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This study investigates the stratigraphic evolution of the Late Oligocene - Early Miocene carbonate platforms of the Yadana area (offshore Myanmar). Well data, regional 2D and local 3D seismic surveys allow the identification of three shallow-water carbonate platforms (Yadana, 3DF and 3DE) showing various morphologic and stratigraphic patterns influenced by the presence of a paleohigh. The identification of seven seismic sequences in the Yadana area constrains the stratigraphic evolution in three stages: (1) development of aggrading attached and isolated platforms during the Chattian; (2) a period of platform emersion during the Oligocene - Miocene transition; (3) drowning of the smaller buildup (3DE) associated with km-scale backstepping on the large platforms (3DF and Yadana) during the Aquitanian. The Aquitanian marks the onset of renewed volcanic activity associated with the development of fringing carbonate reefs during the Burdigalian. The rapid (∼6 My) development of these wide (∼5–70 km) and thick (∼300–850 m) carbonate platforms has been mainly controlled by the subsidence. However, the results highlight a strong overprint of eustatic fluctuations on the rates of change in accommodation, and hence on the stratigraphic architecture of the carbonate platforms. Based on an alternative model for the Cenozoic geodynamic evolution of the Yadana area, our results suggest that the platforms developed on a volcanic ridge of hotspot origin located in the Indian Ocean and not on a volcanic arc. Subduction jump processes are interpreted to have played a key role in the demise of all platforms by drastically changing the paleoenvironmental conditions during the Early Miocene, and led to the present-day location of the Yadana Ridge in a back-arc setting. The carbonate platforms from the Yadana area are thus a representative example of the interplay between global mechanisms and local paleoenvironmental parameters on carbonate platform initiation, growth and demise.

During the Plio-Quaternary, the Bonaparte Basin is characterized by a very wide (> 600 km, > 370 mi) carbonate platform and 200 km-wide (125 mi-wide) intra-shelf basin (the Malita ISB). Using 3D and 2D seismic data combined with exploration well data, this study characterizes the stratigraphic evolution of the Malita ISB during the last 3.5 million years. Two third-order transgressive sequences can be distinguished. A late Pliocene transgression occurred over an irregular topography resulting from the flexural reactivation of the Malita graben. In the centre of the intra-shelf basin, carbonate aggradation resulted in the formation of isolated carbonate platforms separated by deeper water seaways and inter-platform areas. Wider and more numerous carbonate platforms developed on the edges of the intra-shelf basin. During the late Quaternary, renewed flexural deformation initiated a second transgressive cycle marked by higher subsidence rates in the ISB centre than along its edges. High rates of accommodation creation (at third-order) combined with higher-frequency (fourth-order), high-amplitude fluctuating sea levels and increased clastic input resulted in the progressive demise and burial of the carbonate platforms in the ISB centre. Thus, the Plio-Quaternary stratigraphic architecture of the Malita ISB is strongly controlled by differential subsidence that controls spatial distribution of accommodation and ultimately platforms architectures.The Malita ISB constitute a rare recent analogue for Paleozoic and Mesozoic hydrocarbon-bearing intra-shelf basins.

During the Plio-Quaternary, the Bonaparte Basin is characterized by the development of a wide (up to 200km) intra-shelf basin (the Malita ISB) evolving under conditions of low tectonic activity. Based on 3D and 2D seismic surveys combined with exploration well data, this study demonstrates that the stratigraphic organisation of the Malita ISB is mainly driven by fluctuations of the relative sea-level. It can be divided in three main 3rd-order system tracts: (1) a transgressive system tract, corresponding to a period of active carbonate aggradation during the late Pliocene, (2) a highstand system tract, associated with a period of strong carbonate progradation during the early-middle Quaternary, and; (3) a last system tract phasing late Quaternary high-frequency fluctuations of the accommodation space, and associated with backstepping and progressive burial of most of antecedent carbonate platforms by mixed siliciclastic/carbonate sediments. In detail, 3D seismic stratigraphy and geomorphology analysis reveals that the mixed sedimentary system of the Malita ISB is also associated with higher-order sequences, marked by phases of carbonate growth during 4th to 5th order transgressions and highstands, while tide-dominated shallow water deposits accumulate during 4th – 5th order lowstands. Throughout the late Pliocene and up to the middle Quaternary, periods of lower sea-levels were associated with widespread tidal and fluvial incisions across the intra-shelf basin, resulting in a complex stratigraphic architecture in the inter-reef areas. Our findings clearly indicate that the well constrained Plio-Quaternary evolution of the Malita ISB represents an outstanding analogue to improve the knowledge of ancient intra-shelf basin depositional settings, which frequently coincide with prolific hydrocarbon systems.