Sedimentary Records of the Late Cretaceous-Paleogene Tectonic Transition in the Eastern South China Block: A Case Study of the Nanxiong Basin, Northern Guangdong Province

Formation and evolution of the Nanxiong Basin were dominated by the transformation of the Late Cretaceous-Paleogene tectonic mechanism in the eastern South China Block. In this paper we report new detrital records and sedimentary characteristics of the sediments and U-Pb geochronology of detrital zircons from siliciclastic rocks in the basin. These results indicate that the Nanxiong Basin is an asymmetrical extensional rift basin and constitutes the half-graben tectonic system with granites on both sides. The basin formed in the late Early Cretaceous under a background of regional tectonic extension, and accumulated the Late Cretaceous to Paleocene red siliciclastic rocks that unconformably overlies the Precambrian and lower Paleozoic sequences. U-Pb ages of detrital zircons from the siliciclastic rocks suggest that the sediments at the base of basin mainly came from the Precambrian-Lower Paleozoic strata, whereas the detritus at the upper part of the basin mainly came from the Caledonian, Indosinian, and Early Yanshanian granites exposed on both sides of the basin, which reveals a history of uplift and denudation of the granites accompanying with the evolution of the basin. Considering the sedimentary facies and provenance changes, it is believed that the formation and evolution of the Nanxiong Basin experienced a transition from expansion to atrophy, which is in accordance with the extension to compression tectonic transformation in the eastern South China Block during Late Cretaceous to Paleocene. The transformation is attributed to both of the collision between the Indian and the Eurasian plates and the subduction of the Pacific plate in Mid-Late Paleocene (ca. 60 Ma). © 2019, Science Press. All right reserved.