Intracontinental Orogenic Crustal Deformation in Transition Zone Between the NE Tibet and the Ordos Basin Revealed by a Dense Short-Period Seismic Array

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

The crustal deformation in intracontinental orogen as a far-field response of the collision between the Indian and Eurasian plates is a key problem to understanding the Asian tectonic evolution in Cenozoic. The Liupan Shan mountain, located in the transition zone between the northeastern corner of the Tibetan Plateau and the southwestern of Ordos basin, has been uplifted since Later Miocene. We carried a 170-km-long dense short-period seismic array across the northern Tibetan plateau, the Ordos basin and their boundary (Liupan Shan fault) with station spacing 500 meters. Receiver functions are calculated from the waveform of teleseismic events and used to image the crustal structure. Our results show the Moho increases eastward from 50 km beneath the Longxi Basin to 57 km beneath the Liupan Shan, and then decreases to 48 km beneath the southwest of Ordos basin. The crustal image shows that the upper-crust of the plateau is overthrust on the Ordos, and while the lower-crust of the plateau underthrust beneath the Ordos crust, while the Ordos crust is inserted as a wedge into the plateau crust beneath the Liupan Shan. We propose that this kind deformation style, which is different with that in the Qilian Shan and Longmen Shan, is attributed to a strong crust beneath Longxi Basin unlike other parts of plateau margin with a weak crust.

Presenting Author: Xiaobo Tian

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