Late Cenozoic right‐lateral strike‐slip faulting in southern Tibet

Field observations collected during the Sino-French Himalaya-Tibet cooperation project (1980–1982) show that right-lateral faulting between southern and northern Tibet, roughly along the “chord” joining the eastern and western syntaxes of the Himalayan arc, is a major component of the active tectonics north of the Himalayas. Just north of the well developed rifts of southern Tibet, we studied three right-lateral, 100–200 km long, strike-slip faults forming an en echelon array along that chord. Evidence for earthquake surface breaks was found on each of these faults. For the M = 8, Beng Co (or Damxung) strike-slip earthquake of November 18, 1951, rupture parameters could be constrained to be ū = 8 ± 2 m and L = 90 km. Offset glacial and postglacial morphological markers (105 years and 104 years B.P.) imply displacement rates of the order of 1–2 cm/yr on the three faults. The en echelon fault zone appears to extend westward ≈2000 km across the plateau to the Karakorum fault and is thus referred to as the Karakorum-Jiali fault zone (KJFZ). Fast rates of slip on it and on faults along the northern rim of Tibet appear to contrast with the slower rates of deformations in the interior of the plateau. Our estimates of slip rates on the strike-slip and normal faults of southeastern Tibet suggest that eastward extrusion of North Tibet between the right-lateral KJFZ and the left-lateral Altyn Tagh and Kun Lun faults absorbs at least 30% of the present convergence between India and Asia. We propose an instantaneous velocity model of the active tectonics of Asia compatible with such faulting rates and geometries. Evidence for Tertiary right-lateral strike-slip movements in southern Tibet and around the eastern syntaxis of the Himalayas is also found in the structural record. Offsets of various large-scale geological features imply that these movements have been large.

[1]  G. Peltzer,et al.  Formation and evolution of strike‐slip faults, rifts, and basins during the India‐Asia Collision: An experimental approach , 1988 .

[2]  V. Kouskouna,et al.  The 1986 Kalamata (South Peloponnesus) Earthquake: Detailed study of a normal fault, evidences for east-west extension in the Hellenic Arc , 1988 .

[3]  James Jackson,et al.  The relationship between plate motions and seismic moment tensors, and the rates of active deformation in the Mediterranean and Middle East , 1988 .

[4]  D. J. Doornbos,et al.  A comparison of source analysis methods as applied to earthquakes in Tibet , 1987 .

[5]  R. Armijo,et al.  Quaternary extension in southern Tibet: Field observations and tectonic implications , 1986 .

[6]  P. Molnar,et al.  Preliminary conclusions of the Royal Society and Academia Sinica 1985 geotraverse of Tibet , 1986, Nature.

[7]  Philip England,et al.  FINITE STRAIN CALCULATIONS OF CONTINENTAL DEFORMATION .2. COMPARISON WITH THE INDIA-ASIA COLLISION ZONE , 1986 .

[8]  Thérèse Granier.  Origin, damping, and pattern of development of faults in granite , 1985 .

[9]  G. Peltzer,et al.  Neogene and Quaternary faulting in and along the Qinling Shan , 1985, Nature.

[10]  J. Marcoux,et al.  Xainxa ultramafic rocks, central Tibet, China: Tectonic environment and geodynamic significance , 1985 .

[11]  J. Girardeau,et al.  Structure of the Xigaze Ophiolite, Yarlung Zangbo Suture Zone, southern Tibet, China: Genetic implications , 1985 .

[12]  P. Molnar,et al.  FAULTING ASSOCIATED WITH LARGE EARTHQUAKES AND THE AVERAGE , 1984 .

[13]  C. R. Allen,et al.  Red River and associated faults, Yunnan Province, China: Quaternary geology, slip rates, and seismic hazard , 1984 .

[14]  James Ni,et al.  Seismotectonics of the Himalayan Collision Zone: Geometry of the underthrusting Indian Plate beneath the Himalaya , 1984 .

[15]  D. Rothery,et al.  The neotectonics of the Tibetan Plateau , 1984 .

[16]  P. Molnar,et al.  Active faulting and tectonics of Burma and surrounding regions , 1984 .

[17]  J. Marcoux,et al.  Tectonic environment and geodynamic significance of the Neo-Cimmerian Donqiao ophiolite, Bangong-Nujiang suture zone, Tibet , 1984, Nature.

[18]  Wang Xibin,et al.  Structure and evolution of the Himalaya–Tibet orogenic belt , 1984, Nature.

[19]  J. Macdougall,et al.  Isotopic and geochemical evidence for the origin of Plio-Pleistocene volcanic rocks near the Indo-Eurasian collisional margin at Tengchong, China , 1983 .

[20]  P. Molnar,et al.  Focal depths and fault plane solutions of earthquakes under the Tibetan plateau , 1983 .

[21]  P. R. Cobbold,et al.  Propagating extrusion tectonics in Asia: New insights from simple experiments with plasticine , 1982 .

[22]  R. Armijo,et al.  The inverse problem in microtectonics and the separation of tectonic phases , 1982 .

[23]  Z. Garfunkel.  Internal structure of the Dead Sea leaky transform (rift) in relation to plate kinematics , 1981 .

[24]  R. Armijo,et al.  Field evidence for active normal faulting in Tibet , 1981, Nature.

[25]  A. Mitchell.  Phanerozoic plate boundaries in mainland SE Asia, the Himalayas and Tibet , 1981, Journal of the Geological Society.

[26]  P. Molnar,et al.  Active tectonics of Tibet , 1978 .

[27]  J. Ni,et al.  Late Cenozoic tectonics of the Tibetan Plateau , 1978 .

[28]  K. Lassen,et al.  Quiet time pattern of auroral arcs for different directions of the interplanetary magnetic field in the Y‐Z plane , 1978 .

[29]  Thomas H. Jordan,et al.  Present‐day plate motions , 1977 .

[30]  P. Molnar,et al.  Seismic moments of major earthquakes and the average rate of slip in central Asia , 1977 .

[31]  Peter Molnar,et al.  Active faulting and tectonics in China , 1977 .

[32]  P. Molnar,et al.  Cenozoic Tectonics of Asia: Effects of a Continental Collision: Features of recent continental tectonics in Asia can be interpreted as results of the India-Eurasia collision. , 1975, Science.

[33]  W. Broecker,et al.  Quaternary Sea Level Fluctuations on a Tectonic coast: New 230Th/234U Dates from the Huon Peninsula, New Guinea , 1974, Quaternary Research.

[34]  A. Ben-menahem,et al.  The source of the great Assam earthquake — an interplate wedge motion , 1974 .