Mesozoic Development of Nonmarine Basins in the Northern Yidun Terrane: Deposition and Deformation in the Eastern Tibetan Plateau Prior to the India‐Asia Collision. Issue 8 (12th August 2018)

• Record Type: Journal Article
• Authors: Jackson, W. T.; Robinson, D. M.; Weislogel, A. L.; Shang, F.; Jian, X.
• Is Part Of: Tectonics. Volume 37:Issue 8(2018)
• Page Start: 2466
• Page End: 2485
• Publication Date: 2018-08-12
• Subjects: Ganzi -- Yidun terrane -- Tibet -- zircon -- nonmarine; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2018TC004995
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: To determine the timing and spatial patterns of syntectonic nonmarine deposition and deformation in the eastern Tibetan Plateau, we present field data, thin section petrology, and detrital U‐Pb zircon geochronology from the west Ganzi basin (WGB) and east Ganzi basin (EGB) in the northern Yidun terrane. The WGB and EGB contain ~800 and ~1, 300–1, 600 m of nonmarine strata, respectively, deposited in alluvial environments. Along the southern margins of both the WGB and EGB and the northwestern margin of the WGB, reverse faults place Triassic Ganzi Pluton and Triassic Yidun Grouprocks on top of nonmarine strata. Growth strata in the footwalls of basin‐bounding faults indicate that deposition was synchronous with fault development. The western and eastern margins of the WGB, as well as the northern margin of the EGB, exhibit uncomformable contacts with the underlying Triassic Ganzi Pluton and Triassic Yidun Grouprocks. Provenance results suggest a regionally mixed sediment source from the Yidun and Songpan‐Ganzi terranes. Maximum deposition ages from detrital U‐Pb zircon geochronology, as well as previously reported thermochronology and palynology results, indicate a Late Mesozoic depositional age for WGB and EGB strata. We interpret the spatial and temporal developments of the WGB and EGB to be associated with the Lhasa‐Qiangtang collision. Key Points: Nonmarine fill of the west Ganzi basin and east Ganzi basin in the northern Yidun terrane consists of Late Mesozoic alluvial strata Provenance analyses suggest that sediment was regionally sourced from rocks in the Yidun and Songpan‐Ganzi terranes The west Ganzi basin and east Ganzi basin developed in a contractional tectonic setting, associated with the Lhasa‐Qiangtang collision