Cretaceous exhumation of the Triassic intracontinental Xuefengshan Belt: Delayed unroofing of an orogenic plateau across the South China Block?

Chu, Yang; Lin, Wei; Faure, Michel; Allen, Mark B.; Feng, Zhentian

Abstract

A large plateau can be produced by crustal thickening in convergent zones such as continental collision belts and Andean-type subduction zones, but the life cycles of such plateaux are not well-understood. In particular, it is not clear how long they persist after construction, before other tectonic processes or erosion reduce crustal thickness and elevation to near-normal levels. Triassic subduction- and collision-tectonics produced intense deformation, magmatism and metamorphism across the entire South China Block. This large-scale crustal shortening created a broad orogenic belt, uplifted most parts of the South China Block, and probably initiated the growth of an orogenic plateau. Our study presents low-temperature thermochronology data from the Xuefengshan Belt in the interior of the South China Block. There was along-strike variation in exhumation. The north orogenic core was subjected to Triassic (~245–210 Ma), and Late Cretaceous (~100–80 Ma) exhumation, whereas the cooling path of the south orogenic core reflects a two stage Cretaceous evolution. The variable exhumation pattern reflects non-uniform tectonics in different regions, but both regions were subject to Late Cretaceous extension. We tentatively reconstruct the original plateau paleo-elevation to be ~1.5 km above sea level, based on the amount of exhumation (~10 km) and the present crustal thickness (~35 km). The T-t trajectories of the Xuefengshan Belt and other Triassic belts highlight the significance of Cretaceous extension and exhumation in shaping the tectonic configuration of the South China Block. Large-scale extension was probably triggered by rollback of the Paleo-Pacific subduction zone.

Citation

Chu, Y., Lin, W., Faure, M., Allen, M. B., & Feng, Z. (2020). Cretaceous exhumation of the Triassic intracontinental Xuefengshan Belt: Delayed unroofing of an orogenic plateau across the South China Block?. Tectonophysics, 793, Article 228592. https://doi.org/10.1016/j.tecto.2020.228592

• Journal Article Type: Article
• Acceptance Date: Aug 11, 2020
• Online Publication Date: Aug 26, 2020
• Publication Date: 2020-10
• Deposit Date: Sep 18, 2020
• Publicly Available Date: Aug 26, 2021
• Journal: Tectonophysics
• Print ISSN: 0040-1951
• Electronic ISSN: 1879-3266
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 793
• Article Number: 228592
• DOI: https://doi.org/10.1016/j.tecto.2020.228592
• Public URL: https://durham-repository.worktribe.com/output/1262048