珠江三角洲晚第四纪地层、海平面变化 与构造运动的关系

在回顾南海北部海岸和陆架地层证据的基础上，梳理了珠江三角洲晚第四纪演变历史。结果显示：1）本区晚第四纪地层拥有2套海相沉积，上（新）海相层是当前间冰期（或10.5 ka B.P.以来）高海平面期间形成的沉积物，而下（老）海相层最可能是末次间冰期（126―120 ka B.P.）高海平面阶段留下的沉积物；2）老海相层顶面埋深在三角洲盆地内至少比现今海平面低10~15 m，在珠江口一带则低于20 m，这说明珠江三角洲盆地存在构造沉降，因为2次间冰期的海平面高度是相近的；3）在新生代欧亚板块大陆向东南伸展的构造格局下，南海北部陆架和海岸带经历长期连续的沉降，而长期平均沉降率在0.12 mm/a左右，明显低于GPS测出的现代沉降率；4）在这种板块运动基础上，晚第四纪断裂活动增强了三角洲盆地的沉降，为2次海侵提供了可容沉积空间。

Relationship between Late Quaternary Lithostratigraphy,Sea-level Change and Tectonics in the Pearl River Delta

Based on a review of the lithostratigraphic data from the coastal area and the continental shelf of northern South China Sea, this paper has examined the Late Quaternary evolutionary history of the Pearl River Delta. Results show that: 1) the deltaic basin of the Pearl River contains two marine sequences, the upper (younger) one belongs to the present interglacial (the past 10.5 ka B.P.) deposit and the lower (older) one most likely is that of the high sea level period during the last interglacial (126–120 ka B.P.); 2) the burial depth of the older marine sequence within the deltaic basin is recorded at 10-15 m below present sea level, whilst the depth in the mouth region is found below 20 m, implying geological subsidence because the height of sea level during the last interglacial was close to that of the present; 3) within the tectonic framework of southeastward continental extension of the Eurasian Plate during the Cenozoic, the coast and continental shelf of northern South China Sea has experienced a continuous subsidence at a long-term average rate of 0.12 mm/a, which is similar to that measured by GPS at present; 4) on top of the continental subsidence, fault activity has enhanced the localized subsidence of the deltaic basin, which led to the creation of accommodation space for marine inundation during interglacial high sea levels.