Evolution of a Normal Fault System Along Eastern Gondwana, New Zealand. Issue 10 (30th September 2020)

• Record Type: Journal Article
• Authors: Sahoo, T. R.; Nicol, A.; Browne, G. H.; Strogen, D. P.
• Is Part Of: Tectonics. Volume 39:Issue 10(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-09-30
• Subjects: Cretaceous rifting -- Zealandia -- Great South Basin; Geology, Structural -- Periodicals; 551.8
• DOI: 10.1029/2020TC006181
• Languages: English
• ISSNs: 0278-7407

Abstract

Abstract: The Great South Basin (GSB) developed in the Cretaceous from continental rifting at the southeastern margin of Gondwana. The basin contains a thick Cretaceous succession that is largely unaffected by Neogene compressional tectonics, with rift faults and associated growth strata imaged by good‐quality 2‐D and 3‐D seismic data tied to wells. These data show three distinct stages of normal faulting here referred to as fault system initiation (Stage 1), fault system growth (Stage 2), and fault system death (Stage 3). The different stages of fault system evolution comprise dominant NE trending faults (NW‐SE extension), and minor NW trending faults (NE‐SW extension). Fault initiation at ~105–101 Ma mainly occurred in the central GSB with rift depocenters mostly on, or close to, NW trending basement terrane boundaries. These preexisting basement boundaries represent zones of weakness that locally promoted early localization of NW faults and retarded the propagation of NE faults. With increasing regional extension and fault system growth from ~101 to 90 Ma the influence of the basement fabric gradually decreased, while NE trending faults increased in length, number, displacements, and spatial distribution. Finally, during the fault system death stage from ~90 to 83 Ma the length, number and displacements of faults decreased. Fault death coincided in time with Gondwana breakup and reflects the localization of extension along spreading centers distal to the GSB. Key Points: A regional seismic data interpretation in the Great South Basin revealed three stages of fault evolution over about 22 Ma Dominant fault set trends NE and minor fault set trends NW, with the latter forming along basement terrane boundaries Rift faulting is interpreted to reflect the embryonic stages of Gondwana breakup