Field-based 3D Modelling of Finite Deformation of the Alpine Corsica Blueschists

@inproceedings{GueydanRM2008,
 abstract = { The processes responsible for exhumation of High-Pressure Low Temperature metamorphic rocks remains a matter of long debate with different hypotheses such as channel-flow, erosion or roll-back. The 3D understanding of the finite deformation of HP-LT metamorphic units could thus provide some critical constrain to discuss the applicability of the various exhumation processes. For that purpose, the Alpine Corsica is ideal because it gathers in the same area continental and oceanic units with different stiffness and thus different finite strain pattern. A new structural map at the scale of the Cap Corse is used to constrain in gOcad the positions of interfaces between different lithologies. 3D geomodelling packages are currently not well adapted for the construction of 3D structural models from spatially limited data such as field data, due to a lack of information in depth. Therefore, specific methodologies are developed for this task within the gOcad geomodeller. Data are: the DEM from SRTM database (80m resolution), geological maps, beddings of thrusts and interpreted crosssections. A three-stage approach is used. (1) data are integrated in 3D and their consistency is checked. (2) geological maps and associated field data (beddings) are drapped onto the DEM, that plays a major role for providing missing information in depth. Interpreted cross-section may also be used. (3) 3D model is used iteratively for building main contact, checking their consistency and correcting accordingly. 3D coherence of folds variations is used to test viability of field-based interpretations and therefore constrain components of deformation. The preliminary results of this field-based 3D modelling of the HP-LT units of Alpine Corsica are 1/ well defined post-peak pressure large scale folding of HP-LT units and 2/ identification of the 3D variation of nappes thickness that can be interpreted as a results of localized thinning during exhumation. },
 author = { Gueydan, Frederic AND Cogné, Nathan AND Le Carlier de Veslud, Christian },
 booktitle = { 28th gOcad Meeting },
 month = { "june" },
 publisher = { ASGA },
 title = { Field-based 3D Modelling of Finite Deformation of the Alpine Corsica Blueschists },
 year = { 2008 }
}