Volcaniclastic aeolian dunes: terrestrial examples and application to martian sands

On Earth, most aeolian dunes are quartz rich; others are composed of evaporites, carbonates, or clay/silt aggregates. Dunes made of wind-reworked volcaniclastic sediment comprise a less-commonly recognized fifth dune composition. Terrestrial volcaniclastic aeolian dunes are found in (1) arid to semi-arid volcanic regions and (2) coastal areas on volcanic islands. Their sediments can be formed by explosive volcanism or by erosion of lava flows and other lithified volcanic material. Commonly, these sediments have been transported by volcanic and/or fluvial processes before being reworked by wind. Their compositions range from malic to sialic, depending on local volcanic sources. Volcaniclastic dunes, especially those of basaltic composition, may be the best compositional analog for aeolian dunes on Mars. Martian dunes are typically dark-hued and their sands may be derived from erosion of volcanic materials.