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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The accretion rate of extraterrestrial ~3He based on oceanic ~(230)Th flux and the relation to Os isotope variation over the past 200,000 years in an Indian Ocean core
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The accretion rate of extraterrestrial ~3He based on oceanic ~(230)Th flux and the relation to Os isotope variation over the past 200,000 years in an Indian Ocean core

机译：印度洋中心近200，000年基于海洋〜（230）Th通量的外星〜3He的增生率及其与Os同位素变化的关系

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摘要

In the eastern equatorial Indian Ocean, the flux extraterrestrial ~3He, a proxy of interplanetary dust particles (IDPs), has been relatively constant over the past 200 ka. The flux is equal to (1.1 +- 0.4) * 10~(-12) cm~3 STP cm~(-2) ka~(-1), a value obtained using the xs~(230)Th profiling method. Variations in mass accumulation rates (MARs) derived assuming a constant extraterrestrial ~3He flux have a 40-ka periodicity similar to that observed in the #delta#~(18)O-derived MARs. This frequency is similar to that of the Earth's obliquity. Measured ~(187)Os/~(188)Os ratios are less radiogenic than present-day seawater (0.49-0.98), reflecting the mixing of Os derived from extraterrestrial, terrigenous and hydrogenous sources. When coupled with He data measured on the same samples, Os isotope data yield important information above the terrigenous component supplied to the eastern equatorial Indian Ocean. The amount of Os in the sample derived from the extraterrestrial component can be deduced with the help of the helium systematics. Once correcter for the extraterrestrial component of Os, Os, isotope signatures, in conjunction with the ~4He concentrations, suggest a supply of terrigenous material from Indonesian ultramafic and Himalayan crustal sources that clearly varies through time.
机译：在赤道东印度洋，过去200 ka以来，外星通量〜3He（行星际尘埃粒子（IDPs）的代名词）相对稳定。通量等于（1.1 +-0.4）* 10〜（-12）cm〜3 STP cm〜（-2）ka〜（-1），这是使用xs〜（230）Th轮廓分析方法获得的值。假设恒定的外星〜3He通量得出的质量累积速率（MARs）的变化具有40-ka周期性，与＃delta〜（18）O衍生的MARs相似。这个频率类似于地球倾角的频率。测得的〜（187）Os /〜（188）Os比率比当今的海水（0.49-0.98）的放射源少，反映了来自地外，陆源和氢源的Os的混合。结合在相同样品上测得的He数据，Os同位素数据可提供重要的信息，高于提供给赤道东部印度洋的陆源成分。可以借助氦系统来推导样品中来自地外成分的Os量。一旦校正了Os的地外成分，Os，同位素特征以及〜4He浓度，就表明印度尼西亚超镁铁质和喜马拉雅地壳来源的陆源物质供应随时间明显变化。

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