Proliferation of submarine channels during the Late Miocene in the northwest South China Sea linked to multiple provenance and climate cooling

Sandy-infilled submarine channels are critical hydrocarbon reservoirs in offshore basins. The Yinggehai Basin (Southeast Asia’s major Cenozoic offshore basin) has well-developed submarine channels， but their evolutionary mechanisms remain unclear. This study deciphers controls on Upper Miocene Huangliu Formation channel-complex evolution in this basin. An integrated approach with 3D seismic data interpretation， well log analysis， sedimentary facies identification， and detrital zircon U-Pb geochronology， showing a clear morphological transition: early deeply incised meandering channels evolved into late extensive braided complexes. Detrital zircon dating links initial incision (early Late Miocene) to high-energy gravity flows from northern Hainan Island， coinciding with global cooling and marine regression. A mid-Late Miocene shift to braided channels resulted from combined turbidity and contour currents， concurrent with basin-floor flattening and provenance change. New sediment input from the Paleo-Red River system (driven by Tibetan Plateau uplift) fueled this transition. Conclusively， the channel morphological transformation responded to coupled global sea-level fall and tectonically driven provenance shift. This framework links climate and tectonics to deep-water system evolution， aiding hydrocarbon exploration in similar reservoirs.