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Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands

Citation

Watson, SJ and Coffin, MF and Whittaker, JM and Lucieer, V and Fox, JM and Carey, R and Arculus, RJ and Bowie, AR and Chase, Z and Robertson, R and Smith, T and Cooke, F, Submarine geology and geomorphology of active Sub-Antarctic volcanoes: Heard and McDonald Islands, American Geophysical Union Fall Meeting abstracts, 12-16 December 2016, San Francicso, USA, pp. V43F-08. (2016) [Plenary Presentation]


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Abstract

Heard and McDonald Islands (HIMI) are World Heritage listed sub-Antarctic active volcanic islands in the Southern Indian Ocean. Built atop the Kerguelen Plateau by Neogene-Quaternary volcanism, HIMI represent subaerial exposures of the second largest submarine Large Igneous Province globally. Onshore, processes influencing island evolution include glaciers, weathering, volcanism, vertical tectonics and mass-wasting (Duncan et al. 2016). Waters surrounding HIMI are largely uncharted, due to their remote location. Hence, the extent to which these same processes shape the submarine environment around HIMI has not been investigated.

In early 2016, we conducted marine geophysical and geologic surveys around HIMI aboard RV Investigator (IN2016_V01). Results show that volcanic and sedimentary features prominently trend east-west, likely a result of erosion by the eastward flowing Antarctic Circumpolar Current and tidal currents. However, spatial patterns of submarine volcanism and sediment distribution differ substantially between the islands. >70 sea knolls surround McDonald Island suggesting substantial submarine volcanism. Geophysical data reveals hard volcanic seafloor around McDonald Island, whereas Heard Island is characterised by sedimentary sequences tens of meters or more thick and iceberg scours - indicative of glacial processes. Differences in submarine geomorphology are likely due to the active glaciation of Heard Island and differing rock types (Heard: alkali basalt, McDonald: phonolite), and dominant products (clastics vs. lava). Variations may also reflect different magmatic plumbing systems beneath the two active volcanoes (Heard produces larger volumes of more focused lava, whilst McDonald extrudes smaller volumes of more evolved lavas from multiple vents across the edifice).

Using geophysical data, corroborated with new and existing geologic data, we present the first geomorphic map revealing the processes that shape the submarine environment around HIMI.

Item Details

Item Type:Plenary Presentation
Keywords:submarine geology
Research Division:Earth Sciences
Research Group:Geology
Research Field:Marine Geoscience
Objective Division:Environment
Objective Group:Ecosystem Assessment and Management
Objective Field:Ecosystem Assessment and Management of Marine Environments
Author:Watson, SJ (Ms Sally Watson)
Author:Coffin, MF (Professor Mike Coffin)
Author:Whittaker, JM (Dr Jo Whittaker)
Author:Lucieer, V (Dr Vanessa Lucieer)
Author:Fox, JM (Ms Jodi Fox)
Author:Carey, R (Dr Rebecca Carey)
Author:Bowie, AR (Associate Professor Andrew Bowie)
Author:Chase, Z (Associate Professor Zanna Chase)
ID Code:113602
Year Published:2016
Deposited By:Centre for Ecology and Biodiversity
Deposited On:2017-01-09
Last Modified:2017-01-10
Downloads:0

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