AEOLIAN ABRASION AND DUST EMISSION POTENTIAL OF BASALTIC AND OTHER VOLCANICALLY DERIVED SANDS: AN ANALOG FOR DUST PRODUCTION ON MARS

Aeolian abrasion and wind erosion of volcanically derived sediments on Mars have been identified as major sources of dust. Previous studies that attempted to simulate aeolian abrasion using sediment analogs agree that abrasion is an important process, but dust concentrations have not been measured. This study used the Potable In Situ Wind Erosion Laboratory (PI-SWERL) to measure the dust emission potential of volcanically derived sands collected from the Pacific Northwest, Utah, Hawaii, and Iceland from aeolian dunes, beaches, and fluvial deposits. Samples ranged from very fine to very coarse subrounded to very angular sand and wet sieved to remove dust-sized particles. The sands were subjected to shear velocities in the PI-SWERL of 0.4 to 0.9 m/s, velocities that are within the range of thresholds of aeolian transport on Mars. Concentrations of dust (mg/m³) generated during tests from 1 to 30 min in duration were measured as particulate matter <10 μm (PM₁₀) and total suspended particulate (TSP) and converted to fluxes in mg/m²/s. Dust fluxes were compared by sand composition: 1) basalt, with grains composed on groundmass and occasional phenocrysts of feldspars, with some grains having vesicles filled with iron oxides or calcite; 2) volcanic glass; 3) olivine mixed with basalt, and 4) other volcaniclastic sediment composed of tuff, andesitic grains, or pumice. The largest mean dust fluxes (PM₁₀-TSP: 0.8-1.8 mg/m²/s) were measured from the “other” category, with the fine-grained, fragmental nature of the sand likely facilitating abrasion during saltation transport. Basalt sands produced 0.4-0.8 mg/m²/s, likely related to the ease at which basalt groundmass can be abraded. Glass produced 0.3-0.5 mg/m²/s, and olivine produced 0.2-0.4 mg/m²/s. Size and shape analysis of angular volcanic glass before and after PI-SWERL testing revealed that the sand became finer and rounder following 30 min of saltation. Compared to other abrasion studies, basalt sands tend to produce more dust compared to >90% quartz sand (0.3-0.6 mg/m²/s), but less than gypsum sands (4.0-6.7 mg/m²/s). The moderate to high dust fluxes from volcanically derived sands suggests aeolian abrasion is an effective mechanism for dust production on Earth and Mars.