Obtention of reproducible structural lineaments from a DEM (SRTM3): Development and applications for the study of an area in the Septentrional Patagonian Andes.

GALLEGOS, E.; MARTÍNEZ DOPICO, C.I.; BERBEGLIA, Y.

Bahía Blanca, Pcia. de Buenos Aires

Otro; XXIII Reunión Científica Asociación de geofísicos y geodestas; 2006

Asociación de Geofísicos y Geodestas de la República Argentina

This paper explores the usefulness of mapping lineaments with shaded relief maps produced by satellite image analysis software from Digital Elevation Models (DEM) of three seconds spatial resolution. The area of study is located between 39ºS and 39º30´S and between 71ºW and 71º30?W and three shaded relief maps were use with incident light at 45º from the horizontal and azimuths of 120º, 240º and 360º. Three operators mapped lineaments separately in the different images obtaining a result of nine independent maps. Reproducible lineaments were considered only those mapped in at least two shaded relief maps by at least two operators or by three operators in at least one image, in the end 23 lineaments were obtained. The tendencies observed were 55º, 106º, 140º and 153º. These lineaments were compared with lineaments mapped in a GeoCoverTM Landsat Enhanced Thematic Mapper Imagery ortorrectified compressed mosaic, in the geologic map 1:200.000 (SEGEMAR) and in topographic maps 1: 50.000 (IGM). Some lineaments that were clearly identified with the DEM were not observed in the geological and topographic maps or in the Landsat imagery. The authors consider there are certain advantages in applying digital elevation models in the mapping of regional lineaments: 1) the users can control the incident angle and its azimuth; 2) The working scale can be change as needed; 3) in contrast to aerial photography, the satellite data have no deformation and it doesn´t show any kind influences with anthropologic features or interference in the interpretation due to vegetation. Another advantage of the DEM (SRTM3 V2) and the GeoCover? image used in this procedure is that the data is for free access and almost cover all the Earth. The correlation between the presented technique and geology, faults and fractures suggest that DEM can be a very important component in the geological mapping. The obtained lineaments must be checked with the structural information obtained in the field to be validated.