Data Trawler - Survey Details

IN2020_V01    - is a Marine National Facility voyage

Title: Development of William’s Ridge, Kerguelen Plateau: tectonics, hotspot magmatism, microcontinents, and Australia’s Extended Continental Shelf

Voyage details on MNF site: https://mnf.csiro.au/en/Voyages/IN2020_V01

Period: 2020-01-10 00:34 to 2020-03-06 00:00 UTC

Duration: 55.98 days

From: Fremantle To: Fremantle

Region: William's Ridge; Kerguelen Plateau; Australian Extended Continental Shelf; Southern Ocean; Antarctic Circumpolar Current; Broken Ridge

Ship: Investigator (RV) [details]

Description: RV Investigator research voyage in2020_v01 is titled “Development of William’s Ridge, Kerguelen Plateau: tectonics, hotspot magmatism, microcontinents, and Australia’s Extended Continental Shelf.”

The Indian Ocean contains numerous enigmatic topographic features, and some of the least understood are submarine ridges. This expedition will focus on William’s Ridge, part of Earth’s second largest submarine plateau, the Kerguelen Plateau, and on the once adjoining Broken Ridge. The voyage will acquire and analyse rock samples and geophysical data from these ridges to understand how they formed and evolved. The research will aim to resolve questions about the plate tectonics of the Indian Ocean, determine if William’s Ridge is a continental sliver, help understand massive volcanism triggered by mantle hotspots, and potentially contribute to expanding Australia’s sovereign undersea territory.

The two principle scientific objectives of the voyage are:
1. To gain important new knowledge of the rifting, breakup, and initial separation of tectonic plates. The project constitutes the first-ever case study of conjugate oceanic plateau end-members – the formerly contiguous and subaerial, but now separated and submarine Kerguelen Plateau and Broken Ridge in the southern Indian Ocean – to investigate these phenomena.
2. To acquire, analyse, and interpret data and samples necessary for Australia to make a new or revised submission to the UN Commission on the Limits of the Continental Shelf (CLCS). The purpose is to extend our marine jurisdiction to include William’s Ridge, an extension of the Central Kerguelen Plateau, under the UN Convention on the Law of the Sea (UNCLOS).

To address the scientific objectives of the project, the voyage objectives encompass acquiring and initially processing multibeam bathymetry/backscatter, water-column echo-sounding, sub-bottom profile, seismic reflection, deep-towed camera, gravity, and magnetic data acquisition; and acquiring rock samples by dredging. The acoustic data will be used to determine the locations of the seismic reflection profiles, and the acoustic and seismic data will be used to determine locations of dredging sites. The following activities will be undertaken:

1a. Multibeam bathymetry/backscatter: we will acquire multibeam data along William’s Ridge, the conjugate portion of Broken Ridge not covered by the MH370 search data, and associated seafloor topographic features.
1b. Sub-bottom profiling: we will acquire SBP120 data continuously multibeam data acquisition.
1c. Seismic reflection: we will utilise the MNF’s new seismic system, currently consisting of a 40-channel, 500-m-long, 12.5-m group spacing streamer and two GI airguns.
1d. Dredging: recovery of continental, hotspot-related, and/or oceanic rocks forming the basement of William’s Ridge and associated topographic features in the Labuan Basin, in multiple locations, is the goal, complemented by sampling the conjugate basement of Broken Ridge.
2a. Single-beam and multi-beam water column echo-sounding: we will collect EK60 and ME70 data throughout the entire voyage.
2b. Deep tow camera: on the basis of dredges and water column echo-sounding data, we will acquire still and video photography at locations characterized by mixed hotspot-related/oceanic/continental rocks and acoustic plumes emanating from the seafloor.
3a. Gravity: gravity data will be acquired by the shipboard gravity meter during the entire voyage. No modern shipboard gravity data have been acquired over William’s Ridge.
3b. Magnetics: we will acquire total magnetic field data using the towed proton precession magnetometer on the transits and throughout multibeam/sub-bottom profiling data acquisition.

For more information about the voyage objectives and projects please refer to the voyage plan.

Leader: Mike Coffin (UTAS)

Projects:

• Development of William’s Ridge, Kerguelen Plateau: tectonics, hotspot magmatism, microcontinents, and Australia’s Extended Continental Shelf [details] Primary

• Argo Float deployment [details] Supplementary

• Using samples from the Kerguelen Plateau to date past West Antarctic ice sheet collapse [details] Supplementary

• Southern Ocean Carbon Cycling Observations and Modeling (SOCCOM) Project [details] Piggy-back