Seismic Stratigraphy and Tectonic History of the Tasman Frontier

Abstract

A regional cooperation program between New Caledonia, New Zealand and Australia has led to the compilation of c. 100,000 line km of seismic reflection data from a continental region that covers an area of c. 3,000,000 km². We present a seismic stratigraphic chart at the scale of the southwest Pacific that summarises our interpretation of the dataset. Our new seismic stratigraphy regionally identifies five coherent mega-units. These mega-units record the tectono-stratigraphic evolution of the southwest Pacific from Mesozoic fragmentation of the eastern Gondwana margin to Cenozoic subduction and associated marginal sea development. Unit 3 corresponds to the Phanerozoic pre rift sedimentation along the Gondwana active margin; Unit 2a is the Cretaceous syn rift sedimentation related to the first stages of fragmentation of the Eastern Gondwana margin among which the opening of the Tasman Sea; Unit 2b corresponds to a passive post rift sag sedimentation; Unit 1b records the Eocene onset of regional compression and uplift interpreted to be related to the initiation of the Tonga Kermadec subduction zone and Unit 1a marks subsidence and a return to tectonic quiescence interpreted as the consequence of the slab roll-back of the Tonga-Kermadec subduction. This regional stratigraphic chart and associated geological events presents a new starting point for geodynamic studies of the SW Pacific as well as for local basin-scale studies.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015