琼东南盆地南部隆起带新生界沉积体系及其构造-沉积演化

新特提斯洋的弧后扩张导致古南海消亡与新南海扩张,西沙、中沙等微陆块从华南陆缘分离,使琼东南盆地形成并持续沉降。琼东南盆地南部隆起带崖城组沉积期以填平补齐为特征,主要发育近物源的扇三角洲-浅海陆棚沉积体系,物源主要来自松南低凸起和南部隆起剥蚀区。陵水组-梅山组沉积期,由于构造沉降叠加全球海平面上升使海侵扩大,南部隆起带主要发育浅海陆棚沉积,仅在西沙(永乐)隆起发育孤立碳酸盐台地(生物礁)。琼东南盆地及其南部隆起带新生代的构造-沉积演化是在古南海消亡与新南海扩张导致盆地持续沉降的构造背景下完成的,并叠加了全球海平面显著下降对滨海-浅海陆棚剥蚀夷平的强烈影响。

Cenozoic sedimentary systems and their tectonic-sedimentary evolution in southern uplift zone of the Qiongdongnan Basin

The back-arc spreading of the Neo-Tethys resulted in the consumption of the Palaeo-South China Sea and the spreading of the Neo-South China Sea. Subsequent separation of Xisha and Zhongsha microcontinental masses from the South China Continental margin gave rise to the formation and continuous subsidence of the Qiongdongnan Basin. During the deposition of the Yacheng Formation in the southern uplift zone of the Qiongdongnan Basin, the filling-up prevailed over the Basin, and then resulted in the development of the fan delta-shallow shelf sedimentary systems near the source areas. The principal source of detritus lay to the Songnan low uplift and the southern uplift denudational areas. Till the deposition of the Lingshui Formation-Meishan Formation, the combination of tectonic subsidence and global sea-level rising resulted in the expansion of the transgressions, and the development of the shallow shelf deposits in the southern uplift zone. The isolated carbonate platform organic reefs were once developed only in the Xisha (Yongle) uplift zone. The tectonic-sedimentary evolution of the Qiongdongnan Basin and its southern uplift zone took place under the tectonic background of the continuous subsidence of the Basin caused by the consumption of the Palaeo-South China Sea and the spreading of the Neo-South China Sea, as well as the strong influence of the global sea-level falling on the littoral-shallow shelf denudation and filling-up.