Rotation of Crustal Blocks as an Explanation of Oligo-Miocene Extension in Southeastern Tibet—Evidenced by the Diancangshan and Nearby Metamorphic Core Complexes

The nature of the Ailao Shan–Red River (ASRR) shear zone: Constraints from structural, microstructural and fabric analyses of metamorphic rocks from the Diancang Shan, Ailao Shan and Day Nui Con Voi massifs

“…For example, low-temperature normal shearing formed a low-grade retrogression zone at the eastern flank of the Cangshan range (Cao et al, 2011). The exhumation of metamorphic core complexes, and generation of grabens and half-grabens indicate a post-left-lateral shearing regional extension event throughout a fan-shaped area between the Red River and Sagaing Faults in Southeast Asia (Liu et al, 2007). Upper crust exhumation of the DCS (Liu et al, 2007), ALS in western Yunan Wang et al, 2000) and DNCV (Tran et al, 1998), Mogok, Doi Inthanon-Doi Suthep and Bukhang complexes (Morley, 2002) in Southeast Asia is, in part, related to the same event (Liu et al, 2007;Cao et al, 2011), a regional late Miocene to Holocene extension (Cao et al, 2011).…”

“…3) and Day Nui Con Voi (Fig. 4) (north to south) have preserved an abundance of information on the thermal and tectonic evolution of the shear zone (Leloup et al, 1995;Tran et al, 1998;Duan and Tan, 2000;Sha and Liu, 2001;Gilley et al, 2003;Liu et al, 2007). The massifs comprise metamorphosed pelitic, mafic and carbonate rocks, which are often interlayered with leucocratic granitic intrusions of various ages Liu et al, 2010;Searle et al, 2010).…”

“…The structural geology, timing of shearing and tectonic implications of the shear zone have been extensively studied over the past few decades Zhong et al, 1990;Schärer et al, 1990Schärer et al, , 1994Harrison et al, 1992Harrison et al, , 1996Leloup et al, 1995;Tran et al, 1998;Wang et al, 1998;Gilley et al, 2003;Searle, 2006;Liu et al, 2007Liu et al, , 2010Anczkiewicz et al, 2007;Sassier et al, 2009;Cao et al, 2010;Searle et al, 2010). Left-lateral shearing was responsible for the large-scale displacement, up to 500 km, and it is primarily assumed to have occurred between 35 and 17 Ma (Leloup and Kienast, 1993;Schärer et al, 1990Schärer et al, , 1994Harrison et al, 1996;Zhang and Schärer, 1999).…”

Exhumation of the Diancang Shan metamorphic complex along the Ailao Shan-Red River belt, southwestern Yunnan, China: Evidence from 40Ar/39Ar thermochronology

“…In the central part of the DCS massif, however, the mylonitic foliation becomes obviously steep. On a Flinn diagram, the high-temperature mylonites plot near the prolate strain field (e.g., Liu et al, 2007). Mesoscopic structures and fabrics include shear bands ( Fig.…”

“…To the eastern and western sides of the DCS massif, are the Cenozoic Erhai Lake basin and the Lanping Mesozoic basin, respectively (e.g., Bureau of Geology and Mineral Resources of Yunan, 1983Yunan, , 1991. Research spanning more than 20 years has provided a wealth of information on the geometry of the ASRR shear zone and its structural, thermal and geomorphologic evolution (e.g., Harrison et al, 1992;Leloup and Kienast, 1993b;Schärer et al, 1990Schärer et al, , 1994Leloup et al, 1995Leloup et al, , 2001aHarrison et al, 1996;Chung et al, 1997;Wang et al, 1998aWang et al, ,b, 2000Zhang and Schärer, 1999;Sun et al, 2003;Burchfiel and Wang, 2003;Gilley et al, 2003;Schoenbohm et al, 2004;Searle, 2006;Liu et al, 2006Liu et al, , 2007Yeh et al, 2008;Cao et al, 2010a,b). Limited thermochronological studies conducted on the massifs, including the DCS of the ASRR shear zone, have focused on the tectono-magmatic evolution with the aim of constraining the timing and amount of displacement, the rate of movement along the shear zone, and the exhumation processes of the metamorphic massifs (e.g., Schärer et al, 1990Schärer et al, , 1994Harrison et al, 1992;Leloup and Kienast, 1993b;Zhang and Schärer, 1999;Gilley et al, 2003;Cao et al, 2010a,b).…”