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

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 conducted the existence of transcontinental river systems in the East Asia mainland during the Cretaceous to early Cenozoic with few studies on pre-Cretaceous drainage systems. To determine the impact on the evolution of paleo-drainage systems triggered by tectonic movement of the Indochina Block, we performed paleomagnetic and U-Pb geochronologic analyses on the Late Triassic to Early Cretaceous sedimentary rocks in the Simao Basin. Paleomagnetic 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 of mainly Phanerozoic components, while the Jurassic to Cretaceous age spectra displayed 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 sourced from the Songpan-Ganzi Block flowing through North Qiangtang, Sichuan, Simao, and Khorat basins since after the Late Jurassic. 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 Supplementary material: https://doi.org/10.6084/m9.figshare.c.6862918