柴达木盆地西部鄂博梁Ⅱ号构造深层卤水储层特征与锂硼资源富集成因

Characteristics of Deep Brine Reservoirs and Origin of Enrichment of Lithium and Boron Resources in the Eboliang Ⅱ Structure in the Western Qaidam Basin

中文关键词:  深层卤水  Li、B资源  富集成因  储层特征  鄂博梁Ⅱ号构造  柴达木盆地

英文关键词:Deep brine  Li and B resources  Origin  Reservoir characteristics  The Eboliang No. II structure  Qaidam Basin

中文摘要:

      鄂博梁Ⅱ号构造是柴达木盆地西部鄂博梁Ⅰ-Ⅲ号褶皱带中的一个局部构造,在古新世—上新世以来主要为河流泛滥平原相、滨浅湖相和深湖相构造环境,在“高山深盆”的构造环境下,接受了大量造山带物源碎屑补给并赋存卤水矿床。通过对钻孔岩性、孔隙度、给水度、地球物理测井等数据进行分析,总结下油砂山组下部和干柴沟组地层是区内相对较好的深层卤水赋存层位,可作为深层卤水的重点探矿层位进一步勘查。同时,鄂博梁Ⅱ号构造钻孔深层卤水化学组成及特征系数分析结果显示,该水体为低矿化度(平均值为73.00 g/L)、Na⁺、Cl-为主的卤水,其中Li、B等元素含量达到边界品位以上,Br、I元素含量也达到或接近综合利用标准,具有较好的深层卤水找矿前景；卤水的成因为柴达木盆地周缘中新生代以来深部火山热泉补给、造山带火山岩物质风化和溶滤盐岩富集成矿。

英文摘要:

      The Eboliang No. II structure is a local structure in the Eboliang No. I-III fold belt in the western Qaidam Basin. Since the Paleocene-Pliocene, it is mainly composed of river flood plain phase, shallow lake facies and deep lake facies, and has received a large number of resource elements and clastic sediments from volcanic rocks of orogenic belts and occurred brine deposits in strata under the tectonic environment of “high mountains and deep basins”. On the basis of the analysis of drilling lithology, porosity, water yield and geophysical logging, it is considered that the lower part of the Lower Youshashan Formation and the Ganchaigou Formation are relatively good deep brine occurrence layers in the area. The key prospecting horizons of brine should be further explored in the present or future works. At the same time, the results of the chemical composition and characteristic coefficients of the deep brine at different depths from drilling cores in the Eboliang No. Ⅱ structure show that the resource elements such as Li and B concentrations in the brines reach above the cut-off grade, and the Br and I concentrations also reach or approach the comprehensive utilization standard. It has good prospecting potential of deep brine in this region. The origin is related to the supply of deep volcanic hot springs and the weathering of volcanic rock from orogenic belt since the Mesozoic-Cenozoic, and leaching of halite rock from strata in the western Qaidam Basin.