CONSTRAINING A CHRONOSEQUENCE OF FLUVIAL TERRACES USING SOIL PROFILE ANALYSIS AND GIS MAPPING IN THE SANTA ROSALIA BASIN, BCS, MéXICO.
During the initial phase of study, fluvial terraces were mapped using GIS in the field while soil horizons of terraces lining each arroyo were observed, described, and sampled. Soil horizon compositions will be determined by grain size analysis, XRD, and thin section microscopy. Soil development indexes will be assigned to soil profiles characterized in the field following the method outlined by Harden(1982) on the basis of various soil properties. GIS analysis of relative soil development on terraces of varying elevations and locations will allow interpretation of regional tectonics during terrace formation.
We expect to see varying levels of fluvial terrace soil development in Arroyos Santa Agueda and Boleo despite corresponding elevations. Relative rates of terrace uplift compared with terrace development will allow interpretation of differences in tectonic activity in the two catchments which limit the Santa Rosalia basin to the south and north, respectively. The constraints provided by this analysis will generate new insights into development of the Santa Rosalia basin. When combined with absolute geochronology, this will be the first fluvial terrace chronosequence developed for central Baja California, a powerful tool for regional paleoclimate and geochronology studies in the future.
Reference: Harden, J., 1982, Geoderma, vol. 28, pg. 1-28.