Sr isotope ratios identify origins of detrital materials in ferromanganese crusts: implication for tectonic and climatic impacts to submarine environment
Sr isotope ratios identify origins of detrital materials in ferromanganese crusts: implication for tectonic and climatic impacts to submarine environment
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发表时间：
2018-03
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通讯作者：
K. Azami;N. Hirano;J. Kimura
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作者：
K. Azami;N. Hirano;J. Kimura
铁锰结壳是在海底环境中通过化学沉淀形成的。结壳主要由铁锰氧化物和少量碎屑物质组成。由于铁锰氧化物从周围海水中吸收了多种元素，铁锰结壳中的Ns和Os同位素比值反映了降水时海水的同位素比值。因此，海洋同位素化学的时间变化是连续记录的，海洋同位素地层学适用于铁锰结壳的定年。未淋溶铁锰结壳中Sr/Sr同位素比值显示了现代海水的共同值，这是由于铁锰结壳中松散吸附的Sr与环境海水中的Sr进行了低温交换所致。因此，Sr同位素比值不适合定年。或者，由于某些碎屑物质具有独特的Sr同位素比，因此可以通过检查Sr同位素比来确定铁锰结壳中碎屑物质的来源。
Ferromanganese (Fe-Mn) crusts form by chemical precipitation in submarine environments. The crusts are composed of mainly Fe-Mn oxides with subordinate amount of detrital materials. Because Fe-Mn oxides absorb various elements from the surrounding seawater, Ns ad Os isotope ratios in the Fe-Mn crusts reflect those of seawater at the time of precipitation. Therefore, temporal changes in the marine isotope chemistry are recorded continuously and the marine isotope stratigraphy is applicable for dating of the Fe-Mn crusts. In contrast, Sr isotope ratios given by Sr/Sr in the unleached Fe-Mn crusts show a common value of the modern seawater due to low temperature exchange of the loosely absorbed Sr in the Fe-Mn crusts with that in the ambient seawater. Therefore, Sr isotope ratios are not suitable for dating. Alternatively, it is possible to identify the sources of detrital materials in the Fe-Mn crusts by examining Sr isotope ratios owing to the unique Sr isotope ratios of some detrital materials.