| 引用本文: | 刘溪溪,岳鑫,于小亮,马喆,路亮,张晓冬,马宗德.柴达木盆地西北缘昆特依凹陷的双层钾盐成矿模式特征及成因.湖泊科学,2020,32(1):246-258. DOI:10.18307/2020.0123 |
| LIU Xixi,YUE Xin,YU Xiaoliang,MA Zhe,LU Liang,ZHANG Xiaodong,MA Zongde.Characteristics and genesis of the double potash layer metallogenetic model of Kunteyi Depression in the northwest margin of Qaidam Basin. J. Lake Sci.2020,32(1):246-258. DOI:10.18307/2020.0123 |
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| 柴达木盆地西北缘昆特依凹陷的双层钾盐成矿模式特征及成因 |
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刘溪溪1,2, 岳鑫1,2, 于小亮3, 马喆4, 路亮1, 张晓冬1,2, 马宗德1,2
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1.青海省柴达木综合地质矿产勘查院, 格尔木 816000;2.青海省柴达木盆地盐湖资源勘探研究重点实验室, 格尔木 816000;3.青海省地质调查局, 西宁 810000;4.青海省盐湖地质与环境重点实验室, 西宁 810000
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| 摘要: |
| 柴达木盆地是我国和世界重要的钾盐产地，目前对地表浅层盐湖钾盐研究颇多，但对深部碎屑孔隙钾盐研究较少.本文以昆特依凹陷为例，总结柴达木盆地钾盐成矿的时空变化规律，通过对该区地质、水文、古环境及卤水储层特征等分析建立“双层钾盐”成矿模式：上层为赋存在Qp2-h盐湖相化学盐类晶体裂隙间的晶间卤水，下层是Qp1冲洪积相砂砾孔隙卤水.采用聚类分析、特征系数、介稳相图、piper三线图及氢氧同位素等数理、地球化学手段分析上、下层卤水离子含量，探讨“双层钾盐”模式成因和上、下层卤水的内在联系.研究认为，昆特依凹陷内“双层钾盐”赋存卤水均为陆相沉积环境中的盐岩溶滤水，其中上层晶间卤水更多表现为盐岩溶解，但也不乏溶滤作用，下层砂砾孔隙卤水则着重表现为石盐的溶解；上层晶间卤水表现出下层砂砾孔隙卤水深度演化的特征，下层砂砾孔隙卤水具有对深部古盐岩层及上层晶间层的继承性；昆特依凹陷周边的新近纪背斜构造区油田水在成因上也与“双层钾盐”卤水密切相关. |
| 关键词: 柴达木盆地 钾盐矿床 晶间卤水 砂砾孔隙卤水 水化学特征 昆特依凹陷 |
| DOI：10.18307/2020.0123 |
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| 基金项目:中央地质勘查基金项目（2013630003）、青海省地质勘查基金项目和青海省自然科学基金项目（2019-ZJ-911）联合资助. |
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| Characteristics and genesis of the double potash layer metallogenetic model of Kunteyi Depression in the northwest margin of Qaidam Basin |
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LIU Xixi1,2, YUE Xin1,2, YU Xiaoliang3, MA Zhe4, LU Liang1, ZHANG Xiaodong1,2, MA Zongde1,2
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1.Qaidam Integrated Geological Exploration Institute of Qinghai Province, Golmud 816000, P. R. China;2.Key Laboratory of Salt Lake Resources Exploration in Qaidam Basin, Qinghai Province, Golmud 816000, P. R. China;3.Geology Survey Bureau of Qinghai Province, Xining 810000, P. R. China;4.Key Laboratory of Salt Lake Geology and Environment of Qinghai Province, Xining 810000, P. R. China
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| Abstract: |
| The Qaidam Basin represents an important provenance for potassium salt in China and in the world. So far, studies have mostly focused on potassium salt in shallow subsurface salt lakes, whereas little has been reported about potassium salt in deep clastic pores. In the present study, the spatial-temporal evolutions involved in the metallogenesis of potassium salt in the Qaidam Basin are summarized within the context of the Kunteyi Sag as an example. A "double-layered potassium salt" model consisting of intercrystalline brine in the Qp2-h salt-lake facies chemical salt crystal fissures underlain by the Qp1 alluvial-proluvial gravel pore brine is established after investigating the local geology, paleo-environment, and brine reservoir distribution in the study area. The genesis of this "double-layered potassium salt" model and the internal connections between the overlying and underlying brine layers are explored by comparing the ionic contents in these layers through mathematical and geochemical approaches such as cluster analysis, characteristic coefficient, piper trilinear nomograph, and hydrogen and oxygen isotopes. The results indicate that within the Qaidam Basin, the brine in the "double-layered potassium salt" unexceptionally comprises salt rock lixiviation water from a continental sedimentary background. The overlying intercrystalline brine suggests more of salt rock dissolution, although lixiviation may have also played a role; the underlying gravel pore brine points more toward rock salt dissolution. The overlying intercrystalline brine seems to originate from the deep evolution of the underlying gravel pore brine, whereas the underlying gravel pore brine appears to be successive from the deep paleo-salt rock layers and the overlying intercrystalline layer. The oilfield water in the Neogene anticlinal structures surrounding the Kunteyi Sag also shows a close genetic connection with the "double-layered potassium salt" brine. |
| Key words: Qaidam Basin potash deposit intercrystalline brine gravel pores brine hydrochemical characteristics Kunteyi Depression |
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