Pre-Oxfordian (>163 Ma) Ophiolite Obduction in Central Tibet

The timing of Bangong-Nujiang suture ophiolite obduction between the Lhasa and Qiangtang terranes in central Tibet is important for understanding the closure history of the Meso-Tethys but remains poorly constrained. We investigated subaerial to shallow marine strata of the Dongqiao Formation that sit unconformably on Bangong-Nujiang suture ophiolites that crystallized in a supra-subduction zone setting at 189–181 Ma. Based on foraminiferal and coral studies, the depositional age of the Dongqiao Formation is constrained to be Oxfordian and Kimmeridgian (Late Jurassic). Provenance analyses including detrital modes, geochemistry of detrital chromian spinels, and U-Pb age populations of detrital zircons suggest the Dongqiao Formation was sourced from uplifted Bangong-Nujiang suture ophiolites and sedimentary and metamorphic rocks of Lhasa terrane affinity to the south. We conclude that Bangong-Nujiang suture ophiolites were obducted soon after crystallization (prior to Oxfordian time; >163 Ma) onto the Lhasa terrane or a microcontinent of Lhasa terrane affinity.