| 黄土高原黄土和太平洋沉积物 Nd，Sr 同位素变化的比较 |
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| 引用本文：杨杰东,陈骏,张兆峰,季峻峰,陈旸3）.2005.黄土高原黄土和太平洋沉积物 Nd，Sr 同位素变化的比较[J].地球学报,26(z1):192-194. |
| DOI：10.3975/cagsb.2005.s1.61 |
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| 中文摘要:东亚季风环流引起的风尘物质的搬运和堆积，形成了我国的黄土高原。最近几年发表了一些对太平洋沉积物 Nd和 Sr同位素的研究结果(Asahara,1999；Asahara 等，1995；Pettke 等，2000)。由于亚洲大陆是太平洋沉积物中风尘物质的主要来源之一，所以将黄土高原研究结果和太平洋沉积物的研究结果相比较，可以得出一些有益的结论。探讨黄土的源区，采用全岩样品进行 Sr 同位素研究不适合。对黄土样品进行了一系列酸淋洗实验（盛雪芬等，2000；Yang 等，200结果证明，选用弱醋酸淋洗，可以有效地去除黄土和古土壤中的方解石，而对白云石、粘土矿物和长石等结构的破坏程度可以忽略。本次研究的灵台剖面位于黄土土高原中部甘肃省平凉地区灵台县以南约13 km 的五星塬任家坡村，它是迄今为止在黄土高原发现的厚度最大的记录最完整的风尘堆积序列之一，其最早时代可达7.8 Ma B P。灵台剖面古土壤酸不溶物的87Sr/86Sr一般高于黄土的87Sr/86Sr。此次测试的黄土、古土壤和红粘土样品分粒级实验（杨杰东等，2005）显示，小于2μm的细颗粒部分具有最高的87Sr/86Sr，而其他颗粒部分的87Sr/86Sr均较低。因此，黄土高原剖面的87Sr/86Sr与小于2μm颗粒部分的比例，或与粘土矿物的含量有关，因为在小于m的细颗粒部分中主要是粘土矿物（图。 |
| 中文关键词:钕和锶同位素 风尘沉积 黄土高原 |
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| A Comparison of Variations in Nd and Sr Isotopic Compositions between the Loess Plateau and the Pacific Sediments |
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| Abstract:143Nd/144Nd and 87/Sr/86Sr rations of acid-washed residues of red clay and overlying loess-paleosols from the Lingtai profile in the loess plateau of China were determined. Sediments in central North Pacific Ocean have different fluctuations fo 87Sr/86Sr ratios from the Lingtai profile over the last 7.0 Ma. Nevertheless, fluctuations of ENd(0) in the Lingtai Profile from 7.0 Ma B P to the present are very similar to those of central North Pacific Ocean, which reflects the loess of the less plateau in China and sediments of central North Pacific Ocean are derived from the same source regions, and the source regions have been basically unchnged since 7.0 Ma B P. Red clay and the overlying loess-paleosol have very identical ENd (0). It can be inferred that both the red clay in the Loess Plateau and the overlying loess-paleoaols are probably of eolian origin and have the same source region. The phenomenon that most of the residues of red clay have higher 87Sr/86Sr ratios than the overlying loess-paleosols implies a climate of relatively high tempera ture and strong rainfall during the formaion of red clay. |
| keywords:Nd and Sr isotopes colian deposits loess plateau |
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