Seismic Geomorphology of the Early and Late Miocene Carbonate Systems in an Active Tectonic Margin, Offshore East Java, Indonesia

Abstract

We utilized seismic geomorphology techniques to study 1300 km² of 3D seismic data from the West Madura Offshore (WMO) block, offshore East Java, Indonesia. The study area situated along the back-arc of the Java subduction zone. We characterized two carbonate systems in the Early and Late Miocene that show completely different geomorphic features. Depositional sequences without extensive carbonate buildups development around Middle Miocene separated the two systems.

The carbonate systems in the study area have evolved from a system in the Early Miocene characterized by circular to elongated (WSW-ENE) isolated carbonate buildups, which are smaller in dimension (hundreds of meters to several kilometers in width/length) to a system in the Late Miocene characterized by flat-topped carbonate platforms, mostly elongated in N-S orientation, which are significantly larger (several kilometers in width, tens of kilometers in length). Each of these carbonate systems can reach a total thickness of around 1100-1200 feet.

We delineated approximately 149 isolated carbonate buildups that cover a total area of 180 km² in the Early Miocene interval and eight carbonate platforms that cover a total area of 400 km² in the Late Miocene. We observed a clear correlation between the distribution pattern of the Early Miocene carbonate buildups and the NE-SW orientation of the basement high (the JS-1 Ridge). On the contrary, the distribution of the Late Miocene carbonate platforms does not show major influence of antecedent topography. Features such as flat-topped geometry, margins progradation, and sinuous channels development on top of the youngest part of the Late Miocene carbonate platforms strongly imply decreasing accommodation related to regional compression and tectonic inversion during a period of relatively low amplitude of eustatic sea-level fluctuation.

This study suggests that the combination of tectonic convergence and eustasy demonstrated strong influence on the spatio-temporal variation of depositional geometries, distribution, and development of carbonate buildups/platforms in the Miocene carbonate systems. A better understanding of the carbonate systems development in this study will contribute to the regional and global knowledge. Ultimately, this study aims to provide valuable insights to better predict the geometry, architecture, and distribution of the carbonate reservoirs situated in a tectonically active region.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018