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

conference contribution
posted on 2023-05-25, 00:22 authored by Watson, SJ, Mike CoffinMike Coffin, Joanne WhittakerJoanne Whittaker, Vanessa LucieerVanessa Lucieer, Jodi FoxJodi Fox, Rebecca CareyRebecca Carey, Arculus, RJ, Andrew BowieAndrew Bowie, Zanna ChaseZanna Chase, Robertson, R, Smith, T, Cooke, F
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.

History

Publication title

American Geophysical Union Fall Meeting abstracts

Pagination

V43F-08

Department/School

Institute for Marine and Antarctic Studies

Event title

American Geophysical Union Fall Meeting

Event Venue

San Francicso, USA

Date of Event (Start Date)

2016-12-12

Date of Event (End Date)

2016-12-16

Repository Status

  • Restricted

Socio-economic Objectives

Assessment and management of terrestrial ecosystems

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