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Progressive Deformation of the Mexican Fold-Thrust Belt

Elisa Fitz-Diaz
University of Minnesota, Department of Geology and Geophysics Saint Paul, MN, 55108 [email protected]

The Mexican Fold-Thrust Belt (MFTB) is the southern termination of the Rocky Mountain Fold-Thrust Belt (RMFTB). Although b seem to constitute a continuous structure, they differ in width, age and paleogeographical position with respect to the North American continent. In the Vizarrón-Tamazunchale area (central Mexico), a complete cross section of the MFTB is exposed along 150 km. The cretaceous carbonate rocks of this area present lateral variations of facies in different paleogeographical elements, from west to east: El Doctor Platform, Zimapan Basin, Valles SLP Platform and Tampico Misantla Basin. The mechanical differences between platforms and basins resulted in a partitioning of deformation during late Cretaceous shortening, resulting in broad, km-scale, upright folds in the former, and in tight, meter-scale, recumbent folds in the latter.
     This project has two main purposes: 1) To evaluate the effect of platforms in the progressive deformation of basins, and 2) To analyze the role of fluids at different scales during shortening deformation. For that, an integral structural study that includes different scales of observation is underway. Special attention is being paid to the analysis of veins associated with shortening structures, because veins are sensitive structures of instantaneous strain, because they can be used as passive markers of progressive deformation, and because confined veins record the thermal conditions of deformation, which can be deciphered through microthermometry of fluid inclusions or by stable isotopes analysis.

 

AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid