TOWARD AN IMPROVED CHARACTERIZATION OF DUNE BED GEOMETRY IN RADARGRAMS: IMPLICATIONS FOR AEOLIAN SEDIMENTOLOGY AND BIOGEOMORPHOLOGY

A new RAID (Rapid Automatic Identification of Dunes) computer algorithm has been developed that facilitates detection and quantification of sedimentological and biogeomorphic features in ground-penetrating radar B-scans (2D radargrams). Using a post-processed dataset of 500 MHz records from barchan and parabolic dunes of the White Sands National Monument, New Mexico, a rapid and effective computation of aeolian bed thickness, length, morphology (sigmoidal/tangential oblique), and continuity, as well as bifurcation (toplap), and truncation that can be related to superposition and reactivation surfaces. An analysis of bounding surfaces and related discontinuities offers means of assessing the complexity of aeolian bedding, as well as addresses features related to incipient lithification, phytoturbation, pediturbation, and burrowing activities by semi-fossorial organisms. The algorithm identifies local amplitude maxima along each A-scan and improves upon the time and accuracy of a recently established internal complexity thresholds for aeolian end members across the dunefield. This approach has the potential of analyzing large datasets of modern and ancient dunefields, with implications to the dynamics, sedimentology, biogeomorpology, and reservoir characterization.