Statistical Analysis of Dispersion and Geochemical Patterns
of Sedimentary System in Northern Shelf of the South
China Sea
DiZhou
1
Introduction
The northern shelf of the South China Sea is the site of dispersion for a large
quantity of discharges from the Southeast China continent. Today, the shelfborders the most prosperous economic zone in China; it is also the site of a flourishing development of the Chinese marine industry, including offshore petroleum
exploration and exploitation, fishery, aquaculture, and shipping. This chapter
presents a statistical analysis of dispersion and geochemical patterns of the seafloor sediments of the shelf based on data accumulated during the period 19641975. Thus the patterns represent the background configuration of the area with
respect to the present patterns; the latter may be contaminated by the fast economic development in the area since the mid 1980s.
2
Study Area
The South China Sea is a tropic marginal sea of the West Pacific. It covers over
17° latitude, with a total area of 3.S x 10 6 km 2 • The surface water of the sea has a
temperature of 19-29 °C in winter and 27-31 °C in summer, and a salinity of 3134%0 in the open sea and of 28-1S% near river mouths. The water circulation of
the South China Sea is controlled mainly by SE-Asian monsoon, which is northeasterly and strong in winter, but southwesterly and mild in summer.
The northern shelf of the South China Sea includes the sea area bordered by
the shelfbreak at about lS0-300 m water depths (Fig.I). It is the largest shelf of
the South China Sea, about lS0-31O km wide and 700 km long, gently dipping
southeastward with an average slope of about 0°03'-0°04'. The shelf widens
southwestward until it is blocked by Hainan Island.
A large portion of the central shelf is occupied by the underwater Zhujiang
River (Pearl River) delta system, wich mooves southeastward up to 200 m isobath. The system consists of four ancient deltas superimposed upon each other,
corresponding to four steps of terraces on the shelf, and indicating four stages
of sea level variations during Late Pleistocene to Quaternary (Feng et al. 1988).
A large quantity of land discharges are transported onto the shelf from the
Southeast China through numerous rivers. Among these the Zhujiang River
of Sedimentary System in Northern Shelf of the South
China Sea
DiZhou
1
Introduction
The northern shelf of the South China Sea is the site of dispersion for a large
quantity of discharges from the Southeast China continent. Today, the shelfborders the most prosperous economic zone in China; it is also the site of a flourishing development of the Chinese marine industry, including offshore petroleum
exploration and exploitation, fishery, aquaculture, and shipping. This chapter
presents a statistical analysis of dispersion and geochemical patterns of the seafloor sediments of the shelf based on data accumulated during the period 19641975. Thus the patterns represent the background configuration of the area with
respect to the present patterns; the latter may be contaminated by the fast economic development in the area since the mid 1980s.
2
Study Area
The South China Sea is a tropic marginal sea of the West Pacific. It covers over
17° latitude, with a total area of 3.S x 10 6 km 2 • The surface water of the sea has a
temperature of 19-29 °C in winter and 27-31 °C in summer, and a salinity of 3134%0 in the open sea and of 28-1S% near river mouths. The water circulation of
the South China Sea is controlled mainly by SE-Asian monsoon, which is northeasterly and strong in winter, but southwesterly and mild in summer.
The northern shelf of the South China Sea includes the sea area bordered by
the shelfbreak at about lS0-300 m water depths (Fig.I). It is the largest shelf of
the South China Sea, about lS0-31O km wide and 700 km long, gently dipping
southeastward with an average slope of about 0°03'-0°04'. The shelf widens
southwestward until it is blocked by Hainan Island.
A large portion of the central shelf is occupied by the underwater Zhujiang
River (Pearl River) delta system, wich mooves southeastward up to 200 m isobath. The system consists of four ancient deltas superimposed upon each other,
corresponding to four steps of terraces on the shelf, and indicating four stages
of sea level variations during Late Pleistocene to Quaternary (Feng et al. 1988).
A large quantity of land discharges are transported onto the shelf from the
Southeast China through numerous rivers. Among these the Zhujiang River