| 青海囊谦高浓度盐泉硼同位素地球化学特征及其地质意义研究 |
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| 关键词:salt spring boron isotope Nangqian Basin hydrochemistry geological significance |
| 基金项目:国家“973”前期项目(编号: 2012CB426501);青海省应用基础研究计划(编号: 2014-ZJ-702; 2012-Z-702) |
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| Boron Isotope Geochemical Characteristics and Its Geological Significances of High Salinity Salt Springs in Nangqian Basin, Qinghai Province, China |
| Based on element composition and stable isotope analysis of high salinity salt springs in the Nangqian basin, the paper mainly studies sources of salt materials and their formation conditions of the springs. The results show that the average salinity of the springs in the Nangqian Basin is 254.6 g/L, with a higher salinity in the east than in the west of the basin. The hydrochemical types of the springs are all sulfate type with neutral pH value. Chemical elements in the springs can be divided into three groups: Na+-Cl–-K+-Br-, B3+-Li+-SO2– 4-HCO– 3 and Ca2+-Mg2+. High salinity and element geochemical characteristics indicate that salt strata are under the Nangqian Basin, which can provide rich salt materials for the springs. We concluded that the salts in the springs come mainly from dissolution of underground halite and a small amount of limestone and gypsum rock. The boron isotope δ11B values in the springs range from 3.55‰ to 35.49‰ with a gradual decrease from northwest to southeast, which shows that the underground salt strata had formed in continental environments combining with the data of Br content. There is an inverse relationship between δ11B values and boron content in springs with a two-end-members: high boron content versus low δ11B value and low boron content versus high δ11B value, meanwhile, another inverse relationship between δ11B and pH values was also discovered. Regional geological studies lead to the conclusion that the large amount of igneous rocks exposed in the Duolunduo area may be an important source of the boron in the springs. According to the comprehensive and comparative study, the following four factors are essential conditions for salt-spring formation in the Nangqian Basin: 1) the saliferous strata are the source of salt materials in the springs; 2) stable rainfall offers sustained water source for the spring; 3) widely distributed faults supply channels for groundwater migration; 4) large topographic altitude differences provide a stronger hydraulic gradient for groundwater flow. |
| HAN Feng-qing,CHEN Yan-jiao,HAN Ji-long,HAN Wen-xia,MA Yun-qi,NIAN Xiu-qing,YANG Xiu-meng.2016.Boron Isotope Geochemical Characteristics and Its Geological Significances of High Salinity Salt Springs in Nangqian Basin, Qinghai Province, China[J].Acta Geoscientica Sinica,37(6):723-732. |
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