HR: 1340h
AN: V33B-1381    [Abstracts]
TI: Crustal and Upper Mantle Structure Beneath the Canary Islands From Teleseismic Receiver Functions.
AU: Lodge, A
EM: a.lodge@liv.ac.uk
AF: University of Liverpool, Department of Earth and Ocean Sciences, Jane Herdman Laboratories, 4 Brownlow Street, Liverpool, L69 3GP, United Kingdom
AU: * Nippress, S E
EM: nippress@liverpool.ac.uk
AF: University of Liverpool, Department of Earth and Ocean Sciences, Jane Herdman Laboratories, 4 Brownlow Street, Liverpool, L69 3GP, United Kingdom
AU: Rietbrock, A
EM: A.Rietbrock@liverpool.ac.uk
AF: University of Liverpool, Department of Earth and Ocean Sciences, Jane Herdman Laboratories, 4 Brownlow Street, Liverpool, L69 3GP, United Kingdom
AB: The Canary Islands are situated in the North Atlantic Ocean, <200km west of Morocco, Africa. The islands are volcanic ocean islands, associated with the classic hot spot characteristic combination of bathymetric, gravity and geoid anomalies. However, unlike the classic hot spot location of Hawaii, the archipelago is located on a slow moving plate, showing more similarities to the Cape Verde Islands, but unlike both Hawaii and Cape Verde, the Canary Islands are close to the continental shelf. The aims of this work are to provide seismic constraints on the structure beneath the Canary Islands to determine whether this structure indicates a clear age progression across the archipelago as observed at Cape Verde and to determine whether deeper structure may illuminate the source of the hot spot features. To take a transect through the Canary Islands using receiver function analysis, we re-analysed broadband data from the MIDSEA project station (available through IRIS), CDLV on Lanzarote (1999-2001), but apply the multiple- taper spectral correlation estimate for receiver function calculation. We also analysed broadband data from the IRIS Network station of TBT from La Palma (1993-1996). Additionally we also use data from a short period seismic network consisting of 150 short period stations installed for 2 weeks as part of the TOM-TEIDEVS project on the island of Tenerife. Only 1 teleseismic event suitable for receiver function analysis was recorded during this period. Initially an average of all events was to be used for modelling, but significant differences in receiver function shape between different areas of the island, suggested separate stacks for different regions was more appropriate. Initial forward modelling for the average azimuthal stack for CDLV, supports earlier receiver function work that indicates a crust thickened up to ~20km depth, but no evidence of a continental like structure. The average azimuthal stack for TBT shows few details, but when events are grouped by back azimuth and stacked, significant differences in shape are observed. Comparison of the tangential components for different back azimuths, suggests the existence of dipping and/or anisotropic layers. Forward modelling for a stack of data from the caldera in Tenerife, indicates no crustal thickening. This suggests a relationship between crustal thickening and age across the archipelago. Further analysis and application of grid search methods will reveal the structure beneath each of the islands in more detail and indicate whether a thermal or a compositional origin is more appropriate for the islands.
DE: 3037 Oceanic hotspots and intraplate volcanism
DE: 7203 Body waves
DE: 7220 Oceanic crust
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting