A seismic stratigraphic model for understanding the sedimentary and tectonic evolution of Solander Trough, offshore Fiordland, New Zealand

• Main Author: Patel, Jiten
• Other Authors: Sutherland, Rupert
• Format: Master Thesis
• Language: English
• Published: Victoria University of Wellington 2019
• Subjects: Basin evolution; Sedimentation; Tectonics; Basin research; Sedimentology; Antarctic; Ewing; Langseth; Maurice; New Zealand; Pacific; Solander Trough; The Antarctic; Antarc*
• Online Access: http://researcharchive.vuw.ac.nz/handle/10063/8508

Solander Trough is located offshore and south of Fiordland, New Zealand, adjacent to the geologically young Pacific-Australian plate boundary. Petroleum industry exploration was restricted to the near-shore. This thesis presents the first stratigraphic analysis of Solander Trough south of ~46.5°S, using 2D seismic reflection data acquired and processed onboard the R/V Marcus G. Langseth in 2018 (voyage MGL1803). The only pre-existing high-quality line, which was acquired onboard the R/V Maurice Ewing during voyage EW9601a in 1996, was reprocessed. The study area is divided into northern and southern sub-basins by Tauru High. Four megasequences and eight sequences are identified in the northern sub-basin (SLN). In the southern sub-basin (SLS), three megasequences and seven sequences are mapped. Biostratigraphy from the Parara-1 exploration well enabled age determination in the northern sub-basin. High resolution (~10 m) swath bathymetry data collected along seismic reflection lines provide insight into modern sedimentary processes. Solander Trough formed in the Eocene, but most sediment is young (<~15 Ma). Puysegur Ridge formed in the Miocene during subduction initiation and now shelters Solander Trough from the Antarctic Circumpolar Current, which affects depositional architecture. The oldest megasequences, SLN1 and SLS1, relate to normal-faulted basement with irregular relief. An increase in sediment supply from the north created megasquence SLN2, but it is thin and not recognised in the southern sub-basin. Megasequence SLN3 signals reverse reactivation on the Parara Anticline and Tauru High; its equivalent (SLS2) marks the first sediments rapidly deposited in southern Solander Trough, and is also linked in the south to initial growth of Puysegur Ridge. SLN4 is a product of Pliocene-Quaternary reverse reactivation of Solander Anticline, and its correlative, SLS3 in the southern sub-basin, is related to folding and widening of the eastern margin of Puysegur Ridge.