HR: 0800h
AN: T41A-0350    [Abstracts]
TI: Young Conjugate Margins Laboratory in the Gulf of Aden : the YOCMAL project
AU: * LEROY, S
EM: sylvie.leroy@lgs.jussieu.fr
AF: CNRS UPMC, 4 place Jussieu, Paris Cedex 05, 75252, France
AU: LUCAZEAU, F
EM: lucazeau@ipgp.jussieu.fr
AF: IPGP, 4 place Jussieu, Paris, 75252, France
AU: RAZIN, P
EM: razin@egid.u-bordeaux.fr
AF: Bordeaux III Univ., 1 allee Daguin, Pessac, 33607, France
AU: MANATSCHAL, G
EM: manatschal@illite.u-strasbg.fr
AF: EOST, 5 rue Rene Descartes, Strasbourg, 67084, France
AU: team, Y
EM: yocmal@aden.com
AB: A comprehensive multi-disciplinary study of the eastern part of the Gulf of Aden has been undertaken recently in the framework of the French margins program (Encens project), with the long-term objective to integrate in a consistent model of evolution field observations where the margin crops out, results of marine geophysical survey where the margins are submerged, seismological observations of deep interior structure and geodetic measurements. First results show the potentiality of such an approach in this area to understand the relationships between the dynamics of rifting and spreading, the observed structures and the vertical motions of a margin in its early stages. Among the main results, we evidence the structural and sedimentologic characteristics of the continental and oceanic domain of the margin, especially their segmentation, related to the opening obliquity, and their consequences on the oceanic spreading, the importance of the structural inheritance at both lithospheric and crustal scale. We also describe the presence of a ocean-continent transition zone with high heat flow values, of a deep thermal anomaly (170 km) and of a sub-active volcano in the deep margin, that relaunch debate on the importance of the volcanism in the margins formation. The results also emphasize that both the area of investigation and the methods should be extended to be able to describe and understand the variability and the evolution in space and time of the studied structures, notably related to the Afar hotspot. This project intends therefore to study the Gulf of Aden as a natural laboratory for the study of rifting and oceanic spreading onset processes. The extended further ongoing investigations onland in the eastern area (Oman) and its conjugate margins in the South (Socotra island) and in the volcanic margin in the West (Yemen) allow to reach the objectives concerning: - The deep structure and thermal regime (seismic tomography, OBS, heat-flow). - The crustal structure (tectonics-sedimentation relationships, MCS, Ocean Bottom Seismometer, receiver functions on land, gravity and magnetic anomalies, dredging on the ocean-continent transition, basalts geochemistry). - The vertical motions throughout the Cainozoic (topography-bathymetry analysis, sedimentology and stratigraphy field work, apatite fission tracks and U/Th/He thermochronology) and more recent deformation (concentrations of cosmogenic elements) - The present-day opening (GPS network monitoring and extension of the network) - The thermo-mechanical modelling (numerical and analogue models). The overall goal of this project is to build 3D images of the deep (mantle), intermediate (crust), and superficial (sediments) structures of the Gulf of Aden basin from its rifting to its present-day oceanic spreading in order to understand the mechanisms of continental margins formation.
DE: 8105 Continental margins: divergent (1212, 8124)
SC: Tectonophysics [T]
MN: 2007 Fall Meeting