Structural and Stratigraphic Evolution of the East Java Sea, Indonesia

Abstract

Abstract The East Java Sea displays excellent examples of Miocene to Present-Day structural inversion of a Palaeogene extensional/transtensional basin system. The structural geometry of these inversions has been analysed by a series of regional cross-sections which demonstrate significant lateral variation in structural style. This variation is interpreted to be a function of the fault shape and linkage which evolved during the extensional phase of basin development. Prediction of fault geometry has been aided by analogue-modelling of inverted extensional basins. Driving mechanisms of structural inversion have been assessed by modelling the motion of the Eurasian, Indian Ocean, Australian and Pacific plates during the Neogene. The evolution of inversion within the East Java Sea is interpreted to be a function of the propagating collision of the Australian Plate with the Sunda Arc, and the resultant variation in relative convergence rate and direction of the subducting Indian Ocean Plate and the S.E. Eurasian Plate. Stratigraphic evolution is strongly influenced by relative sea level fluctuations, principally eustatic, within overall control of tectonic processes, particularly inversion. The sediment fill is mainly fine-grained with alternating carbonate-dominated and clastics-dominated cycles. The use of wireline logs, seismic data and biostratigraphic data allows a detailed sequence stratigraphy to be developed, with both regionally and locally recognisable highstand, lowstand and transgressive systems. A well-imaged progradational carbonate platform margin exhibits late-stage growth and subsequent inundation which are used to calibrate locally derived relative sea-level curves.