塔里木盆地库车坳陷古新统—始新统蒸发岩地球化学特征及成钾分析——以KL4井为例  

Geochemical characteristics and potash formation analysis of Paleocene-Eocene evaporites in Kuqa depression of Xinjiang:A case study of borehole KL4

作　　者：徐洋[1] 刘成林[1] 焦鹏程[1] 陈永志[1] 曹养同[1] 

机构地区：[1]中国地质科学院矿产资源研究所,北京100037

出　　处：《岩石矿物学杂志》2017年第5期755-764,共10页Acta Petrologica et Mineralogica

基　　金：国家"十二五"科技支撑课题(2011BAB06B06)~~

摘　　要：库车坳陷古新统—始新统发育巨厚的蒸发岩,尤其是盆地西部,出露多处盐矿点。本文主要研究了KL4钻孔古新统—始新统蒸发岩中钾盐矿物和含钾矿物特征,在此基础上分析了库车坳陷古新统—始新统蒸发岩地层中成钾趋势。研究发现,在含钾层段Ⅰ产出钾芒硝,层段Ⅱ产出原生钾石盐、钾石膏和含钾石盐石膏,说明古盐湖已经达到钾盐沉积阶段。钻孔化学组分分析结果显示,钻孔底部至顶部K^+浓度呈现不断富集的趋势,且最大值达到1.273%,结合离子含量、钾氯系数、镁氯系数、锂氯系数和锶钙系数等特征,进一步确定古盐湖演化过程中存在两次成钾浓缩趋势,认为含钾层段Ⅰ和Ⅱ具有成钾潜力,其中层段Ⅱ成钾潜力更大。Paleocene-Eocene thick evaporites are developed in Kuqa depression, especially in the western part, with many salt spots. In this paper, the authors studied potash minerals and potassium-bearing salt minerals of Paleocene-Eocene evaporites so as to analyze potash-forming trend of Paleocene-Eocene evaporites in Kuqa depression. Glaserite mineral exists in potash-forming layer sectionⅠ; original sylvine, potassium gypsum and potassium-bearing halite gypsum occur in potash-forming layer section Ⅱ, indicating that ancient salt lake had reached potash deposition phase. Borehole chemical composition analysis shows that, from borehole bottom to the top, the shallower the depth, the higher the K＋ concentration, with a maximum of 1.273%. In combination with characteristics of ions content, the potassium-to-chlorine ratio, the magnesium-to-chlorine ratio, the lithium-to-chlorine ratio and the strontium-to-calcium ratio, the authors determined two potash-forming trends during ancient salt lake evolution, and initially hold that potassium layer section Ⅰ and Ⅱ have the potential to form potash, with layer section Ⅱ having larger potential to form potash.

关 键 词：蒸发岩 矿物学 地球化学 古新统—始新统 成钾分析 库车坳陷 

分 类 号：P588.247[天文地球—岩石学] P595[天文地球—地质学]