Modern fine-grained sedimentation—spatial variability and environmental controls on an inner pericontinental shelf, Hong Kong

Fine-grained sediments in Hong Kong form part of an extensive cover that extends from nearshore locations to the mid-continental shelf. This featureless mud blanket is associated with sediment inputs from the Pearl River and has generally been considered to be homogeneous in its characteristics. However, detailed sedimentological and geochemical analyses have revealed that the superficial deposits show systematic spatial variations that reflect contrasts in deposition between the Pearl River Estuary to the west and fully marine conditions to the east. Results indicate significant differences in particle size, accumulation rates, biogenic silica, organic carbon content, C/N ratios, and stable carbon and nitrogen isotopes that reflect location with respect to the Pearl River Delta. Calcium carbonate content varies widely, tending to be higher close to land. Major controls over spatial variability include rainfall patterns and the supply of estuarine suspended particulate matter; the effects of palaeotopography and modern water depth; resuspension induced by monsoon winds and typhoons; and human impacts on the sea floor.