A review of the Gippsland Basin history based on comparison of 3D structural, stratigraphic and forward sedimentation models: recognition of source, reservoir, traps and canyons.

The tectono-sedimentary history of Gippsland Basin from the Early Cretaceous to present was modelled using Badlands landscape software constrained by a 3D structural and stratigraphic Petrel model. The aim is to assess the theoretical sedimentary models using empirical data to better understand the sedimentary history for this rift basin. The models measure the relative effects and most significant variables for basin evolution, including climate, deposition and erosion with extension, subsidence, uplift and eustacy. They show how the detailed basin landscapes evolved and provide new insights to understand facies development in the basin. Early Cretaceous paleotopography ca 137 Ma had extensive highland areas to north, east and south of a rapidly subsiding intracratonic rift with sediment transport east to west. The simulated paleoenvironments are alluvial and fluvial with floodplain lakes developing into extensive lake systems further west. The mid-Cretaceous uplift changed basin architecture, initiating the Strzelecki Ranges and regional erosion. Tasman Sea rifting in early Late Cretaceous formed the Central Deep further east and flipped the paleodrainage eastwards. Latrobe Group sediments filled this smaller depocentre to the east starting with rapidly deposited very thick intracratonic fluvial and lacustrine sediments becoming more coastal plain and shallow marine up section, with Emperor, Golden Beach and Halibut subgroups containing reservoirs and potential source rocks for petroleum. Rising sea-levels in the Late Cretaceous transgressed most of the Latrobe Group by the Oligocene. Simulations from Oligocene to Holocene show less extensive non-marine deposition onshore with incised valleys and very thick coals, while a widespread carbonate shelf built and prograded offshore, periodically cut by submarine canyons. Scenario analysis for 13 variables shows that no single factor is the main control on rift basin evolution; rather basin history is shaped by interactions between climate, uplift, erosion, subsidence and deposition. These controls usually balance sea-level except where it changes rapidly. Numerical tectono-sedimentary basin history reconstruction constrained by empirical data requires a balance of uplift, sediment supply and subsidence. Paleolandscape simulation in the Gippsland Basin from Early Cretaceous to present-day shows how the detailed facies distribution changed with time. New potential reservoirs and source rocks are recognised within the Cretaceous Strzelecki Group, Emperor and Golden Beach subgroups. Organic-rich Turonian source rocks were deposited in restricted lacustrine intra-rift settings. [ABSTRACT FROM AUTHOR]