Mesozoic evolution of large-scale drainage systems in the Indochina Block: evidence from palaeomagnetic and U–Pb geochronological constraints

Abstract

The collage of the Indochina Block to the Eurasian continent during the Mesozoic resulted in major changes in source-to-sink systems of East Asia, whilst the sedimentation in the Khorat–Simao Basin of the Indochina Block transited from marine to continental environments. Previous studies uncovered the existence of transcontinental river systems in the East Asia mainland during the Cretaceous to Early Cenozoic, although there have been few studies on pre-Cretaceous drainage systems. To determine the impact on the evolution of palaeo-drainage systems triggered by tectonic movement of the Indochina Block, we performed palaeomagnetic and U–Pb geochronologic analyses on the Late Triassic to Early Cretaceous sedimentary rocks in the Simao Basin. Palaeomagnetic data indicate stable Jurassic tectonic environments between the Indochina and Songpan–Ganzi–South China blocks, following their Late Triassic collision. Based on detrital zircon U–Pb dating, the Late Triassic age spectra consist mainly of Phanerozoic components, while the Jurassic to Cretaceous age spectra display more Precambrian age peaks. The contribution of potential provenance to the Simao Basin changed during the Early Cretaceous, suggesting several sedimentary provenance transitions. Also, we believe that large continental-scale drainage systems flowing through the North Qiangtang, Sichuan, Simao and Khorat Basins were sourced from the Songpan–Ganzi Block since the end of the Late Jurassic. Supplementary material: The findings of a quantitative statistical study (Fig. S1; Table S5), the location of the Late Triassic to Early Cretaceous samples from the Simao Basin (Table S1), palaeomagnetic poles for Eurasia, South China, Indochina, North Qiangtang and Tarim (Table S2), the result of quantitative analysis for the Late Triassic and Middle Jurassic sedimentary rocks from the Simao and Sichuan basins (Table S3), and results of zircon U–Pb dating (Table S4) are available at https://doi.org/10.6084/m9.figshare.c.6862918 Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change