Abstract:
It was discovered that there existed two classic types of carbonate cycle, namely, Atlantic type and Pacific type, in the late Quaternary sediments in the South China Sea. In this paper, some characteristics of carbonate cycles in the South China Sea and the sea area southeast of Taiwan were discussed using the data of
δ18O, CaCO
3 content, Al
2O
3 content, SiO
2 content, planktonic foraminireral abundance, and calcareous nannofossil abundance. These data were derived from thirteen cores. Generally, CaCO
3content and SiO
2 content are good proxies for the representation of carbonate cycles, and these two variables often display inverse relationship. In the study area, the types of carbonate cycle include not only the classic Atlantic and Pacific types, but also irregular forms. The Atlantic- type carbonate cycle is intimately related to sea level fluctuation in the glacial- interglacial cycle, and the studied cores with this type cycle are mainly located in the region whose water depth is less than 3000 m in the South China Sea. The Atlantic-type carbonate cycle on the north slope of the South China Sea was likely accompanied by the enrichment process of coarser (finer) particles during the periods of sea level descent (rise). The cores featured by Pacific- type carbonate cycle in the South China Sea are distributed within a big depth range across the modern calcite lysocline, which suggests that carbonate dissolution cycle was not the primary cause of the Pacific- type carbonate cycle. The carbonate cycle type of the studied core derived from the sea area east of Taiwan was neither Atlantic-type nor Pacific-type. The sedimentation rates of sub-bottom strata in the study area had little relationship with the types of carbonate cycle, but were deeply influenced by water depth and the glacialinterglacial sea level fluctuations. The sedimentation rates were increased with increasing water depth, and the average sedimentation rates during MIS2 was more than twice the ones during MIS1.