ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    音频大地电磁法探测滇中陆良盆地及邻区的地质结构特征

    Geological Structure Characteristics of the Luliang Basin and Adjacent Areas in Central Yunnan Detected by Audio Magnetotelluric Method

    • 摘要: 陆良盆地是云南面积最大的新生代(新近纪)盆地,构造活动活跃。采用音频大地电磁测深对盆地及邻区进行探测分析,有效确定了研究区地下的电性、地质及结构特征。判识断裂20(F1-F20)条,其中曲靖–陆良断裂带(F15-F18)对盆地形态特征影响极大;在盆地地段,判识7条隐伏断裂,并可能在第四纪期间仍具有一定活动性,主边界断裂为盆地东缘断裂,具有显著的正断层活动特征。盆地充填地层从地表到深部可依次划分为第四系和新近系茨营组(N2c1-4 )一段至四段共5层,在剖面上显示其深度超过1000 m,整个盆地中心深度超过1600 m。确定了盆地结构形态特征,证实了陆良盆地为新生代近SN向的箕状断陷盆地,基底为泥盆系、石炭系和二叠系。实例表明音频大地电磁测深对盆地探测是有效的地球物理方法。

       

      Abstract: The Luliang Basin with active tectonics is the largest Cenozoic (Neogene) basin in Yunnan Province.The audio magnetotelluric sounding was effectively used to detect and analyze the underground spatial electrical properties and structural characteristics of the basin and its adjacent areas.Twenty faults (F1-F20) were identified, including the Qujing-Luliang fault belt (F15-F18) that has a great impact on the basin morphology;seven concealed faults in the basin section that probably continue active during the Quaternary period;and the main boundary faults at the eastern edge of the basin characterized by significant normal fault movement.The profile shows that its depth is more than 1000 m, and the depth of the whole basin center is more than 1600 m. The strata in the basin from surface to deep has been divided into five layers comprised of the Quaternary and the first to the fourth Members of Neogene Ciying Formation (N2c1-4). The structural and morphological characteristics of the basin suggest that the Luliang basin is a Cenozoic SW trending dustpan fault basin, with Devonian, Carboniferous and Permian basement.The example shows that audio magnetotelluric sounding is an effective geophysical method for basin exploration.

       

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