HR: 0800h
AN: T41A-0366    [Abstracts]
TI: Insights on the Deep Structure of the Iberia Abyssal Plain and Galicia Bank Southern Edge From new MCS and Wide Angle Data
AU: * Lourenco, N
EM: jlourenco@emepc.gov.pt
AF: EMEPC, R. Costa Pinto, 165, Paco de Arcos, 2770-047, Portugal
AU: Afilhado, A
EM: afilhado@dec.isel.ipl.pt
AF: ISEL, R. Conselheiro Emídio Navarro, Nš1, Lisbon, 1950-062, Portugal
AU: Pimentel, F
EM: fmmpimentel@emepc.gov.pt
AF: EMEPC, R. Costa Pinto, 165, Paco de Arcos, 2770-047, Portugal
AU: Matias, L
EM: lmmatias@fc.ul.pt
AF: IDL, Universidade de Lisboa Edificio C8, Campo Grande, Lisbon, 1749-016, Portugal
AU: Abreu, M
EM: mapabreu@emepc.gov.pt
AF: EMEPC, R. Costa Pinto, 165, Paco de Arcos, 2770-047, Portugal
AU: Miranda, M
EM: jmmiranda@fc.ul.pt
AF: IDL, Universidade de Lisboa Edificio C8, Campo Grande, Lisbon, 1749-016, Portugal
AB: In the scope of the Portuguese Continental Shelf Extension Program, 1600 km of 2D MCS reflection lines were acquired over the Iberia Abyssal Plain and the southern edge of the Galicia Bank. The survey ties in with other academic and industry surveys. It comprised four E-W lines, crossing from continental to oceanic crust along the Zone of Exhumed Continental Mantle, and two N-S lines crossing the Iberia abyssal plain from the Galicia Bank to the Tore seamount and the Tagus Abyssal plain. Additionally nine OBSs were deployed along the MCS IB02 profile (roughly at 41°N). The MCS acquisition layout consisted in a streamer 8 km long and an array of bolt long- life air guns (5720 cu.in.). In order to record deep reflections the record length was set to 18 s. The E-W lines were Kirchoff pre-stack time (PSTM) and depth migrated (PSDM). Velocity model for the depth migration was obtained on the sedimentary cover by using a grid based tomography algorithm from Paradigm's Geodepth software, and constrained, from the basement to deeper sections, using IB02 wide angle results and other published refraction studies on the area. Results show a clear improvement of the PSDM lines with respect to the original time migrated lines, especially in the deeper sections. A good agreement is verified between the wide-angle IB02 velocity model and the coincident depth migrated MCS line. The basement topography is highly variable across the studied lines and suggests that the tectonic segmentation pattern of the margin is complex in this sector. Mid to High amplitude intra-basement reflectors are often observed: i) forming wedges internally defined by sets of sub-parallel reflectors, sometimes disrupted by high angle faults (pre-rift sequences?); ii) Consisting on several low angle intra-basement reflectors, interpretable as detachments faults, dipping both westward and eastward and reaching, in some cases, at least a depth of 20 km. We discuss the implications of our interpretations, from these enhanced PSDM images, to the existing tectonic models for this segment of the West Iberian Margin.
DE: 8178 Tectonics and magmatism
SC: Tectonophysics [T]
MN: 2007 Fall Meeting