Tuesday, December 13, 2016

Highlights: Tibetan Forearc Basin Evolution

Forearc basins are depositionally important tectonic elements of ocean-continent collision zones, and commonly contain strata influenced by subduction and magmatic arc evolution. However, detailed spatial and temporal understanding of the timing and mechanisms of forearc development is limited, in part because these basins are rarely exhumed and easily accessible on land. To better understand tectonics and sedimentation of forarc basins, Orme and Laskowski examine Albian–Santonian strata of southern Tibetan Xigaze forearc basin, a large and well-preserved forearc basins, and which records upper-plate processes active prior to and following the inter-continental collision between India and Asia. Using regional geologic mapping, detailed sedimentologic and facies analysis, modal petrographic characteristics, and U-Pb detrital-zircon geochronologic data, the study documents the relationship between the Yarlung-Tsangpo ophiolite and Xigaze forearc basin and reconstructs the sedimentary environments of the southern margin of Asia during the initial stages of forearc deposition. Results reveal details of the evolution of the southern margin of Asia prior to its collision with India, including diachronous development of the forearc basin prior to India–Asia collision.

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