Distribution pattern and influence factors of benthic foraminifera in the surface sediments of northern South China Sea

Foraminifera is an important and sensitive environment indicator. To study the distribution pattern and influencing factors of the foraminifera in the modern environment is the key to the reconstruction of sedimentary environment in the past. South China Sea covers a vast area, researches on the modern foraminifera in that part of the South China Sea have been reported since a long time. Recently, more and more researches have been devoted to the change of foraminifera and its relation to the methane leakage in the South China Sea. However, few studies have been donated to the distribution of foraminifera in the modern environment of northern South China Sea. In this study, we carefully described the distribution pattern of benthic foraminifera in the northern part of the South China Sea and discussed the factors affecting their distribution pattern. In the study area, the calcareous hyaline benthic foraminifera dominate, followed by the agglutinated benthic foraminifera and the calcareous porcelaneous benthic foraminifera. Four benthic foraminifera assemblages are recognized according to their distribution patterns, namely the assemblage 1: Heterolepa subpraecincta-Hanzawaia mantaensis- Rotalinoides gaimardii; the assemblage 2: Bulimina marginata-Lagena substriata; the assemblage 3: Elphidium advenum-Pararotalia nipponica; and the assemblage 4: Recurvoides contortus-Ammodisus cretaceous-Bulimina aculeata. Environmental factors, such as temperature, salinity, and substrate type in the northern part of the South China Sea all have influences on the distribution of benthic foraminifera to certain extent, and the influence of oceanic currents on the spatial and temporal distribution of benthic foraminifera deserves further investigation.