Post-rift magma plumbing system in the northern Great South Basin, New Zealand

Abstract

Late Cretaceous magmatism has been widely documented in the Great South Basin (GSB) of New Zealand, which is mainly relevant to the Gondwana break-up (105–83 Ma) and the separation of Zealandia from Australia and Antarctica (83–66 Ma). However, the magma plumbing system in the GSB is still poorly understood. In this study, we used a high-resolution 3D seismic reflection data to investigate the igneous intrusions that developed in the northern part of GSB. These igneous intrusions occurred from ∼75 Ma to ∼58 Ma that corresponded to the spreading of the Tasman Sea and the Southern Ocean. Most of the igneous intrusions developed above listric faults which formed during rifting stage. Moreover, dykes are also observed between the listric faults and igneous intrusions. Listric faults, dykes and sills formed the magma plumbing system of GSB. This study explored the possible origin of post-rift magmatism in the GSB, and addressed the post-rift magma plumbing system in detail, which greatly promoted the understanding of GSB’ evolution, resource exploration and marine geological hazard assessment.