--> Seismic Stratigraphy of the Fairway Basin, Northern Zealandia, Southwest Pacific: Geodynamic and Petroleum Implications

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Seismic Stratigraphy of the Fairway Basin, Northern Zealandia, Southwest Pacific: Geodynamic and Petroleum Implications

Abstract

The Fairway Basin is situated between Australia and New Caledonia, in the northern Tasman Frontier area. This north-south-oriented basin is bordered by the Lord Howe Rise and the Fairway Ridge and lies within water depths ranging from less than 1,000 m up to 2,400 m. This basin formed through rift-related passive subsidence associated with eastern Gondwana breakup during mid-to-Late Cretaceous and received detrital and pelagic sediments since that time. It is notably known for a 80 000 km2 Bottom Simulating Reflector (BSR) interpreted as one of the world's largest gas hydrate layer or as a regional diagenetic front. Seismic reflection data reveal sedimentary thicknesses (up to 4 km) and geometries compatible with generation and entrapment of liquid and gaseous hydrocarbons. Seismic stratigraphy and available well data were used to reconstruct both the paleogeographic and tectonic evolution of the Fairway Basin. In particular, this work allowed the discovery of a deeply buried delta likely to be similar to the deep-water Taranaki Delta. This stratigraphic framework is used to constrain multi-1D generation modelling and to test two main hypotheses of source rocks. The most likely scenario, similar to the one accepted for the Taranaki Basin, is a type-III source rock intercalated in cretaceous prograding series. Another possible scenario is a source rock equivalent to the East Australian Walloon Formation and occurrence of marine source rock in the pre-rift sequence. Although large modelled volumes at this stage are speculative due to limited data on source rock composition, richness and distribution, as well as on the presence and quality of reservoir and seal, this study confirms the prospectivity of the Fairway Basin and the need for more data to further assess this basin.