HR: 14:40h
AN: T23F-05 INVITED    [Abstracts]
TI: Lithospheric Structure, Crustal Kinematics, and Earthquakes in North China: An Integrated Study
AU: * Liu, M
EM: lium@missouri.edu
AF: University of Missouri, 101 Geology Building, Columbia, MO 65211, United States
AU: Yang, Y
EM: Yanyo@missouri.edu
AF: University of Missouri, 101 Geology Building, Columbia, MO 65211, United States
AU: Sandvol, E
EM: sandvole@missouri.edu
AF: University of Missouri, 101 Geology Building, Columbia, MO 65211, United States
AU: Chen, Y
EM: johnyc@pku.edu.cn
AF: Peking University, Institute of Geophysics, Beijing, 100871, China
AU: Wang, L
EM: lswang@nju.edu.cn
AF: Nanjing University, 22 Hankou Road, Nanjing, 210008, China
AU: Zhou, S
EM: zsy@pku.edu.cn
AF: Peking University, Institute of Geophysics, Beijing, 100871, China
AU: Shen, Z
EM: zshen@xena.ess.ucla.edu
AF: China Earthquake Administration, 63 Fuxin Road, Beijing, 100036, China
AU: Wang, Q
EM: wangql.box@263.net
AF: China Earthquake Administration, 63 Fuxin Road, Beijing, 100036, China
AB: The North China block (NCB) is geologically part of the Archaean Sino-Korean craton. But unusual for a craton, it was thermally rejuvenated since late Mesozoic, and experienced widespread extension and volcanism through much of the Cenozoic. Today, the NCB is characterized by strong internal deformation and seismicity, including the 1976 Tangshan earthquake that killed ~250,000 people. We have started a multidisciplinary study to image the lithospheric and upper mantle structure using seismological methods, to delineate crustal kinematics and deformation via studies of neotectonics and space geodesy, and to investigate the driving forces, the stress states and evolution, and seismicity using geodynamic modeling. Both seismic imaging and GPS results indicate that the Ordos plateau, which is the western part of the NCB and a relic of the Sino-Korean craton, has been encroached around its southern margins by mantle flow and thus is experiencing active cratonic destruction. Some of the mantle flow may be driven by the Indo-Asian collision, although the cause of the broad mantle upwelling responsible for the Mesozoic thinning of the NCB lithosphere remains uncertain. At present, crustal deformation in the NCB is largely driven by gravitational spreading of the expanding Tibetan Plateau. Internal deformation within the NCB is further facilitated by the particular tectonic boundary conditions around the NCB, and the large lateral contrasts of lithospheric strength and rheology. Based on the crustal kinematics and lithospheric structure, we have developed a preliminary geodynamic model for stress states and strain energy in the crust of the NCB. The predicted long-term strain energy distribution is comparable with the spatial pattern of seismic energy release in the past 2000 years. We are exploring the cause of the spatiotemporal occurrence of large earthquakes in the NCB, especially the apparent migration of seismicity from the Weihe-Shanxi grabens around the Ordos to the North China plain in the past 200 years.
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8120 Dynamics of lithosphere and mantle: general (1213)
DE: 8124 Earth's interior: composition and state (1212, 7207, 7208, 8105)
DE: 8164 Stresses: crust and lithosphere
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting