Investigation of Fault Systems Controlling Breakup and Deposition in the Galicia Rift Margin
Abstract
The Galicia Margin offshore of Spain represents a magma-poor end member of rifting systems. The development of these systems can be understood by imaging the subsurface distribution of crust and upper mantle. The Galicia Margin has been studied extensively with seismic data, and the research cruise R/V Marcus Langseth 1307 collected 3D seismic data along this margin. The dataset includes a 68 by 20 kilometer box in the Deep Galicia Basin and a 110 kilometer x 600 meter 3D swath to the west. Through selective Prestack Depth Migration (PSDM), seismic interpretation, and structural restoration of one of the swaths, one can gain insight into the different fault regimes and depositional history of the margin. PSDM is an important tool to image the subsurface and model the velocities present. Ray based tomography is used to create a migration velocity model that will allow depth migration to faithfully focus the seismic data and send reflection events to their correct location in space. We chose to process Western Extension 1 (WE1), which partially overlaps the 3D box and extends it to the west. This line captures the transition from a crustal necking region to hyperextended crust to exhumed mantle. The eastern 150 kilometers of the line was processed using a 3D Kirchoff algorithm. Its velocity model utilizes reflection tomography in the sediments, and we used forward modeling to minimize residual move out on strong events in the basement. The western 20 kilometer long segment was previously undiscovered due to a lack of geometric control while shots were being recorded. These data were processed using a 2D Kirchoff algorithm using the vessel's navigation systems to estimate source and receiver locations. In this study we found a velocity inversion in the sediment, evidence suggesting a large deposition of synrift sediment in the crustal blocks, and the locations of continental crust and mantle.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.T41E3003A
- Keywords:
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- 8109 Continental tectonics: extensional;
- TECTONOPHYSICSDE: 8120 Dynamics of lithosphere and mantle: general;
- TECTONOPHYSICSDE: 8169 Sedimentary basin processes;
- TECTONOPHYSICSDE: 8178 Tectonics and magmatism;
- TECTONOPHYSICS