临夏州供水保障工程CSAMT数据解译有效性分析

Validity Analysis of CSAMT Data Interpretation for Linxia Water Supply Security Project

研究区位于西秦岭北部褶皱带,分布地层均为老地层,岩性整体电阻率值较大,呈明显的团块状稳定电阻率异常。根据物性分析,各岩性存在明显的电性差异,电阻率特征整体变化趋势为:ρ灰岩>ρ砂板岩>ρ砂岩>ρ长石石英砂岩>ρ泥质砂岩>ρ泥质粉砂岩>ρ泥岩。本文通过CSAMT测量,圈定4个明显的电性分区,均由高电阻率岩性引起;推断有3条断裂构造,根据野外实地地质资料查证,该3条断裂构造与实地断层相对应,说明物探CSAMT数据解译对该区域具有一定的有效性。

The study area is located in the fold belt of the northern part of West Qin Mountains.The distribution strata are all old strata.The overall resistivity of the lithology is large and shows obvious lumpy stable resistivity anomaly.According to the analysis of physical properties,there are obvious electrical differences in each lithology,and the overall variation trend of resistivity characteristics is:plimestone>psandstone>psandstone>pfeldspar quartz sandstone>pargillaceous sandstone>pargillaceous silstone>pmudstone.By CSAMT survey,four distinct electrical zones are delineated,which are all caused by high resistivity lithology,and three fault structures are inferred,which are verified by field geological data,the 3 fault structures correspond to the faults in situ,which shows that the interpretation of geophysical CSAMT data is effective in this area.