Using Ground Penetrating Radar and attribute analysis for identifying depositional units in a fluvial-aeolian interaction environment: The Guandacol Valley, northwest Argentina

ZABALA MEDINA, PETER; LIMARINO, CARLOS; BONOMO, NÉSTOR; SALVÓ BERNÁRDEZ, SALOMÉ; OSELLA, ANA

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2020 vol. 98 p. 102 - 140

0895-9811

This paper deals with the application of the Ground Penetrating Radar (GPR) method and the analysis of attributesof the GPR data to characterize and interpret a fluvial-aeolian interaction field located in the GuandacolValley, northwest Argentina. Several profiles over dunes, interdunes, aeolian mesoforms, and fluvial channelshave been acquired. Each data section is analyzed by using standard images of the amplitude of the electric field,as well as representations of different attributes of the reflections such as contrast, dip, curvature, parallelism,and RMS frequency. The analysis of attributes improves the interpretation of the subsurface, by quantifying andmaking evident properties of the reflection patterns that characterize the sedimentary units. The informationobtained using the GPR profiles allows defining seven radar packages, which are useful for reconstructing theinternal structure of the fluvial-aeolian succession. Packages 1, 2 and 3 illustrate the stratification of differenttypes of low-sinuosity and high-sinuosity aeolian dunes, as well as aeolian mesoforms. Package 4 corresponds tohorizontal or low-angle inclined reflectors obtained in both sandy interdunes and upper parts of several aeoliandunes. A muddy bed that covers most of the area (package 5) probably indicates a period of climate ameliorationlinked to a high level of the water table. The fluvial component of the fluvial-aeolian succession exhibits twodifferent packages; package 6 represents the infill of partially incised fluvial channels with frequent incisions(concave-up bounding surfaces) and bars (convex-up surfaces). Package 7 is composed of the stacking of parallelto subparallel horizontal reflectors, without concave-up surfaces that indicate deep channels. Finally, we proposea conceptual model that relates the principal radar packages with the temporal evolution of the fluvial-aeolianinteraction field of Guandacol Valley.