近日，中国科学院地质与地球物理研究所赵连峰、赵亮及其课题组近日的研究，报道了深地震反射揭示了阿尔泰山的板内逆冲造山作用。相关论文于2024年3月5日发表在《科学通报》杂志上。

为了阐明阿尔泰山脉是如何在应变速率仅为天山五分之一的情况下产生如此大的隆升，该课题组基于新的166.8km深地震反射剖面，构建了阿尔泰山脉详细的地壳图像。叠前偏移成像显示，额尔齐斯拗陷内部有一个反形态，阿尔泰弧与东准噶尔地区之间有一个约10km的莫霍面偏移，阿尔泰山下地壳中有一个主要的南倾(30°)逆冲断层，该逆冲断层与莫霍面偏移相连。

南倾逆冲断层不仅记录了古生代OB-Zaisan洋的南下俯冲，而且控制了新生代阿尔泰变形模式和鄂尔齐斯反形。额尔齐斯反形阻止了变形向准噶尔峰顶的延伸。阿尔泰地区下地壳的南倾逆冲导致了下地壳挤压，产生地表隆起、地壳增厚和阿尔泰山的莫霍曲线陡直加深(约10 km)的过程。这一过程明显拓宽了阿尔泰山脉的变形带。这些发现为描述继承性地壳结构如果在没有强水平应力的情况下，控制板内变形提供了一种新的地球动力学模型。

据介绍，阿尔泰造山带是中亚典型的大陆内造山带，经历了与印度—欧亚板块汇聚有关的远场变形。该地区与天山具有相当的隆起特征，还具有明显的应变速率。天山山脉容纳印度—亚洲拉力的一半，而阿尔泰山脉只容纳了10%。

附：英文原文

Title: Intraplate thrust orogeny of the Altai Mountains revealed by deep seismic reflection

Author: Lei Zhang, Lian-Feng Zhao, Liang Zhao, Xiao-Bi Xie, Xiaobo Tian, Wenjiao Xiao, Zhen-Xing Yao

Issue&Volume: 2024/03/05

Abstract: The Altai orogen is a typical intracontinental orogen in Central Asia that experienced far-field deformation associated with Indian-Eurasian plate convergence. This region is characterized by uplift comparable to that of the Tianshan Mountains but has a distinct strain rate. Half of the Indo-Asia strain is accommodated by the Tianshan Mountains, whereas the Altai Mountains accommodates only 10%. To elucidate how the Altai Mountains produced such a large amount of uplift with only one-fifth of the strain rate of the Tianshan Mountains, we constructed a detailed crustal image of the Altai Mountains based on a new 166.8-km deep seismic reflection profile. The prestack migration images reveal an antiform within the Erqis crust, an ～10 km Moho offset between the Altai arc and the East Junggar area, and a major south-dipping (30° dip) thrust in the lower crust beneath the Altai Mountains, which is connected to the Moho offset. The south-dipping thrust not only records the southward subduction of the Ob-Zaisan Ocean in the Paleozoic but also controlled the Altai deformation pattern in the Cenozoic with the Erqis antiform. The Erqis antiform prevented the extension of deformation to the Junggar crust. The south-dipping thrust in the lower crust of the Altai area caused extrusion of the lower crust, generating uplift at the surface, thickening of the crust, and steep (～10 km) Moho deepening in the Altai Mountains. This process significantly widened the deformation zone of the Altai Mountains. These findings provide a new geodynamic model for describing how inherited crustal structure controls intraplate deformation without strong horizontal stress.

DOI: 10.1016/j.scib.2024.03.011

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927324001555