Inversion history of the northern Tasman Ridge, Taranaki Basin, New Zealand: implications for petroleum migration and accumulation

The northern Tasman Ridge in the southern Taranaki Basin is an entirely sub-surface inversion structure that hosts some of New Zealand's largest oil and gas field discoveries. Contiguous 3D volumes and 2D seismic reflection data tied to 26 exploration and production wells delineate 5250 km(2) of the northern Tasman Ridge enclosing the Maui, Maari and Manaia petroleum fields. Isopachs and structural restoration of Late Cretaceous to Pleistocene time equivalent horizons constrain the development of positive and subsequent negative inversion, extension and regional tilting. Positive inversion occurred synchronously along the northern Tasman Ridge 8-6 Myr ago with the magnitude of inversion decreasing northwards. Inversion anticlines across the Maui high were open to the northeast until the mid-Pliocene when negative inversion and extension were initiated along the Cape Egmont Fault. Pliocene - Holocene extension along the Cape Egmont Fault has tilted the Manaia and Maari inversion anticlines down to the north along with accentuating structural closure across the Maui high. In a fill to spill scenario, this north-down tilting resulted in spill points of the Maari structure changing from southwest into the Manaia structure to southeast towards the greater Tasman Ridge c. 2 Myr ago.