HR: 1340h
AN: T23B-1425    [Abstracts]
TI: Ocean crust deformation at the North America-South America plate boundary: Results of the 2007 ANTIPLAC marine survey
AU: Patriat, M
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Benard, F
AF: IFP, 1-4, av. Bois-Préau, Rueil-Malmaison, 92852, France
AU: * Deville, E
EM: eric.deville@ifp.fr
AF: IFP, 1-4, av. Bois-Préau, Rueil-Malmaison, 92852, France
AU: Le Drezen, E
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Loubrieu, B
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Maltese, L
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Roest, W
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Thereau, E
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Umber, M
AF: IFREMER, DRO-GM, BP 70, Plouzané, 29280, France
AU: Vially, R
AF: IFP, 1-4, av. Bois-Préau, Rueil-Malmaison, 92852, France
AB: East of the Lesser Antilles active margin, the area of the Barracuda and Tiburon ridges is resulting from of a multidirectional and polyphase tectonic history at the diffuse plate boundary between the North and South American plates. These WNW-ESE trending ridges control the sediment distribution and they are bounded by sedimentary trenches, both ridges and trenches trending parallel to the Mid-Atlantic oceanic fracture zones. A marine survey (called ANTIPLAC) conducted in the beginning of the year (January 2007) has provide new evidences (multibeam and seismic acquisition) of the deformation processes which occurred at this plate boundary. On the seismic lines, a major angular unconformity can be recognized in the whole area of the survey. Interpreting the acquired seismic grid, the lower part of the stratigraphic series can be easily tied to the DSDP/ODP holes of legs 78A, 110, 156, 171A, especially with wells 543 and 672. Thus a Maastrichtian-Pliocene age can be attributed to the geological formations located below the regional unconformity. The very recent geological formations located above the unconformity (attributed to the Late Pliocene-Pleistocene) tend to fill the main depressions of the area and show very heterogeneous thickness. These recent deposits can be more than 3 s(TWT) thick in the Barracuda trough (north of Barracuda ridge). Globally they show clear onlapping characters above the older levels, but in some places these levels show spectacularly evidences of syntectonic deposition. This is notably the case of a narrow WNW-ESE trending fold and fault system trending along the axis of the Barracuda trough. South of Barracuda ridge the recent deposits show also locally spectacular fan geometries characterizing deposition during significant tilting. Also, between Barracuda and Tiburon ridges several fracture zones show evidences of very recent (and probably active) reactivation. This recent deformation is also characterized by recent basin inversion structures. Finally and more generally, the data acquired during the ANTIPLAC survey demonstrate that high deformation occurred at the boundary between the North and South American plates during much more recent times than previously thought, and that notably spectacular compressional structures resulting from the convergence between the two american plates developed recently during Late Pliocene-Quaternary times. The subduction of this structural pattern and its partial incorporation within the Barbados tectonic wedge has widely influenced the deformation processes within the accretionary prism and has also induced segmentation within the overriding Caribbean plate.
DE: 0930 Oceanic structures
DE: 0935 Seismic methods (3025, 7294)
DE: 3039 Oceanic transform and fracture zone processes
DE: 3040 Plate tectonics (8150, 8155, 8157, 8158)
DE: 3045 Seafloor morphology, geology, and geophysics
SC: Tectonophysics [T]
MN: 2007 Fall Meeting