Tectonic implications of felsic tuffs within the Lower Miocene Gangrinboche conglomerates, southern Tibet

Southern Tibetan Oligocene–Miocene adakites: A record of Indian slab tearing

“…In southern Tibet, the Oligo-Miocene Gangringboche basin developed along nearly the entire length of the Yarlung-Zangbo suture ( Fig. 1a; Aitchison et al, 2002Aitchison et al, , 2009DeCelles et al, 2011). Stratigraphic studies of the Gangrinboche conglomerates are consistent with deposition in an extensional setting (DeCelles et al, 2011).…”

“…Extrusive volcanic rocks in the range of 26-20 Ma have also been documented within the Kailas/Gangrinboche Formation ( Fig. 1a; Aitchison et al, 2009;DeCelles et al, 2011), which is distributed 1500 km along strike of the Yarlung-Zangbo suture (Aitchison et al, 2002). N-S trending dike swarms of 12-9 Ma are exposed several kilometers south of the Yarlung-Zangbo suture zone (Fig.…”

“…1a; Chung et al, 2005;Ding et al, 2003;Gao et al, 2007a;Guo et al, 2006;Mahéo et al, 2002Mahéo et al, , 2009Turner et al, 1996;Williams et al, 2004) and plutons/dikes with adakitic compositions in southern Tibet (Lhasa terrane) over 1500 km along the strike of the orogen within a narrow belt approximately paralleling the YarlungZangbo suture (Aitchison et al, 2009;Chung et al, 2003Chung et al, , 2009Gao et al, 2007b;Guo et al, 2007b;Hou et al, 2004Hou et al, , 2013Ji et al, 2009a, b;Li et al, 2011;Pan et al, 2012;Ravikant et al, 2009;Xu et al, 2010a;Zheng et al, 2012a,b). The majority of these rocks are intermediate to silicic in composition.…”

“…In a broader sense, three main geodynamic models have been proposed to explain the occurrence of post-collisional magmatism in Tibet: (1) convective removal of a lithospheric root beneath the plateau (Chung et al, 2005;Miller et al, 1999;Nomade et al, 2004;Turner et al, 1996); (2) intracontinental subduction (Arnaud et al, 1992;Ding et al, 2003Ding et al, , 2007Wang et al, 2005Wang et al, , 2008 and (3) roll-back and break-off of the subducted Indian continental lithospheric slab (Aitchison et al, 2009;DeCelles et al, 2011;Guo et al, 2013;Mahéo et al, 2002Mahéo et al, , 2009Miller et al, 1999;Pan et al, 2012). These hypotheses are intensely debated and there is little consensus in the literature as to which one best explains regional observations in southern Tibet.…”

“…Slab tearing may also geodynamically explain the timing, distribution and thickness of the Gangrinboche/Kailas basin filling (Aitchison et al, 2002(Aitchison et al, , 2009DeCelles et al, 2011) along the Yarlung-Zangbo suture zone and, in part, interpret the slip history along the right-lateral Jiali fault .…”