南海北部陆坡古地貌特征与13.8Ma以来珠江深水扇

综合利用层序地层学和地球物理方法对珠江口盆地白云凹陷13.8 M a以来沉积古地貌进行了分析。通过对南海珠江深水扇系统分布及其独特的沉积特征和层序充填演化规律的分析,得出在13.8 M a以来层序发育过程中,凹陷位于宽阔陆架向海盆变迁的陆坡区,北部发育两种类型的峡谷水道,向南海盆方向逐渐变得宽缓;盆地的古地貌背景、物源和气候变化为其主控因素的结论。同时,13.8 M a以来南海北部陆坡深水区的沉积具有明显的继承性特点,现今的海底峡谷发育特点基本反映了整体的沉积背景。结果表明,白云凹陷13.8 M a以来的深水沉积受海平面相对变化的影响相对较弱,主要受古地貌背景及其变迁的控制,沉积具有继承性,与现今的沉积面貌非常相似。

Northern Continental Slope Palaeogeomorphology and Deep-water Fan System Response of Pearl River Since 13.8Ma, South China Sea

Implied integrated sequence stratigraphy and geophysical method to analyze the 13.8Ma palaeogeomorphology of Baiyun sag, Pearl River Mouth Basin(PRMB). Submarine fan systems distribution,deposit characteristics and sequence stratigraphy filling evolvement analysis on sequence development from 13.8Ma implied that Baiyun sag lies in wide-slow continental shelf's slope area and develop two types canyons/channels on the north shelf margin , that Baiyun sag became to flat and open, and that submarine fan deposition are mainly controlled by palaeogeomorphology、sediment supply and fluctuation of climate. At the same time, north of South China Sea continental slope deepwater area’s depositional topography has been similar characteristic from 13.8Ma to today, and today’s submarine valley topography by and large implicated depositional paleo-geomorphology environment. It is concluded that deepwater deposition, which are mainly controlled by paleo-topography and evolvement rather than sea level changes, had been similar depositional topography character with today.