HR: 1340h
AN: V13E-0578    [Abstracts]
TI: The Mesozoic Tectono-Magmatic Sequence and Tectonic Dynamic in Southeast China Continent
AU: Mao, J
EM: mjrmh@sina.com;njmjianren@cgs.gov.cn
AF: Mao Jianren, 534 East Zhongshan Road, Nanjing, JS 210016 China
AU: Hu, Q
EM: njhqing@cgs.gov.cn
AF: Mao Jianren, 534 East Zhongshan Road, Nanjing, JS 210016 China
AU: * Guo, K
EM: njgkunyi@cgs.gov.cn
AF: Hu Qing, 534 East Zhongshan Road 8-302, Nanjing, Js 210016 China
AB: There are large-scale magmatism and metallogenic processes in Southeast China, where has been generally considered to posses the characteristics of large igneous province. As a major part of East Asia, Southeast China is very complex region involving multiple stages of the Mesozoic tectono-magmatic activity. Various tectonic models have been proposed in last two decades: (1) an active continental margin related to the subduction of a paleo-Pacific plate (e.g., Jahn et al.,1976; Holloway,1982; Huang et al.,1986; Zhou and Li,2000); (2) an Alpine-type continental collision (Hsu et al., 1988,1990); (3) a wrench fault system (Xu et al.,1987,1993); (4) continental extension and rifting (Gilder et al.,1991,1996; Li,2000) and (5) mantle plume tectonics (Xie et al., 1996; Xie and Mao., 1997; Mao et al.,1999a,1999b; Xie et al., 2001). The Mesozoic tectono-magmatic activity in Southeast China might have been divided into three major stages: Collision and compression of inter-continents between North China and Yangtze block, Indochina and South China block 258-230Ma: Collision and compression of inter-continents between North China plate and Yangtze block-- Ultra-high pressure eclogites in Qingling-Dabi metamorphic zone; Indochina block was converged with the South China block in the north Vietnam and the north Thailand. 250-220Ma: Collision and compression of intra-continents in Cathaysian block-- Peraluminous-weak peraluminous granites of the crust-derived type. 220-180 Ma: Relative `till' of magmatic activity 180-165Ma: Intraplate, extension-,and/or rift-related magmatism. Their mantle sources might have been metasomatizeed by OIB-type melts in an intraplate regime--high-Ti symmetric bi-modal basalt-dacite, alkaline basalts, A-type granite, and potash granodiorites; Transformation from Tethys ( EW-trend, liner distribution ) to Paleo-Pacific active margin (NE-trend, Extensive distribution) regime: beginning of transformation: about 160Ma 165-150Ma: The lithosphere extension and underplating of the basalt magma- widespread peraluminous-metaluminous monzogranite-granites, and potash-syenites displied geochemical and Sr-Nd isotopic affinities of intraplate, extension-,and /or rift-related magmatism. The lithosphere thinning: end of transformation: about 140 Ma Igneous rocks are all demonstrated the cal-alkaline series features and evolutional tendency of an active continental margin or island arc with enrichment in Rb-Th, Zr-Hf and depletion in Ti, Nb-Ta, Ba, Sr, P, Y during this stage. 145-125Ma: Extension-strike slip, the transformation age from Tethys to Paleo-Pacific regime about high-K calc-alkaline dacite-rhyolite volcano-plutonic belt; 125-105Ma: Extension and thinning of the continental lithosphere-Low-Ti asymmetric bimodal basalt-dacite, rhyolite, shoshonite volcano-plutonic rocks; <100Ma: Breakup of the continent- A-type peralkaline granite and basic veins. As mentioned above, authors proposed a tectonic dynamic model: Collision and compression of intra-continents-plate subduction-asthenosphere mantle plume upwelling related to South Pacific super-mantle plume and two crust growth manners, which has been fully considered the mantle plume influence on the Mesozoic uplift and extension as well as the large-scale magmatism in Southeast China.
DE: 1020 Composition of the continental crust
DE: 1645 Solid Earth (1225)
DE: 1744 Tectonophysics
DE: 1749 Volcanology, geochemistry, and petrology
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005