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近年来,大地电磁(MT)在揭示壳幔电性结构、深部找矿和油气勘探等方面正发挥着举足轻重的作用。本文所研究的41°N88°E标准点位于塔里木盆地的东北部区域和天山板内造山带的南侧。通过采用RRI反演方法对不同模式的MT数据进行了反演研究,获得了研究区域内可靠的二维电性结构。结合区内地质和其它物探资料,探讨了该地区的地下电性结构变化特征及其地质意义。根据41°N88°E号标准点地区NS剖面和WE剖面的反演结果,该区域纵向上存在两个起伏较大的电性分界面;整个剖面可分为3个主电性层:第一电性层为表层低阻层;第二电性层为壳内高阻层,包括两个沿剖面不连续分布的区块,规模和埋深有很大差别,整体具有北薄南厚和东薄西厚的特征;第三电性层表现为中低阻特征,位于莫霍面以下。东部的却尔却克构造岩片下有一低阻区域,推测为软流圈隆起使塑性的软流圈物质上涌到较浅的位置从而形成了高导层。研究区莫霍面深度起伏较大,总体上呈现出北浅南深和东浅西深的趋势。其中库鲁克塔格断隆地区莫霍面深度较浅约为35km左右,带有上凸的趋势;孔雀河斜坡区莫霍面深度在50~55km,带有下凹形状。
In recent years, MT has played a decisive role in revealing the crust-mantle electrical structure, deep ore prospecting and oil and gas exploration. The 41 ° N88 ° E standard point studied in this paper is located in the northeastern part of the Tarim Basin and the southern side of the Tianshan intraplate orogenic belt. By using RRI inversion method, the MT data of different modes are inverted and the reliable two-dimensional electrical structure in the studied area is obtained. Combined with the geology and other geophysical data in the area, the variation characteristics of underground electrical structure and its geological significance are discussed. According to the inversion results of the NS section and the WE section at the standard point of 41 ° N88 ° E, two undulating electrical interfaces exist longitudinally in the region; the whole section can be divided into three main electrical layers: the first The electrical layer is a low-resistivity surface layer. The second electrical layer is a high-resistivity layer in the shell, and includes two blocks that are discontinuously distributed along the section. The size and depth of the second layer are greatly different. The third electrical layer is characterized by medium and low resistivity and is located below the Moho. There is a low resistivity region beneath the Turcot rock in the east, suggesting that asthenosphere uplifts the plastic asthenosphere up to a shallow position and thus forms a high-conductivity layer. The depth of the Moho in the study area is large and fluctuant, showing a trend of north shallow south and shallow east-west deep. The depth of the Moho in the Kuruktag fault area is about 35 km, with a convex upward trend. The Moho depth in the Peacock River slope area is between 50 and 55 km with a concave shape.