COBALT-RICH AND PLATINUM-RICH FERROMANGANESE CRUSTS AND ASSOCIATED SUBSTRATE ROCKS FROM THE MARSHALL-ISLANDS
COBALT-RICH AND PLATINUM-RICH FERROMANGANESE CRUSTS AND ASSOCIATED SUBSTRATE ROCKS FROM THE MARSHALL-ISLANDS
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DOI：
10.1016/0025-3227(88)90113-2
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发表时间：
1988-01-01
期刊：
影响因子：
2.9
通讯作者：
DAVIS, AS
中科院分区：
文献类型：
--
作者：
HEIN, JR;SCHWAB, WC;DAVIS, AS
铁锰结壳覆盖了太平洋中部盆地海底建筑物的大部分坚硬基质。讨论了马绍尔群岛拉塔克链沿线七个白垩纪火山大厦的地壳样本及其相关基质。回收的两种最丰富的基底岩性是石灰岩（主要是前礁斜坡沉积物）和火山角砾岩，主要由磷化碳酸盐基质中分化的碱性玄武岩和夏威夷岩碎屑组成。这些海山斜坡上的质量浪费程度与地壳的厚度成反比。石灰岩基底上的地壳通常很薄。远离活跃的物质消耗过程区域和大型环礁，地壳最大厚度可能达到 10 厘米。马绍尔群岛地壳中的主要结晶相是 δ-MnO2（蛭石）。高浓度的钴、铂和铑强烈表明马绍尔群岛地壳是这些重要金属的可行来源。大多数地壳中的许多金属和稀土元素在精细尺度上变化很大，从而反映了地壳中不同主矿物相的丰度以及海水成分随时间的变化。高浓度的钴、镍、钛、锌、铅、铈和铂是由于它们在铁和锰相中的取代及其氧化电位的组合而产生的。
Ferromanganese crusts cover most hard substrates on seafloor edifices in the central Pacific basin. Crust samples and their associated substrates from seven volcanic edifices of Cretaceous age along the Ratak chain of the Marshall Islands are discussed. The two most abundant substrate lithologies recovered were limestone, dominantly fore-reef slope deposits, and volcanic breccia composed primarily of differentiated alkalic basalt and hawaiite clasts in a phosphatized carbonate matrix. The degree of mass wasting on the slopes of these seamounts is inversely correlated with the thickness of crusts. Crusts are generally thin on limestone substrate. Away from areas of active mass-wasting processes, and large atolls, crusts may be as thick as 10 cm maximum.The dominant crystalline phase in the Marshall Islands crusts is δ-MnO2(vernadite). High concentrations of cobalt, platinum and rhodium strongly suggest that the Marshall Islands crusts are a viable source for these important metals. Many metals and the rare earth elements vary significantly on a fine scale through most crusts, thus reflecting the abundances of different host mineral phases in the crusts and changes in seawater composition with time. High concentrations of cobalt, nickel, titanium, zinc, lead, cerium and platinum result from a combination of their substitution in the iron and manganese phases and their oxidation potential.