Stratigraphic architecture of Solander Basin records Southern Ocean currents and subduction initiation beneath southwest New Zealand

• Published in: Basin Research
• Main Authors: Patel, Jiten, Sutherland, Rupert, Gurnis, Michael, Van Avendonk, Harm, Gulick, Sean P. S., Shuck, Brandon, Stock, Joann, Hightower, Erin
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley 2021
• Subjects: Antarctic Circumpolar Current; Fiordland; Puysegur; Subductionâ€related basins; Subtropical Front; tectonics and sedimentation; Antarctic; New Zealand; Solander Trough; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://doi.org/10.1111/bre.12473

Solander Basin is currently characterised by subduction initiation at the Pacificâ€Australia plate boundary, where high biological productivity is found at the northern edge of the Antarctic Circumpolar Current. Sedimentary architecture results from tectonic influences on accommodation space, sediment supply, and ocean currents (via physiography); and climate influence on ocean currents and biological productivity. We present the first seismicâ€stratigraphic analysis of Solander Basin based on highâ€fold seismicâ€reflection data (voyage MGL1803, SISIE). Solander Trough physiography formed by Eocene rifting, but basinal strata are mostly younger than ~17 Ma, when we infer Puysegur Ridge formed and sheltered Solander Basin from bottom currents, and mountain growth onshore increased sediment supply. Initial inversion on the Tauru Fault started at ~15 Ma, but reverse faulting from 12 to ~8 Ma on both the Tauru and Parara Faults was likely associated with reorganization and formation of the subduction thrust. The new seabed topography forced sediment pathways to become channelized at low points or antecedent gorges. Since 5 Ma, southern Puysegur Ridge and Fiordland mountains spread out towards the east and Solander Anticline grew in response to ongoing subduction and growth of a slab. Solander Basin had high sedimentation rates because: (1) it is sheltered from bottom currents by Puysegur Ridge; and (2) it has a mountainous land area that supplies sediment to its northern end. Sedimentary architecture is asymmetric due to the Subtropical Front, which moves pelagic and hemiâ€pelagic sediment, including dilute parts of gravity flows, eastward and accretes contourites to the shelf south of Stewart Island. Levees, scours, drifts, and ridges of folded sediment characterize western Solander Basin, whereas hemiâ€pelagic drape and secondary gravity flows are found east of the meandering axial Solander Channel. The highâ€resolution record of climate and tectonics that Solander Basin contains may yield excellent sites for ...