Topography and tectonic setting of the study region. The surface topography is from the ETOPO2 data set (National Geophysical Data Center 2006). Plate boundaries (indented lines) are from www-udc.ig.utexas.edu. Boundaries between major crustal blocks (thick grey dashed lines or thick black lines), and important regional faults (thin black lines) are simplified from previous regional studies (Ren et al. 1999; Ren & Liu 2002; Sone & Metcalfe 2008; Pan et al. 2012). Thick white arrow denotes the current movement direction of the Indian Plate at 90°E, 26°N relative to Eurasia (Kreemer et al. 2014). Inset map shows the study region in Asia. Abbreviations are as follows: AS = Ailaoshan Suture, ATF = Altyn Tagh Fault, BM = Burma Microplate, BNS = Bangong–Nujiang suture, CAOB = Central Asian Orogenic Belt, IT = Indochina Terrane, JRS = Jinsha River Suture, KF = Kunlun Fault, LMSF = Longmenshan Fault, LS = Lanchangjiang Suture, MFT = Main Frontal Thrust, NCC = North China Craton, NQT = North Qaidam Thrust, NT = Naga Thrust, QSFT = Qilian Shan Frontal Thrust, RRF = Red River Fault, SCC = South China Craton, SF = Sagaing Fault, SGT = Songpan–Ganzi Terrane, YZS = Yarlung Zangbo Suture.