地震反射剖面揭示阿尔泰山陆内逆冲造山机制  

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

作　　者：张蕾 赵连锋 赵亮 谢小碧 田小波 肖文交 姚振兴 Lei Zhang;Lianfeng Zhao;Liang Zhao;Xiaobi Xie;Xiaobo Tian;Wenjiao Xiao;Zhenxing Yao(Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Institute of Geophysics and Planetary Physics,University of California at Santa Cruz,CA 95064,USA;Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China)

机构地区：[1]Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [3]Institute of Geophysics and Planetary Physics,University of California at Santa Cruz,CA 95064,USA [4]Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China

出　　处：《Science Bulletin》2024年第11期1757-1766,共10页科学通报（英文版）

基　　金：supported by the National Key Research and Development Program of China (2017YFC0601206);the National Natural Science Foundation of China (41974061,41974054)。

摘　　要：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 southdipping 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.

关 键 词：Altai mountains Deep seismic reflection profile Subduction-accretion process Intraplate deformation pattern 

分 类 号：P542[天文地球—构造地质学] P315.7[天文地球—地质学]