中亚造山带东段岩石圈电性结构特征及其构造涵义

中亚造山带东段内蒙古中部地区一直是地球内部动力学和全球变化研究的热点地区。鉴于该地区的构造在理解中亚造山带的形成过程中起着重要作用，因此对该地区构造的研究具有重要意义。本文收集了中亚造山带东段一条长364 km的大地电磁测深(MT)剖面数据，该剖面西北起于内蒙古东乌旗内的国境线附近，向东南延伸，穿过北部造山带、索伦缝合带、南部造山带，在内蒙古翁牛特旗以西约30 km附近终止。根据数据的分析结果，对该剖面进行了二维反演。结果表明，剖面区段内岩石圈电性结构沿南北方向上整体表现为横向分块的特征。其中，北部造山带整体上以低阻为主要特征；索伦缝合带是整个剖面电性特征从低阻到高阻的过渡区；南部造山带整体上以高阻为主要特征。北部造山带的低阻特征表明该区域是不稳定的，可能是由古亚洲洋闭合后残留洋壳或者软流圈上升流引起的。索伦缝合带的电性结构特征表明该区域可能在缝合之后还发生了新的构造事件。南部造山带的高阻特征表明该区域基底是稳定的、“冷”的，且流体含量很低，电性结构的几何特征反映了该区域增厚的岩石圈。剖面所经过区域的电性结构特征表明，在西伯利亚板块与华北板块碰撞缝合之后研究区内可能还发生了诸如软流圈流...

Lithospheric Electrical Structure of Eastern Segment of Central Asian Orogenic Belt and Its Tectonic Implications

The eastern segment of the Central Asian Orogenic Belt (CAOB) in central Inner Mongolia has always been a hot research field in the Earth’s internal dynamics and global change. Tectonic study in this region is of great significance given its important role in understanding the CAOB formation. A 364 km-long magnetotelluric sounding (MT) profile in the eastern CAOB is collected in this study. The profile starts from the northwest near the national border in Dongwuqi of Inner Mongolia, and extends to the southeast through the Northern Orogenic Belt (NOB), Solonker Suture Zone (SSZ) and Southern Orogenic Belt (SOB), and terminates about 30 km west of Wengniuteqi of Inner Mongolia. Based on the data analysis results, 2D inversions were conducted on the dataset. Resulting model shows that the electrical structure of the lithosphere along the profile is characterized by NS-trending transverse blocking. The NOB is generally characterized by low resistivity; The SSZ is the transition zone of the electrical characteristics of the whole section from low to high resistivity; The SOB is mainly characterized by high resistivity. The low resistivity characteristics of NOB indicate that the region is unstable, which may be caused by the residual oceanic crust or asthenospheric upwelling after the Paleo-Asian Ocean closure. The SSZ electrical structure indicates that a new tectonic event may have occurred after the suturing. The high resistivity characteristics of the SOB indicate that the basement is stable and “cold”, and the fluid content is very low, with the geometric characteristics of the electrical structure reflecting the thickened lithosphere. The regional electrical structure characteristics along the profile indicate that new tectonic events, such as asthenospheric fluid ascent and lithospheric thickening, may have occurred after the collision between the Siberian and North China Cratons. In addition, the regional electrical structure is consistent with the suture zone characteristics, which provides new deep geophysical evidence for the continuous accretion model of tectonic evolution in the eastern CAOB.