HR: 0800h
AN: OS31A-0165    [Abstracts]
TI: Marine Conglomerates of Agaete, Gran Canaria: A Tsunami Origin?
AU: * Austin-Giddings, W D
EM: w.austin-giddings@ucl.ac.uk
AF: Benfield UCL Hazard Research Centre, University College London Department of Earth Science Gower Street, London, WC1E 6BT, United Kingdom
AU: * Austin-Giddings, W D
EM: w.austin-giddings@ucl.ac.uk
AF: British Geological Survey, Kingsley Dunham Centre Keyworth, Nottingham, NG12 5GG, United Kingdom
AU: Tappin, D R
EM: drta@bgs.ac.uk
AF: British Geological Survey, Kingsley Dunham Centre Keyworth, Nottingham, NG12 5GG, United Kingdom
AU: McGuire, W J
EM: w.mcguire@ucl.ac.uk
AF: Benfield UCL Hazard Research Centre, University College London Department of Earth Science Gower Street, London, WC1E 6BT, United Kingdom
AU: Day, S J
EM: simonday_ucl@yahoo.co.uk
AB: Of all the deposits interpreted as having been emplaced by a tsunami, those draping hillslopes at high elevations on ocean island volcanoes have been most controversial. Here, we describe such a deposit from the Canary Islands, whose minimal post-emergence subsidence or uplift makes interpretation of the deposits less difficult than in other examples. We present a preliminary interpretation of marine sediments located at Agaete, on the north-east coast of Gran Canaria. Previously interpreted as the result of a sea level high-stand, these have recently been re-interpreted as having been deposited by a volcanically-sourced tsunami. Our re-examination indicates that of the alternatives, a tsunami origin is the more likely. The deposit occurs in exposures of limited lateral extent, attached to the walls of the Agaete valley, and may be traced up to elevations of 188m a.s.l. and two kilometres inland from the coast. The deposits are up to 2m in thickness and contain a diverse assemblage of volcanic clasts, a marine fauna and large beach-rock boulders. Two sedimentary units are identified, separated by a calichified soil horizon. Analysis of microfossils has yielded a variety of marine organisms including gastropods, bivalves, sharks teeth, echinoid spines and foraminifera. The evidence supports a tsunami origin for a number of the beds, whereas others may be attributed to flash floods. Dating of the deposits has not yet been undertaken, but the Güimar lateral collapse on the neighbouring island of Tenerife (age range between 32 Ka and 1.75 Ma) has been cited as a possible source.
DE: 3022 Marine sediments: processes and transport
DE: 3030 Micropaleontology (0459, 4944)
DE: 4500 OCEANOGRAPHY: PHYSICAL
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting