我国沿岸晚第四纪砂坝-泻湖体系的沉积模式

我国沿岸晚第四纪砂坝-泻湖体系可以分为海侵型、海退型、稳定型和局部海侵型,其理想分布模式为:海侵型分布于大陆架至冰后期最大海侵线之间的沉积层下部;海退型形成于最大海侵线至现代海岸线之间全新世沉积层上部;稳定型则出现在最大海侵线附近的狭窄地带。我国海岸线通过构造沉降带和隆起带,沉降带接受大量河流输沙,为多种砂坝-泻湖沉积体系准备了条件.隆起带沿岸沉积物来源贫乏,主要发育稳定型和局部海侵型砂坝-泻湖体系.

The Stratigraphic Model of the Late-Quaternary Barrier-Lagoon Depositional Systems Along the Coast of China

According to the stratigraphic position, depositional facies relationships and mode of formation, the late-Quaternary barrier-lagoon depositional systems along the coast of China can be classified into four types: 1 transgressive; 2 regressive; 3 stable; and 4 locally transgressive. On vertical section, the transgressive barrier-lagoon system occurs in the lower part of the sediment layers between the continental shelf and the boundary of maximum transgression; the regressive type occurs in the upper part of the Holocenc strata between the boundary of maximum post-glacier transgression and the present coastal line; the stable type occurs in the narrow zone near the maximum transgressive limit, which constitute ideal distribution model of various barrier-lagoon system. The coast of China cuts across the tectonic uplift and the subsidence belts. More than 90 percent of the total riverine sediments discharge into the subsidence belt forming broad coastal plain and thick depositional layers, which provides favorable conditions for the developing and preservation of ideal distribution model of barrier-lagoon systems. In the uplift belt, due to the poor sediment supply, stable and local transgressive types tend to be developed. The optimistic site for the development of barrier-lagoon system lies in the transitional area between the uplift belt and subsidence belt.