Travertine in South Bank of Dogai Coring, Tibet: Geochemical characteristics and potash geological significance
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摘要: 西藏多格错仁南岸地区发育有一系列正在沉积的钙华丘和盐泉，泉水具有较高的含钾异常，属于含钾溶滤卤水，因此确定泉水中的矿物质来源成为找钾的关键问题，研究钙华的地球化学特征和成因机制则有助于解决这一问题。区内钙华有原地钙华和碎屑钙华两种类型，且明显富集K、Fe等元素，具有明显的轻稀土富集特征。不同泉眼周围的钙华样品的稀土分配模式基本相同，表明区内钙华的钙物质具有同一来源层位。经过将钙华与区内主要地层的稀土元素特征进行比对，发现这些钙华和索瓦组具有明显的亲缘关系，针对两者的相关性分析也再次表明钙华和索瓦组的亲缘特征。在此基础上，结合区内古地理和古气候资料，认为索瓦组具有较好的找钾潜力。此外，盐泉和钙华的碳、氢、氧同位素数据说明，盐泉的水物质属于大气降水，形成钙华的CO2则具有深部来源特征，研究区的钙华属热成因钙华。Abstract: There are a series of depositing travertine domes and salt springs in South Bank of Dogai Coring of Tibet. With results of chemical composition of springs, we found that these springs have a high K concentration and belong tolixiviation brine. Thus, determining the source of K is a very important question. The research on travertine will help us resolve this Problem. Travertine in this area were composed of autochthonous travertine and clastic travertine,and have a high K ,Fe and light REE concentration. REE distribution patterns of different springs have the same trend and show that mineral substance of springs water come from the same stratigraphic position. With a REE comparison of travertine and major strata, we confirm that travertine and Suowa Formation have obvious genetic relationship. This result is consistent with correlation analysis for travertine and Suowa Formation. Combined paleographic and paleoclimatic data, we think that Suowa Formation has an exploration potential of potash. In addition, δD, δ18O and δ13C of salt springs and travertine indicate that H2O of springs come from atmospheric precipitation and CO2 of travertine has a characteristic of lithosphere deep source. Also, travertine in this area is thermogene travertine.
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Key words:
- travertine /
- Dogai Coring /
- REE /
- potash
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