Seismic architecture of a Miocene isolated carbonate platform and associated off-platform strata (Central Luconia Province, offshore Malaysia)

Abstract

Abstract Rather than being homogeneous and isotropic, many isolated carbonate platforms in the geologic record include internal heterogeneity and complex geometric relations with off-platform strata on their flanks. To better understand stratal architecture of a Miocene isolated platform (Central Luconia, offshore Malaysia), this study integrates core, log and seismic data, revealing stratal terminations and geometries that define several seismic stratigraphic units. A thick in the basal seismic unit, the initial deposits of the carbonate buildup, is 4–5 km across. This thick includes abrupt thinning to the west and east, with onlap onto its flanks, but continues outside of the survey area to the north and south. Above a mappable surface, a less extensive (2 × 5 km) seismic unit represents a backstepped isolated platform (Platform Stage 1). Across a pronounced normal fault on the east/southeast margin of the platform occur marked isochron and seismic character changes, with thicker carbonates on the downthrown (western) block. The northern and western margins are not faulted. A third seismic unit, representing a smaller, elongate ( The most marked stratigraphic theme within the isolated platform is the successive backsteps, but the pattern is complicated by interactions with the basinal strata. Superposition and cross-cutting relations document that isolated platform-sourced flanking beds (”wings”) interfinger with basinal clinoforms (”wedges”), as defined by geometries on the margins and flanks of platform stages. The platform evolution also was influenced markedly by syndepositional structural activity, although structural trends changed from the initial buildup to later platform stages. The results, and comparison with other isolated platforms, demonstrate the complex controls on carbonate platform growth and interactions with basinal siliciclastics.