Os isotopic compositions of a cobalt-rich ferromanganese crust profile in Central Pacific
187Os/188Os ratios in all sub-layers of the Co-rich ferromanganese crust MP5D17 from Line Seamount in Central Pacific have been systematically determined. The 187Os/188Os values in this crust are highly variable, ranging from 0.4262 to 1.0155. From the bottom to the top, the osmium isotopic ratios of the crust display a regular variation trend, which correlates well with its changes in structure and texture in the vertical profile. In comparison with the evolution curve of Os isotopic composition in seawater over the past 80 Ma, a similar evolution tendency can be found with respect to the Os isotopic composition of the crust in this study. It is preliminarily concluded that the crust MP5D17 began to grow at about 72 Ma, and underwent three growth hiatuses, corresponding to the geological ages of 64, 53 and 37 Ma, respectively.
作 者： 作者单位： 刊 名： 科学通报（英文版） SCI 英文刊名： CHINESE SCIENCE BULLETIN 年，卷(期)： 2005 50(18) 分类号： P7 关键词： Co-rich ferromanganese crust crust profile osmium isotopic composition Central Pacific