The Western Ailaoshan Volcanic Belts and their SE Asia connection: A new tectonic model for the Eastern Indochina Block

The volcaniclastic series from the Luang Prabang Basin, Laos: A witness of a triassic magmatic arc?

“…The exact number of continental fragments and volcanic arcs that actually compose SEA, as well as the timing of their amalgamation, are still controversial and a number of geodynamic models have been proposed to account for the tectonic evolution of the east Tethyan domain (e.g., Ridd, 1971;Burrett, 1974;Sengör, 1979;Mitchell, 1981;Helmcke, 1985;Metcalfe, 1988Metcalfe, , 2002Lepvrier et al, 2004;Ferrari et al, 2008;Carter and Clift, 2008;Cai J.-X. and Zhang K.-J., 2009;Metcalfe, 2011;Liu J. et al, 2012;Cocks and Torsvik, 2013;Lai C.-K. et al, 2014b;Qian X. et al, 2015a). Corollary to these uncertainties about the geodynamic evolution of SEA from the late Paleozoic to the early Mesozoic, the spatial configuration (i.e., the shape) of the blocks that compose the east Tethyan domain and the nature of their boundaries are not precisely known (e.g., Heppe et al, 2007;Wang Q. et al, 2014).…”

Low–temperature eclogite–facies bauxite from the Red River shear zone in Vietnam: Its evolution and significance

“…Several different approaches using metamorphic and igneous rocks from northern to central Vietnam and southern China have revealed the Indochina block collided to the South China block at the Permo-Triassic (e.g., Lepvrier et al, 2004, Osanai et al, 2004, Owada et al, 2006Lepvrier et al, 2008;Nakano et al, 2008Nakano et al, 2010aNakano et al, , 2010bFaure et al, 2014;Lai et al, 2014). The thermal regime of low-T eclogite-facies metamorphism documented in this study is attributed to the collisional event because the presence of eclogite-facies meta-bauxite cannot be explained by any other thermal regimes (e.g., subduction zone metamorphism).…”

Zircon U–Pb ages, Hf isotope data, and tectonic implications of Early–Middle Triassic granitoids in the Ailaoshan high-grade metamorphic belt of Southeast Tibet

“…Several studies have proposed that the initial opening of the Jinshajiang-Ailaoshan-Song Ma Ocean began in the Silurian (Jian et al 2009b;Xia et al 2015) and that oceanic spreading continued from the Late Devonian to the early Permian (Wang et al 2000;Jian et al 2008Jian et al , 2009aZi et al 2012a;Vuong et al 2013;Lai et al 2014b). Based on the existence of a volcano-plutonic arc along the eastern margin of the eastern QiangtangSimao-Indochina block, it is commonly interpreted that the oceanic lithosphere underwent westward subduction from the middle Permian to the Early Triassic (Jian et al 2009a, b;Fan et al 2010;Liu et al 2011;Zi et al 2012b;Lai et al 2014a). Subsequently, the collision of the eastern Fig.…”

“…1 a Distribution of principal continental blocks of Southeast Asia (modified after Deng et al 2014); b simplified geological map of Sanjiang region (modified after Liu et al 2012b;Zi et al 2013;Deng et al 2014). ALSF Ailaoshan fault, DBFF Dien Bien Phu fault, LMSF Longmenshan fault, NTHF Nantinghe fault, RRF Red River fault, XSHF Xianshuihe fault, XJF Xiaojiang fault Qiangtang-Simao-Indochina and Yangtze blocks resulted in collision-related magmatism, metamorphism, and deformation (Zhu et al 2011;Liu et al 2012bLiu et al , 2014Liu et al , 2015aZi et al 2012cZi et al , 2013Lai et al 2014a). All the geological units are unconformably overlain by the Late Triassic molasse sequences, marking the final closure of the main Paleo-Tethyan Ocean (Zhong 1998;Wang et al 2000).…”

“…In addition to controversy regarding the subduction polarity Mo et al (1998), Jian et al (2009b, Qi et al (2010), Liu et al (2011, 2015a, Li et al (2008), Lin et al (2012), Lai et al (2014a, b), and this study; b schematic geological map of Laowangzhai-Shuanggou area, showing the major tectonic units of the Jinshajiang-Ailaoshan-Song Ma Ocean, the spatial-temporal evolutions of the Jinshajiang Ocean compared with the Ganzi-Litang Ocean, and of the Song Ma Ocean compared with the Song Da rift, are widely debated (Lepvrier et al 2004;Reid et al 2005;Roger et al 2008Roger et al , 2010Liu et al 2012b). The extensive volcanic and plutonic rocks to the west of the Ailaoshan suture zone are considered to be the products of the westward subduction of the Ailaoshan oceanic plate beneath the Simao block (Jian et al 2008(Jian et al , 2009aFan et al 2010;Liu et al 2011Liu et al , 2015aLai et al 2014a). Some granitoids, although cropping out to the east of the Ailaoshan suture zone or even within the Ailaoshan high-grade metamorphic belt, have also been attributed to subduction/collision Qi et al 2010;Lin et al 2012;Lai et al 2014b;Liu et al 2014Liu et al , 2015a.…”