Geología Estructural Y Tectónica

GEOS, GEOS Vol. 25, No. 1, Noviembre, 2005

SESIÓN

GEOLOGÍA ESTRUCTURAL Y TECTÓNICA

MIÉRCOLES 2 Y JUEVES 3 SALÓN VALLARTA 3

GEOLOGIA ESTRUCTURAL Y TECTONICA

GEOS, GEOS Vol. 25, No. 1, Noviembre, 2005

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GEOS, GEOS Vol. 25, No. 1, Noviembre, 2005

GEOLOGIA ESTRUCTRUCTURAL Y TECTONICA

G E T- 1 TERRAIN MODELING USING THE SHUTTLE RADAR TOPOGRAPHY MISSION (SRTM) VA DAT E L EVATION DATA FOR MEXICO Masuch Oesterreich Dirk
Geologo d m a s u c h o @ p r o d i g y. n e t . m x Digital Elevation Models are a useful tool in the interpretation of geological structures. Depending on the resolution of the model they can be applied from continental to local scales. The elevation model developed for Mexico presented here is based on the NASA Shuttle R adar Topography MissionElevation (SRTM) data collected by the Endeavour spacecraft in 2000. For this model the elevation data in DTED Level 1 format were used as distributed by the US Geological Sur vey. These data have a cell spacing of three arcseconds (aprox. 87 m) and are referenced to the WGS84 horizontal datum and to the EGM96 geoid. The DTED data are known in the GIS community as the «finished» SRTM data. Comparedto the research level «unfinished» data in HGT format they underwent a number of improvements: Water bodies and lakes of more than 600 meters length were depicted, flattened out and set to a constant height. The ocean elevation was set to 0 meters. Islands are represented in the data whenever their axis is longer than 300 meters or their relief is greater than 15 meters. Spikes and wells in thedata were detected and voided out. Small voids of less than 16 cells were filled by interpolation. However, in the original USGS data set large voids were left in the data resulting in nodata areas of occasionally significant extension. Within the territory of Mexico voids are found in those parts of the country that exhibit significant changes of relief over short distances, like in the steepcanyons of the Sierra Madre Occidental. The largest nodata area lies in the south of Chihuahua state close to Sinaloa and Sonora states and covers an area of approximately 3000 km2. The DEM presented here was enhanced in several ways. The DTED data were merged into one seamless DEM for the entire Republic of Mexico. Voids and nodata areas were identified and filled. Due to the size of the nodata areain the state of Chihuahua the voids were filled with existing elevation data rather than by interpolation. For this purpose the GTOPO30 DEM was used which reduces the resolution of the model within the affected areas to 1 km2. The DEM was resampled and projected from arcseconds to decimal degrees. This process established compatibility between the DEM and the vector data available for Mexico aspublished by the INEGI as well as the data of the Digital Chart of the World.

The result is a seamless 90 meters resolution DEM for the entire territory of Mexico that has exceptional detail in the coastal areas of the country while preserving a high level of detail in the mountainous regions and in the Transmexican Volcanic Belt. Applications of the model are manifold and include hydrologicalbasin and surface water management, geological risk analysis, slope stability analysis, structural interpretation, and geohazard prediction and mitigation. The DEM is one of the most detailed elevation models available for Mexico while covering the whole country in one seamless and accurately projected model.

G E T- 2 PRE-VARISC METAMORPHIC CONTRASTING PRE- VARISC AN METAMORPHIC STYLES IN THEUPPERMOST UNITS OF THE ALLOCHTHONOUS COMPLEXES OF GALICIA (NW IBERIAN MASSIF): IMPLIC ATIONS FOR THE DEVELOPMENT OF AN ACCRETIONARY COMPLEX Castiñeiras García Pedro (Dpt. Geological Sciences, University of Colorado at Boulder, USA), Gómez Barreiro Juan (Dpto. de Geología, Facultad de Ciencias, Universidad de Salamanca, España), González Cuadra Pablo (Dpto. de Ingeniería Minera. Universidad de León,...