Late Triassic thickening of the Songpan–Ganzi Triassic flysch at the edge of the northeastern Tibetan Plateau

摘要: Growing geologic evidence documents incremental Mesozoic and early Cenozoic shortening thickening of the Tibetan crust prior to onset main orogenic event. The shows spatial temporal variability in thickness, style, timing thickening, plateau-forming processes. Songpan–Ganzi area northeastern Tibet provides for Late Triassic time. An oil exploratory well (HC-1) 7012.4 m located at least six tectonic repetitions, resulting more than ∼46% sequence. It indicates that true thickness flysch is not 10–15 km as previously assumed, but 3–5 km. Based on this evidence, combined with tectonostratigraphic studies, we propose substantial crustal leading initial plateau formation Plateau, had already occurred during Triassic.