Sedimentary fills and sensitivity analysis of deep lacustrine facies in multi-segment rift basins: Insights from 3D forward modeling

Abstract

This article presents a series of stratigraphic forward simulations of deep lacustrine sedimentary fills of continental multi-segment rift basins. These models integrate basin filling with the evolution of the extrabasinal catchment area, and relate tectonism and precipitation fluctuations to changes in lake level and sediment supply. The models reproduce the physical processes acting on the whole depositional environment from the site of erosion in the catchment area to deposition deep in the basin, and capture the complexity and variability of lacustrine rift basins. Results from these simulations show: (1) both extremely arid and extremely high-precipitation conditions are not favorable for the development of a large proportional volume of deep lacustrine facies in rift basins; (2) an increase of basin subsidence rate or a decrease of erosion rate in the source area increases both the proportional volumes of deep lacustrine sediment contained within the total rift fill and sand-rich sediment contained within deep lacustrine facies; (3) the development of deep lacustrine facies is more sensitive to basin subsidence and source erosion under very high-precipitation conditions; and (4) under various scenarios of basin subsidence and source area erosion, the proportion and style of deep-water sand accumulation is shown to be insensitive to climate conditions. Our simulations shed light on deep lacustrine fills in lacustrine rift basins and deepen the understanding of the influences of different conditions of evaporation-precipitation (from arid to humid), subsidence rates (e.g., reflecting end-member processes of continental extension), and erosion rates (e.g., reflecting varying bedrock terranes within the catchment), which help predict favorable conditions for the development of lacustrine source rocks and deep-water hydrocarbon reservoirs.