The Sedimentary Sequences of the Lesser Antilles Arc South of Guadeloupe FromWide-Angle and Reflection Seismic Data.

Demir, Nur, Kopp, Heidrun , Flueh, Ernst R., Klaeschen, Dirk , Weinzierl, Wolfgang, Hirn, Alfred and Laigle, Mireille and Thales Working Group (2011) The Sedimentary Sequences of the Lesser Antilles Arc South of Guadeloupe FromWide-Angle and Reflection Seismic Data. [Talk] In: EGU General Assembly 2011. , 03.-08.04.2011, Vienna, Austria ; p. 5872 . Geophysical Research Abstracts (13).

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Abstract

The Lesser Antilles Island Arc is a European active subduction zone prone to major earthquakes. Huge sedimentary
input by the South American rivers, namely Amazon and Orinoco, has formed one of the largest accretionary
complexes in the world. In the framework of the THALES project, several coincident wide-angle and multichannel
seismic (MCS) profiles (15.5N and 16.5N) have been collected on the accretionary prism beetween the Barracuda
and Tiburon Ridges in the Lesser Antilles. We present the analysis results of these data in order to construct a
structural model. Preliminary results of 7 different MCS profiles are discussed. The data consist of 1 strike and
6 cross lines. The sedimentary layers imaged on deep-penetrating MCS data were used as a priori information
for the wide angle modelling. A total of 16 OBH/OBS (Ocean Bottom Hydrophone/Seismometer) was deployed
on a 130 km long wide-angle seismic profile. Seismic velocity models were obtained by a forward modelling of
refracted and reflected phases. The final velocity model shows the geometry of the Antilles subduction zone with
a sediment thickness of up to 2.6 km. The shallowest layer has a fill velocity of 1.8-2.2 km/s, whereas an older
more compacted sediment layer in the deeper portion shows velocities ranged from 2.5 to 3.5 km/s with sediment
thickness till 4.3 km. The sedimentary succession marked topographic irregularity and different directional fault
system. These layers overlie oceanic crust having velocities in excess 6 km/s with depth of 14-15 km. From the coincident MCS seismic profiles, we incorporated the well resolved sedimentary portions into our model.

Document Type: Conference or Workshop Item (Talk)
Keywords: Geodynamics
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Date Deposited: 10 Feb 2011 11:53
Last Modified: 06 Jul 2012 15:13
URI: http://oceanrep.geomar.de/id/eprint/11001

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