Typical gravity flow sedimentary features and provenance system in Yinggehai-Qiongdongnan Basin, northern South China Sea

Abstract

This study reviewed the sedimentary characteristics and formation mechanism of the Yinggehai-Qiongdongnan Basin based on the lateral sedimentary distribution, vertical sedimentary sequence, and dynamic sedimentary process. Large-scale shallow-water gravity flow deposits developed against a shallow marine background in the Huangliu Formation of the Yinggehai Basin in the northern South China Sea. The submarine fan developed in a semideep marine depositional environment in the Lingshui, Sanya, and Meishan formations of the Qiongdongnan Basin.The main features of shallow marine gravity flow deposits are as follows: ① the scale and distribution patterns of deposits are quite different. ② The sea level changes causes the complexity and variability of sedimentary characteristics. ③ Shallow marine gravity flow deposits usually do not have fan subfacies differentiation of fan subfacies. ④ The channel sandbody of shallow gravity flow is distinguished by rapid migration and thick accumulation, which is reflected by enrichment and multistage stacking of channels.Moreover, the source to sink process and dynamic spatiotemporal changes in different source inputs are revealed through the provenance evolution and comparison of the Yinggehai-Qiongdongnan Basin. The main controlling factors of shallow marine gravity flow development and their coupling relationships are discussed from the aspects of sediment supply, relative sea level change, differential subsidence, and ancient geomorphology (ancient topography break and slope).

Keywords

• yinggehai-qiongdongnan basin
• shallow marine gravity flow
• sedimentary characteristics
• provenance system