柴达木盆地昆特依盐湖含杂卤石地层高分辨率矿物学研究  

High-resolution mineralogical investigations on polyhalite-bearing strata in the Kunteyi salt lake,Qaidam basin

作　　者：李俊 张西营[1,2,3] 张星 胡明月 孙东阳[4] 赵令浩 苗卫良[1,2] 李雯霞[1,2,3] 李永寿 唐启亮[1,2] 袁小龙 都永生[1,2] LI Jun;ZHANG Xiying;ZHANG Xing;HU Mingyue;SUN Dongyang;ZHAO Linghao;MIAO Weiliang;LI Wenxia;LI Yongshou;TANG Qiliang;YUAN Xiaolong;DU Yongsheng(Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining,Qinghai 810008,China;Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes,Xining,Qinghai 810008,China;University of Chinese Academy of Sciences,Beijing 100049,China;National Research Center for Geoanalysis,Beijing 100037,China)

机构地区：[1]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,青海西宁810008 [2]青海省盐湖地质与环境重点实验室,青海西宁810008 [3]中国科学院大学,北京100049 [4]国家地质实验测试中心,北京100037

出　　处：《地质学报》2021年第7期2138-2149,共12页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号41672087,41402082);第二次青藏高原综合科学考察研究(编号2019QZKK0805);中国科学院“西部青年学者”项目(编号Y910031013)联合资助的成果。

摘　　要：柴达木盆地昆特依盐湖杂卤石资源丰富,是开展现代内陆盐湖杂卤石成因机制研究的良好载体。精细刻画沉积特征对阐释沉积矿床成因具有重要作用。本研究以昆特依盐湖大盐滩矿区ZK3608钻孔岩芯14.08-25.48 m段碎屑-杂卤石沉积韵律为研究对象,开展高分辨率矿物学研究,结合石盐流体包裹体化学组成和石盐中微量元素分析,尝试从高分辨率沉积学和矿物学的角度探讨杂卤石的成因。研究结果显示,石盐层产出的杂卤石含量低但分布范围广,为原生矿物;碎屑层中的杂卤石主要为次生矿物。石盐层与碎屑层之间存在一个过渡层位,该层位的杂卤石高度富集且矿物组成复杂,推测是由于原生与准同生杂卤石短时间内先后形成导致的。结合石盐流体包裹体化学组成所代表的古卤水变化特征分析表明,Ca-Cl型深部油田卤水的补给对研究区不同时期杂卤石的形成有重要影响。地球化学特征综合分析指示,石盐层的原生杂卤石由富钾镁的浓缩卤水与Ca-Cl型深部油田卤水混合直接生成;而过渡层位的杂卤石受到气候变化与Ca-Cl型深部油田卤水补给的共同作用。Kunteyi Salt Lake in the Qaidam Basin is rich in polyhalite resources,which are a good carrier for studying the genetic mechanism of polyhalite in modern inland salt lakes.Meticulous description of sedimentary characteristics plays an important role in explaining the genesis of sedimentary deposits.In this study,a high-resolution mineralogical study was carried out on the clastic-polyhalite sedimentary cycle of ZK3608 core section from 14.08 m to 25.48 m in the Dayantan Playa of the Kunteyi Salt Lake.Combined with the chemical composition of fluid inclusions in halite and the analysis of trace elements in halite,the origin of polyhalite is inferred from the perspective of high-resolution sedimentology and mineralogy.The results show that the polyhalite produced by halite layer,though low in content,is widely distributed and is a primary mineral.The polyhalite in clastic layers is mainly a secondary mineral.There is a transitional horizon between halite and clastic layer,and the polyhalite in this horizon is highly enriched with a complex mineral composition,which is considered to have been caused by the formation of primary and penecontemporaneous polyhalite in a short time.This information,combined with the variation characteristics of ancient brine represented by the chemical composition of halite fluid inclusions,shows that the replenishment of Ca-Cl deep oil brine has an important impact on the formation of polyhalite in different periods in the study area.Comprehensive analysis of geochemical characteristics indicates that the primary polyhalite of halite layer is directly produced by mixing concentrated brine of salt lake with Ca-Cl deep brine oil brine.However,the polyhalite in the transitional stage of sedimentary facies is affected by climate change and brine replenishment in Ca-Cl deep oilbrine.

关 键 词：昆特依盐湖 杂卤石成因 高分辨率矿物学 赋存特征 石盐流体包裹体 元素地球化学 

分 类 号：P619.211[天文地球—矿床学]