西藏捌仟错深部卤水层电性结构特征及成因分析  

Electrical Structure Characteristics and Genesis Analysis of Deep Brine Layer in Qianqiancuo,Tibet

作　　者：李卫强 于常青 邹长春[1] 张平川[1,2] 杨凤清 柳胜春 汪洋 LI Wei-qiang;YU Chang-qing;ZOU Chang-chun;ZHANG Ping-chuan;YANG Feng-qing;LIU Sheng-chun;WANG Yang(School of Land and Resources Engineering,China University of Geosciences(Beijing),Beijing 100083,China;Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Tibet Ali Liyuan Mining Development Co.,Ltd.,Lhasa 859499,China;East China 814 Geophysical Prospecting Co.,Ltd.,Nanjing 210014,China)

机构地区：[1]中国地质大学(北京)地球物理与信息技术学院,北京100083 [2]中国地质科学院地质研究所,北京100037 [3]西藏阿里锂源矿业开发有限公司,拉萨859499 [4]江苏华东八一四地球物理勘查有限公司,南京210014

出　　处：《科学技术与工程》2024年第22期9273-9281,共9页Science Technology and Engineering

基　　金：国家自然科学基金(41941016);国家自然科学基金国际(地区)合作与交流项目(41374128)。

摘　　要：为探测西藏捌仟错深部是否存在大面积的“卤源”,理清盐湖区深部卤水的分布特征、控制因素及物质来源,开展了1∶15000音频大地电磁探测,其中包含水域物理点12个,获得了深部纵向上“高-低-高-低”4层电阻率模型。结果显示在盐湖区南部发育一组正断裂,这组断裂既可作为储水构造也可作为导水通道,形成导卤断裂带。在断裂露头处的含卤喷泉印证了本文观点。通过整理分析9口钻井资料,圈定了盐湖下方浅部卤水层的范围,并且发现该范围与第一套连续性较好的低电阻率层对应,推测该层为富水有利层。最后,通过分析卤水的化学元素成分及含量,结合新近系岩浆活动及构造背景,认为捌仟错卤水物质来源与火山活动相关。研究结果表明了音频大地测深是研究深层卤水的重要方法,证明了水域音频大地电磁(audio magnetotelluric,AMT)的可行性和有效性。To detect the presence of a large‘brine source’in the deeper parts of Tibet's Baqiancuo Salt Lake area,and to understand its distribution characteristics,control factors,and material sources,1∶15000 AMT(audio magnetotelluric)detection was conducted.This involved 12 physical points in the water area,resulting in a four-layer resistivity model showing a‘high-low-high-low’pattern in the deep longitudinal direction.The results suggest that a group of normal faults exist in the southern region of the Salt Lake area,which act as both water storage and conduction channels,forming a brine conduction fault zone.The finding is compatible with the halogenated fountain at the fracture outcrop.By analyzing data from 9 wells,the range of shallow brine layer below the Salt Lake was identified,which corresponds to the first set of low resistivity layers with good continuity.These results suggest that the layer is a water-rich favorable layer.Finally,after analyzing the chemical composition and content of the brine,combined with Neogene magmatic activity and tectonic background,it is generally accepted that the source of the brine is related to volcanic activity.This study highlights the importance of using audio geodetic sounding as an effective method to study deep brine,and proves the feasibility and effectiveness of AMT in water exploration.

关 键 词：捌千错盐湖 音频大地电磁 电阻率模型 电性结构特征 物质起源 

分 类 号：P319.1[天文地球—固体地球物理学]