第七届青年地学论坛

Mesozoic-Cenozoic landscape evolution of the East Asia reflects the dynamic coeval tectonic interactions between the Asian and surrounding plates, including the westward subduction of the Pacific plate in the east, the consumption of the Neo-Tethys and subsequent Cenozoic Indo-Asia collision in the west, and Oligocene-Early Miocene opening of the South China Sea in the southeast. A widely accepted landscape evolution model for the East Asia suggested that Cretaceous-Paleogene landscape was west-tilting, characterized by extensive high coastal mountains in the east and relatively low terrains in the west. Here we testify this model by reconstructing the paleodrainage evolution that is sensitive to large-scale topographic adjustment. Our paleodrainage reconstructions, using paleocurrent and zircon U-Pb analyses, focus on four contiguous sedimentary basins (namely Yulin, Shiwandashan, Nanning, and Baise), extending for ~500 km in the South China Block. Results show that the paleodrainages feeding the basins evolved from Cretaceous west-flowing, via Paleogene bidirectional, to Late Oligocene (<33 Ma) modern-like east-flowing, suggesting the landscape evolved from Cretaceous west-tilting, via a Paleogene transitional V-shaped landscape, to Late Oligocene-present east-tilting. These reconstructions  are consistent with recent paleo-elevation studies, suggesting Eocene surface uplift of the southeast Tibetan Plateau, which heralded the dominance of the Indo-Asia collision in sculpting the landscape of the East Asia.
 

East Asia,landscape evolution,sediment provenances