Subsidence and exhumation of the Mesozoic Qiangtang Basin: Implications for the growth of the Tibetan plateau
J. Zhang, H. D. Sinclair, Y. Li, C. Wang, C. Persano, X. Qian, Z. Han, X. Yao and Y. Duan
Journal name: Basin Research
Issue: Vol 31, No 4, August 2019 pp. 754 - 781
Info: Article, PDF ( 2.91Mb )
The subsidence and exhumation histories of the Qiangtang Basin and their contribu-tions to the early evolution of the Tibetan plateau are vigorously debated. This paper reconstructs the subsidence history of the Mesozoic Qiangtang Basin with 11 selected composite stratigraphic sections and constrains the first stage of cooling using apatite fission track data. Facies analysis, biostratigraphy, palaeo‐environment interpretation and palaeo‐water depth estimation are integrated to create 11 composite sections through the basin. Backstripped subsidence calculations combined with previous work on sediment provenance and timing of deformation show that the evolution of the Mesozoic Qiangtang Basin can be divided into two stages. From Late Triassic to Early Jurassic times, the North Qiangtang was a retro‐foreland basin. In contrast, the South Qiangtang was a collisional pro‐foreland basin. During Middle Jurassic-Early Cretaceous times, the North Qiangtang is interpreted as a hinterland basin between the Jinsha orogen and the Central Uplift; the South Qiangtang was controlled by subduc-tion of Meso‐Tethyan Ocean lithosphere and associated dynamic topography com-bined with loading from the Central Uplift. Detrital apatite fission track ages from Mesozoic sandstones concentrate in late Early to Late Cretaceous (120.9–84.1 Ma) and Paleocene–Eocene (65.4–40.1 Ma). Thermal history modelling results record Early Cretaceous rapid cooling; the termination of subsidence and onset of exhuma-tion of the Mesozoic Qiangtang Basin suggest that the accumulation of crustal thick-ening in central Tibet probably initiated during Late Jurassic–Early Cretaceous times (150–130 Ma), involving underthrusting of both the Lhasa and Songpan–Ganze ter-ranes beneath the Qiangtang terrane or the collision of Amdo terrane.