Cenozoic morphological evolution of the Tanintharyi Shelf carbonate platform, Andaman Sea Basin: Implications for hydrocarbon reservoir potential

The Tanintharyi Shelf in the Andaman Sea Basin hosts a significant yet largely underexplored Cenozoic carbonate platform with substantial hydrocarbon potential. This study utilizes an integrated analysis of high-resolution 2D and 3D seismic reflection data, well data, and regional stratigraphic information to elucidate the morphological evolution of this platform and assess its implications for hydrocarbon reservoirs. The findings reveal that the platform started in the Early Miocene as isolated patch reefs on fault-bounded structural highs, eventually evolving into an asymmetric, westward-dipping rimmed shelf. Its development was influenced by the interaction of syn-sedimentary tectonics, which created accommodation space and a paleotopography that shielded the shelf from clastic influx, along with eustatic sea-level fluctuations that caused cycles of sediment buildup, subaerial exposure (leading to karstification), and back-stepping. Ultimately, the platform was drowned and buried during the Middle to Late Miocene due to accelerated post-rift subsidence combined with increased siliciclastic input, the latter driven by the Neogene uplift of the Tibetan Plateau. The reservoir potential varies across the platform, with the highest concentrations in wave-resistant reefal margin facies and potential dolomitized zones on paleo-highs, where primary porosity was enhanced by meteoric diagenesis. However, reservoir quality is compartmentalized due to tight cementation and mud-rich intervals. The widespread presence of gas chimneys and pockmarks indicates that the platform functions both as a reservoir and a conduit for fluid migration. Therefore, this study establishes a predictive tectonostratigraphic framework, emphasizing that successful exploration in this complex environment requires high-resolution mapping of facies boundaries, diagenetic features, and fault architecture, combined with seal integrity analysis. The findings offer a new model for understanding the evolution of carbonate reservoirs in tectonically active, rift-margin settings worldwide.