Delineation of sedimentary sub-basin and basement configuration based on the upward continuation filter and 2d and 3d modeling of gravity data (a case study: Rembang Area and its surroundings)

Abstract

East Java Basin is classified as a classical back-arc basin so that it is indicated that the basin has a complex structure and stratigraphy where there is an area called Rembang High. Rembang High is a gravity anomaly term that appears in Northern of East Java Basin area which has a higher value than other physiographic zone and is assumed to be associated with Rembang anticline. It is interesting to study the basement configuration and sedimentary sub-basin presumption. The gravity anomaly is supperposition of all anomaly sources in the subsurface, namely regional and residual anomaly. The separation of regional and residual anomaly is done by using upward continuation filter. Optimum continuity height can be obtained from the cross correlation of two continuity heights. The tesidual anomaly was obtained from the difference between Bouguer and regional anomaly. In addition to use the optimum continuity height, anomalous source depth estimation is obtained by using spectral analysis. The results obtained using both upward continuation and spectral analysis shows the same optimal depth value of 3500 meters or 3.5 kilometers. 2D and 3D modeling is done to facilitate the interpretation of the condition of geological structures below the surface. The modeling result shows the existence of rocks that are raised (basement high) at a depth of 3.5 kilometers and basin depocenter at a depth of 5 kilometers with a basement which is assumed as a metasediment rock has > 2.7 g/cm3 density.