Provenance analysis of the Mesozoic Hoh‐Xil‐Songpan‐Ganzi turbidites in northern Tibet: Implications for the tectonic evolution of the eastern Paleo‐Tethys Ocean

Abstract

Mesozoic strata of the Hoh‐Xil‐Songpan‐Ganzi complex in northern Tibet are exposed in a vast (> 370,000 km2) triangle‐shaped orogenic belt bound by the Longmen Shan thrust belt in the east, the Kunlun terrane and North China block in the north, and the Qiangtang terrane and Yidun arc in the south. These strata consist of Middle–Upper Triassic submarine fan and deep marine facies rocks that were deposited in the Paleo‐Tethys Ocean. Late Triassic–Early Jurassic contractional deformation in the eastern Hoh‐Xil‐Songpan‐Ganzi complex marks the demise of the Paleo‐Tethys Ocean basin and the accretion of the Gondwana‐derived Qiangtang terrane to Eurasia. We conducted geological mapping, regional stratigraphic analyses, and U‐Pb geochronology of detrital zircons (n = 4128) on the Mesozoic sequences exposed in the Hoh‐Xil‐Songpan‐Ganzi complex, Kunlun terrane, and Qiangtang terrane. We identify for the first time marine silciclastic sandstone and shale of Jurassic age in the northwestern Hoh‐Xil‐Songpan‐Ganzi complex that unconformably overlie Upper Triassic turbidites. Zircon age data indicate that the Middle–Upper Triassic marine gravity‐flow deposits of the Hoh‐Xil‐Songpan‐Ganzi complex were shed from the North and South China blocks, and Middle–Late Triassic ultrahigh‐pressure Qinling–Dabie orogenic belt, as well as the Kunlun and Qiangtang terranes. In addition, the detrital zircon results suggest vast sediment source to sink distances (>1500 km) for the Middle–Upper Triassic Hoh‐Xil‐Songpan‐Ganzi strata, which is consistent with tectonic models for the Paleo‐Tethys Ocean basin that incorporate significant components of horizontal tectonic transport like opening of large back‐arc basins in response to oceanic slab rollback.

Petrogenesis and tectonic implications of Triassic mafic complexes with MORB/OIB affinities from the western Garzê-Litang ophiolitic mélange, central Tibetan Plateau

“…These geochemical and mineralogical features strongly suggest a continental back-arc spreading environment. Provenance studies of the Mesozoic turbidites in the BSG terrane near the GLS indicate that MiddleUpper Triassic marine gravity-flow deposits were shed from the North China and South China blocks, the ultrahigh-pressure Qingling-Dabie orogenic belt and the Kunlun and Qiangtang terranes (She et al, 2006;Weislogel et al, 2006;Zhang et al, 2008a) over vast sediment sourceto-sink distances (N1500 km) for the Middle-Upper Triassic BSG strata, and this result is also consistent with the tectonic model that depicts the opening of large back-arc basins in response to oceanic slab rollback (Ding et al, 2013).…”

Provenance and tectonic evolution of Lower Paleozoic–Upper Mesozoic strata from Sibumasu terrane, Myanmar

“…In contrast, detrital zircon ages of the Triassic strata in the southern Qiangtang terrane are dominated by age populations of 300-200 Ma and 2.0-1.8 Ga and few ages between 1000-500 Ma (Pullen et al, 2008;Gehrels et al, 2011;Ding et al, 2013).…”

Late Permian–Triassic siliciclastic provenance, palaeogeography, and crustal growth of the Songpan terrane, eastern Tibetan Plateau: evidence from U–Pb ages, trace elements, and Hf isotopes of detrital zircons

“…Nie et al 1994;Gu 1994;Zhou and Graham 1996;Bruguier et al 1997;Weislogel et al 2006Weislogel et al , 2010She et al 2006;Liu et al 2006;Su et al 2006;Zhang et al 2006aZhang et al , 2006bZhang et al , 2007bZhang et al , 2008Zhang et al , 2012Zhang et al , 2014aZhang et al , 2014bWang et al 2007;Enkelmann et al 2007;Weislogel 2008;Deng et al 2008;Ding et al 2013). However, because of the strong deformed strata (e.g.…”