Miocene-Recent Crustal Reactivation of the North Tibetan Foreland, Western Hexi Corridor and Southern Beishan, China: Implications for Intraplate Earthquake Hazards in Slowly Deforming Regions of Central Asia

Session: Seismicity and Tectonics of Stable Continental Interiors
Type: Oral
Date: 4/30/2020
Time: 09:15 AM
Room: 240
Description: 

The Gobi Corridor region north of Tibet is one of the world’s finest natural laboratories for documenting lithospheric controls on the distribution and kinematics of intraplate faulting and associated mountain building. Earthquake, geodetic, geomorphic and structural data in the north Tibetan foreland, Beishan, Hexi Corridor and Gobi Altai indicate that a diffuse network of Quaternary faults has accommodated sinistral transpressional deformation as a distant response to NE-directed compressional stresses driven by the continued Indo-Eurasia collision, 2000+ km to the south. Gobi Corridor crust is a Paleozoic terrane collage (Central Asian Orogenic Belt) sandwiched between rigid Precambrian-Archaean cratons that was repeatedly reactivated during the Permo-Triassic, Jurassic, Cretaceous and Neogene. Late Cenozoic reactivation was likely facilitated by thermal weakening of the crust due to Jurassic-Miocene volcanism and diffuse Cretaceous rifting and crustal thinning. Active faults north of Tibet terminally accommodate intraplate strain in oblique deformation belts dominated by restraining bends, horsetail splay thrust ridges and individual thrust ranges that collectively define a transpressional basin and range physiographic province. Although terrane boundaries and other faults are reactivated in many areas, thrust and oblique-slip reactivation of WNW striking shallowly dipping sedimentary bedding and metamorphic fabrics is locally important. Conversely, modern E-W trending strike-slip faults typically crosscut older basement trends. In the Gobi Altai, southern Beishan and along the northern margin of Tibet, the Late Cenozoic fault array is best described as an evolving transpressional duplex. Throughout the Gobi Corridor, tectonic loading is shared amongst a diffuse fault network challenging assumptions about earthquake recurrence intervals and seismic hazard forecasting.

Presenting Author: Dickson Cunningham

Authors