FORWARD SEDIMENT MODELING OF CARBONATE PLATFORM GROWTH AND DEMISE, EAST JAVA BASIN: EXAMPLE NORTH MADURA.

摘要

Interactions between tectonism, eustasy, carbonate accumulation rate, and environmental stresses impact the nucleation, growth, and demise of carbonate platforms. Some of these processes are evaluated using a process-based forward sediment modeling program (CARB3D~+) to simulate the evolution of a Miocene carbonate platform from the East Java Basin. Seismic discontinuity time slices flattened on the base of this platform show that the platform originated from seven nucleation mounds (400 to 1200 m diameter). The mounds grew concentrically and amalgamated to form a single isolated platform (7 km diameter, 360 m thick). The platform top is a high amplitude seismic reflector, marking the interface between the carbonate platform and overlying clastic interval. Subsidence and eustatic sea-level, depth-dependent carbonate production and the direction and speed of the principle wind and current served as input parameters for a forward sediment model that mimics the evolution of platform geometry seen in seismic. Based on the specified sea level curve, a reduction in growth rate such as would be expected in response to increased environmental stress is required to drown the platform. This suggests the demise of the platform may have resulted from the interaction between increased accommodation and environmental stresses lead to a dominance of slower-growing organisms. This methodology of incorporating seismic visualisation and forward sediment modeling with an understanding of the depositional system provides insights into the growth and demise of carbonate platforms.