Generation and emplacement of Triassic granitoids within the Songpan Ganze accretionary-orogenic wedge in a context of slab retreat accommodated by tear faulting, Eastern Tibetan plateau, China

Denudation pattern across the Longriba fault system and implications for the geomorphological evolution of the eastern Tibetan margin

“…1). Thrusting results from positive tectonic inversion of Paleozoic to early Mesozoic passive margin normal faults, affecting the western edge of the Yangtze craton (Mattauer et al, 1992;Roger et al, 2010;de Sigoyer et al, 2014). The Beichuan fault, which is the main active structure of the Longmen Shan, contributed to the exhumation of the Yangtze crystalline basement during early Cenozoic times (Arne et al, 1997;Kirby et al, 2002;Li et al, 2012;Wang et al, 2012;Cook et al, 2013;Tian et al, 2013).…”

New geochronology constraints on timing and depth of the ancient earthquakes along the Longmen Shan fault belt, eastern Tibet

“…A tectonic model involving crustal material migration along this detachment was hence proposed for the LSFB, which caused the formation of ductile shear zones, metamorphic domes, and magmatism [ Zhou et al ., ; Roger et al ., ; Yan et al ., ]. Most of the postorogenic granitoids were A‐type granites with Jurassic ages (200–150 Ma), different from adakitic type of the Indosinian ages (225–200 Ma), demonstrating the transition from compressional to extensional deformation [ Roger et al ., , ; de Sigoyer et al ., ]. The postcollisional orogeny was thus a consequence of the collapse of the thickened Songpan‐Ganze fold belt.…”

“…The flysch sediments deposited in this basin are disconformably underlain by a thick (5–7 km) Paleozoic cover of marginal deposits that consist of a thick (5–10 km) metasedimentary accretionary‐orogenic wedge involving Lower and Middle Triassic turbidites. Accompanied with the closure of the Palaeotethys ocean, the flysch successions started to fold and thicken, which induced extensive magmatism between 228 and 195 Ma age, encompassing a large variety of petrologic and geochemical signatures (Figure b) [ Roger et al ., , ; Zhang et al ., , ; Xiao et al ., ; Yuan et al ., ; de Sigoyer et al ., ; Jolivet et al ., ]. The Palaeozoic platform layers are only exposed along the eastern margin of the Songpan‐Ganze unit as a consequence of the strong erosion and are generally underthrusting the Triassic flysch cover (Figure c). Along a SW‐NE narrow belt, four crystalline complexes (Tonghua, Baoxing, Xuelongbao, and Pengguan complexes; see locations in Figure b) occupy a large portion of the LSFB.…”

Constructing the Eastern Margin of the Tibetan Plateau During the Late Triassic

“…The results are plotted on a concordia diagram (Figure S1) and a 206 Pb/ 238 U distribution diagram (Figure S2). Concentration of selected major and trace elements (SiO 2 , MgO, Rb, Sr, Y, La, and Yb) of the analyzed samples and compiled data from previous studies (Bai et al, , ; Cai, ; Cai et al, , ; Q. Chen et al, ; Cui et al, ; Dai et al, ; Deschamps et al, ; de Sigoyer et al, ; Lai & Zhao, ; Shi et al, ; Wan et al, ; Wen, ; Xia et al, ; Xiao et al, ; S. W. Yan et al, ; J. Yuan et al, ; C. Yuan et al, ; H. F. Zhang et al, , ; Zhao et al, ) is reported in Table S2. Thus, a data set consisting of 335 samples was created and these data were grouped into 40 data subsets based on similar age and geographical location (Table S2).…”