The contribution and impact of shallow water platform as a potential source area on siliceous submarine fans

The shelf-margin deltas are the primary ‘sources’ of interest in siliceous submarine fan source-to-sink systems. However, less has yet to be discovered about the roles and effects of the shallow water platform situated on continental slopes. Using the Miocene sediments of the Ledong-Lingshui Sag in the western part of the Qiongdongnan Basin (QDNB), this paper studies the YC35 coarse-grained submarine fan that developed in the Meishan Formation (Fm.). The material sources, depositional characteristics, and developmental mechanisms of this fan were investigated. The restored palaeogeomorphology, based on high-resolution 3D seismic data, shows that a shallow water platform exists. According to geochemical palaeoenvironmental data, the shallow water platform was ideal for forming carbonate deposits in the Meishan Fm., owing to the warm and humid palaeoclimate and the shifting trend in palaeowater depth. Based on the combined source tracing of heavy minerals, coherence slices, and seismic profiles, the shallow water platform and the Ningyuan River source on Hainan Island contributed to the YC35 coarse-grained submarine fan. Compared to submarine fans formed during different periods, coarse-grained fan stands out due to its distinct sedimentary structure, rock composition, and microlithological characteristics. Aside from not following the usual Bowmar sequence, there is an excess of gravel and no clear bedding or lamination. A large number of rock fragments, mostly granite and sedimentary rock (carbonatite), make up the rock composition. According to these results, the shallow water platform significantly affects submarine fan material composition. In addition, the attribute slice based on the root mean square reveals that shallow water platforms moderate peripheral deposition. We attribute the development and proximal supply of the shallow water platform to diapirism and forced regression. Our research provides novel insights and comprehension into the investigation of submarine fan sedimentary systems.