CORRELATION OF DUNE GEOMORPHOLOGY WITH GRAIN SIZE AND DISTRIBUTION, WHITE SANDS, NEW MEXICO

Dune fields and eolian sands are a major feature of the terrestrial landscape; grain size is a readily quantifiable characteristic of sandstone deposits, and bears important implications for both geologic study and engineering or economic analysis. Unfortunately, the correlations between the ephemeral processes of the eolian landscape and the resultant depositional characteristics of a genetic sedimentary rock remain poorly understood. The homogeneous material, relatively simple flow regime, and high local variability of grain size make the White Sands dune field (New Mexico, USA) an ideal site for study of these relationships during active deposition.

Surface samples were collected with corresponding GPS location data across a 3 x 0.5 km swath oriented SW-NE across barchan, transverse/barchanoid, and parabolic dunes and their corresponding interdunes. Areal density of collection was varied to allow comparison across multiple scales of activity. Grain size analysis was performed via laser diffraction. Preliminary analysis indicates in-field sources of coarser sediment derived from poorly or non-vegetated erosional and evaporite interdunes. From these areas, grain size fines both up the stoss slopes of adjacent dunes and in the local downwind direction.