AMT法在塔里木盆地吐格尔明背斜及含铀地层识别中的应用

塔里木盆地吐格尔明背斜与铀成矿关系密切,铀矿化赋存于中侏罗统克孜勒努尔组(J2k),随着研究区找矿深度的加大,找矿靶区的选择成为难点。通过音频大地电磁测量(AMT)识别吐格尔明背斜及中侏罗统克孜勒努尔组的发育特征十分必要。该文总结了研究区各地质(层)体的岩石电阻率特征,设计了研究区正演模型,并通过各初始模型的反演对比,优选了反演参数。通过对实测AMT资料电性特征分析,认为研究区自西向东,吐格尔明背斜形态由紧闭逐渐变得宽缓,核部轴面近于直立。中侏罗统克孜勒努尔组(J2k)北厚南薄,西部埋深小、厚度大,东部埋深大、厚度小,找矿重点应该放在研究区的中西部,为下一步铀矿勘查工作提供了地球物理基础。

Identification of Tugerming Anticline and uranium-bearing strata by AMT in Tarim Basin

Uranium mineralization in the study area is closely related to the tugerming anticline. Uranium mineralization occurs in the Middle Jurassic kizilnur formation (J₂K). With the increase of prospecting depth in the study area, the selection of prospecting target area becomes difficult. It is necessary to identify the development characteristics of tugerming anticline and kizilenur formation of Middle Jurassic by audio Magnetotelluric Survey (AMT). This paper summarizes the rock resistivity characteristics of each geological body in the study area, designs the forward model of the study area, and optimizes the inversion parameters through the inversion comparison of each initial model. Based on the analysis of the electrical characteristics of AMT data, it is considered that from west to East, the form of tugerming anticline gradually becomes wide and gentle from close to close, and the axial plane of the core is nearly vertical. The Middle Jurassic kizilnur formation (J₂K) is thick in the north and thin in the south, with small buried depth and thickness in the West and large buried depth and thickness in the East. The prospecting focus should be placed in the middle and west of the study area, which provides the geophysical basis for the next mineral exploration work.