Structure and evolution of the Kapuni Anticline, Taranaki Basin, New Zealand: Evidence from the Kapuni 3D seismic survey

Styles of deformation and timing of tectonic events documented by the Kapuni 3D seismic survey provide important constraints on models for the structural evolution of the Taranaki Basin. Two‐way travel time and seismic attribute maps of this survey reveal a large degree of structural complexity and a pronounced vertical change in structural style. Taranaki Basin stratigraphy has, to a large extent, been controlled by distinct tectonic events resulting in discrete seismostratigraphic units being recognised in the Kapuni area. Seismic units 3 and 2 represent coals, shales, siltstones, and sandstones of the Eocene Kapuni Group and bathyal mudstones and turbidite sandstones of the Oligocene‐middle Miocene Ngatoro and Wai‐iti Groups, respectively. Their bulk strain can be described as triaxial oblate flattening in response to east‐west‐oriented compression during the late Eocene‐late Miocene. The overlying seismic unit 1 represents sandstones, siltstones, and mudstones of the late Miocene‐Pleistocene Rotokare Group. Its structure is dominated by a dense array of left‐stepping oblique‐slip normal faults that originated from Pliocene‐Pleistocene oblique extension/dextral transtension and are possibly detached from seismic units 2 and 3 by an inclined detachment surface that cuts stratigraphically deeper from northeast to southwest.