Relationship between lithofacies association series and sedimentary systems tract of deep water cenozoic basins in the continental shelf of Viet Nam

Abstract

There is a close relationship between lithofacies and systems tracts because both units are controlled by sea level changes and tectonic movement. The cyclical changes of sea level lead to periodical changes of lithofacies. Each cycle of change of sea level creates a sequence or a basic sedimentary cycle.
In fact, lithofacies composed of monofacies and doublefacies are the cells of the sedimentary sequence. At the same time, lithofacies association series will set up the depositional systems tracts (sedimentary lowstand systems tract, sedimentary transgressive systems tract, and sedimentary highstand systems tract).
However, seismic wave fields of coarse, chaotic reflections belonging to regression alternating with parallel horizontal wave fields or onlap structures which are formed when sea level rises are seen quite often in a seismic profile. This is explained as follows: in each sedimentary cycle controlled by eustatic change cycle there are usually sedimentary rhythms due to short oscillations of sea level.