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

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 (N₂c^1-4). 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.