Osmium isotope stratigraphy of a marine ferromanganese crust
Osmium isotope stratigraphy of a marine ferromanganese crust
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DOI：
10.1016/j.epsl.2005.07.016
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发表时间：
2005-09-30
影响因子：
5.3
通讯作者：
Halliday, AN
中科院分区：
文献类型：
--
作者：
Klemm, V;Levasseur, S;Halliday, AN
铁锰结壳是海洋环流和大陆风化长期变化的记录。然而，校准他们的年龄之前，10马已完全基于经验的增长率模型，使用钴浓度，这本身就有很大的不确定性，并未能检测到间断和侵蚀事件。我们提出了一种新的方法来测定这些结壳的锇（Os）同位素记录，并将其与过去80 Ma的海洋Os同位素演化相匹配。来自中太平洋的特征良好的地壳CD 29 -2被认为定义了50 Ma以来的古海洋学变化记录。以前的增长率估计的基础上的Co方法是一致的新的Os同位素地层学，但约会是非常不准确的，由于长的间断，现在可以检测到。新的年代学表明，它实际上在晚白垩世70 Ma之前开始生长，并在13.5至47 Ma之间停止生长或被侵蚀。有了这项新技术，现在可以充分利用铁锰结壳中储存的海洋学和气候记录的潜力。(c)2005 Elsevier B. V.保留所有权利。
Ferromanganese crusts provide records of long term change in ocean circulation and continental weathering. However, calibrating their age prior to 10 Ma has been entirely based on empirical growth rate models using Co concentrations, which have inherently large uncertainties and fail to detect hiatuses and erosional events. We present a new method for dating these crusts by measuring their osmium (Os) isotope record and matching it to the well-known marine Os isotope evolution of the past 80 Ma. The well-characterised crust CD29-2 from the central Pacific, was believed to define a record of paleooceanographic change from 50 Ma. Previous growth rate estimates based on the Co method are consistent with the new Os isotope stratigraphy but the dating was grossly inaccurate due to long hiatuses that are now detectable. The new chronology shows that it in fact started growing prior to 70 Ma in the late Cretaceous and stopped growing or was eroded between 13.5 and 47 Ma. With this new technique it is now possible to exploit the full potential of the oceanographic and climatic records stored in Fe-Mn crusts. (c) 2005 Elsevier B.V. All rights reserved.