Source-Sink Response of Sustained Compression Setting in the Xingning Basin on the Southeastern Margin of the South China Block During the Early Cretaceous

Abstract

As three crucial tectonic models, continuous compression, continuous extension and alternating compression and extension have been adopted by scholars to interpret the complex tectonic setting induced by the westward subduction of the Paleo-Pacific Plate beneath the South China Block during the Cretaceous Period. To determine the tectonic model under which the Xingning Basin at the southeastern margin of the South China Block was deposited, this study selects the Upper Cretaceous Heshui Formation in the Xingning Basin as the research target, and carries out sedimentary facies analysis of the study area, and combined with detrital zircon U—Pb geochronology and trace element geochemistry studies. The results indicate that the maximum depositional age of the Heshui Formation is the late Early Cretaceous Albian Stage, and the detrital zircons have two main age groups of 520–380 and 220–100 Ma. The detritus of this age group is mainly from the Wuyi Terrane, and part of it is from the Nanling Terrane, which was briefly uplifted in the late Early Cretaceous. The Paleoproterozoic detritus derived from the Dabie Orogenic Belt in the northern part of the South China Block. This study concludes that the eastern part of the South China Block was affected by subduction in the Early Cretaceous. Specifically, the inland areas experienced episodic compression, followed by a delamination event in the late Early Cretaceous, which triggered a tectonic transition from compression to extension. In contrast, the coastal areas of the South China Block experienced continuous compression, which lasted until the early Late Cretaceous.