西太平洋富钴结壳形成年代的探讨

Rasearch on the Age of Cobalt-Rich Crusts in Western Pacific

本文为我国首次采用生物地层法探讨西太平洋麦哲伦海山区富钴结壳的生长年代。生物地层法计年的样品,取自厚度为97mm结壳的自顶至底的20mm、35mm、58mm、62mm及75mm处。结果表明,在62mm处发现了具地层时代鉴定意义的始新世早期Discoaster multiradiatus、Discoaster elegans、Discoaster barbadiensis、Tribrachiatus orthostylus等钙质微体化石印痕,从而推断该区富钴结壳的生长年代可追朔至始新世或更老年代。此外,作者亦将此结果与中太平洋生物地层法的计年结果进行了对比并讨论了其地质意义。

The age of cobalt-rich crusts from the Magellan Seamount in the western Pacific has been first approached by using the method of biostratigraphic dating. The subsamples collected from the positions at 20, 35, 58, 62 and 75 mm from top to bottom in a crust 97 mm thick were studied. Special calcareous foraminiferal prints of Discoaster multiradiatus, Discoaster elegans, Discoaster barbadiensis, Tribrachiatus arthostylus etc. of the early Eocene were found at 62 mm. It is thus concluded that the age of cobalt-rich crusts in this area can be traced back into the Eocene or even earlier. In addition, the authors have made a correlation of the present dating with that of crusts from the Central Pacific and present a discussion on its geological significance.