HR: 1330h
AN: T42B-0286    [PDF]
TI: Tectonic Evolution of South China Coastal Provinces Since the Mid-Mesozoic
AU: * Chan, L
EM: chanls@hkucc.hku.hk
AF: Hong Kong University, Pokfulam, Hong Kong, 00000 Hong Kong
AU: Pubellier, M F
EM: pubellier@geologie.ens.fr
AF: Ecole Normale Superieure, 23 Rue Lhomond, Paris, 75 F-75231 France
AU: Phung, P V
EM: pvphach@vista.gov.vn
AF: Hanoi Inst. Oceanography, Nghia Do - Cau Giay, Hanoi, 208D Viet Nam
AU: Mechti, M
EM: mechti@geologie.ens.fr
AF: Ecole Normale Superieure, 23 Rue Lhomond, Paris, 75 F-75231 France
AU: Leung, K F
EM: leungkarfai@graduate.hku.hk
AF: Hong Kong University, Pokfulam, Hong Kong, 00000 Hong Kong
AU: Ego, F
EM: ego@geologie.ens.fr
AF: Ecole Normale Superieure, 23 Rue Lhomond, Paris, 75 F-75231 France
AB: Structural analysis using satellite imageries and detailed field studies with fault-slip data inversions in critical areas in Guangxi and Guangdong Provinces and Hong Kong reveal a polyphase tectonic history in the southeastern margin of South China, which essentially resulted from the passive reaction of the region to relative motions of neigboring plates during various times. Northward subduction of the Paleo Kula-Pacific plate under South China during Middle Jurassic-Early Cretaceous (Yenshanian arc) created a volcanic arc-back-arc setting with left-lateral shear partitioning along ductile fault zones and occasional left-lateral pull apart basins. Subduction was blocked in the late Upper Cretaceous resulting in shortening of the back-arc region and, reactivation of older faults (e.g . Nanxiong B. in Guangdong \& Mirs B. in Hong Kong), followed by orogen collapse with local detachment faulting and narrow molasse basins. The extensional setting continued during Eocene-Oligogene with rifting characterized by the formation of offshore basins and expansion of the continental shelves. The extension was accompanied by left-lateral transtensional basins along NW-trending faults transfer faults (Baise B. in Guangxi), probably influenced by the left-lateral motion of the Red River Fault. The area entered a period of relative tectonic quiescence during early Oligocene-mid Miocene when South China Sea formed, with little stratigraphic record preserved on land. Tectonic exhumation in the Red River region at around 20 m.y. produced NW-trending extensional structures in the region. Southerly extrusion of the Kunming Block in the western part and subduction process in the east during the mid-Miocene-Pliocene resulted in E-W extension in the region, and local N-S compression in southern Tonkin. The westward subduction of the Philippine Plate and the reversal to right-lateral motion on the Red River Fault since 5 m.y.b.p. resulted in right-lateral motion and formation of pull-apart basins along NE-trending faults in the region (e.g. Haifeng B. in Guangdong). [Support from HKU and PROCORE programme is gratefully acknowledged].
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 8105 Continental margins and sedimentary basins
DE: 8107 Continental neotectonics
DE: 8109 Continental tectonics--extensional (0905)
SC: Tectonophysics [T]
MN: 2003 Fall Meeting