Holocene Sedimentary Architecture of the Red River Delta, Vietnam

Abstract

Remotely sensed satellite images, integrated with compilations of shallow geological data, enable elucidation of the Holocene facies architecture of the Red River Delta of Vietnam. The Holocene delta sediments are relatively finegrained, up to 30 m thick, and represent rapid progradation during the current high sea level stand; they overlie a coarse-grained Pleistocene sequence of braided river and alluvial fan deposits formed during glacial low sea level stands. The Holocene delta shows roughly equal influence by fluvial, wave and tidal processes. In this it resembles the Niger Delta, but with the crucial difference that the facies belts are sectorial rather than concentric, being governed along the coast by differing amounts of shelter from wave action in a uniformly mesotidal setting. The wave-dominated sector appears to have advanced by 'leapfrogging' seawards, perhaps under the influence of episodic high-discharge fluvial flood events, producing lateral alternations of stacked sandy beach ridges and intervening fine-grained lagoonal deposits in chenier-like architectures.