HR: 0800h
AN: T41A-1281    [Abstracts]
TI: New geochronological constraints on the movement of Jiali and Gaoligong shear zones in SE Tibet, and its tectonic implication
AU: * Lin, T
EM: f90224101@ntu.edu.tw
AF: Departments of Geosciences, National Taiwan University, No. 245, Choushan Rd., Taipei, 106 Taiwan
AU: Lo, C
EM: loch@ntu.edu.tw
AF: Departments of Geosciences, National Taiwan University, No. 245, Choushan Rd., Taipei, 106 Taiwan
AU: Chung, S
EM: sunlin@ntu.edu.tw
AF: Departments of Geosciences, National Taiwan University, No. 245, Choushan Rd., Taipei, 106 Taiwan
AU: Lee, T
EM: t44001@cc.ntnu.edu.tw
AF: Department of Earth Sciences, National Taiwan Normal University, No. 88, Sec. 4, Tingjou Rd., Taipei, 116 Taiwan
AU: Lee, H
EM: f88224102@ntu.edu.tw
AF: Departments of Geosciences, National Taiwan University, No. 245, Choushan Rd., Taipei, 106 Taiwan
AU: Hsu, F
EM: r87224208@ntu.edu.tw
AF: Departments of Geosciences, National Taiwan University, No. 245, Choushan Rd., Taipei, 106 Taiwan
AB: As a consequence of the northward moving and indentation of India into Asia, crustal fragments around the eastern Himalaya syntaxis were rotated clockwise, and extruded southeastward along the NW-trending Karakoram-Jiali, N-trending Gaoligong and Sagaing faults. Much of the information about the crustal deformation in the India-Asia collision has therefore been registered and recorded in the fault zones. As the easternmost segment of the right-lateral Karakoram-Jiali fault system, the Jiali fault, and its south extension, the Gaoligong fault, provides a great opportunity in revealing the crustal deformation history in Southeast Asia during the collision of India-Asia collision. New laser ⁴⁰Ar/³⁹Ar dating results for migmatites and sheared granitoids in the Bomi and Shama areas along the Jiali fault zone show ages in the range of 11-22 Ma . Whereas hornblende, muscovite, and biotite separates from the Gaoligong fault zone display shorter but concordant ages ranging form 13-18 Ma. ⁴⁰Ar/³⁹Ar ages from the Jiali fault appear to be younger than those reported for the Sagaing fault in Burma (16- 27 Ma, Bertrand et al., 2001). Comparison of these ⁴⁰Ar/³⁹Ar ages suggests that the deformation may start from the south along the Sagaing fault in Indochina, and jump to the areas in the front of the Himalaya, resulting in the shearing of the the Jiali fault, and then propagate toward the south along the Gaoligong fault. Such a deformation history may reflect two stages of extrusion tectonic events during the northward indentation of the India plate into the Asia plate in the Tertiary.
DE: 1115 Radioisotope geochronology
DE: 8111 Continental tectonics: strike-slip and transform
DE: 9320 Asia
DE: 9604 Cenozoic
SC: Tectonophysics [T]
MN: Fall Meeting 2005