Microtextures on quartz and zircon grain surfaces in the Barra del Tordo and Tesoro beaches, northwestern Gulf of Mexico

Abstract

Surface features of quartz and zircon grains in the Barra del Tordo (PBT) and Tesoro (PT) beaches, NW Gulf of Mexico (GoM), were analyzed. The microtextures in the PBT and PT beaches were classified into mechanical, chemical, and mechanical/chemical origin. The quartz grains from the two beach areas were subrounded to rounded in shape. Rounded zircon grains in PT suggest that the sediments were derived by wind, long transport distance, and long residence time relative to PBT. Rounded quartz grains with the combination of bulbous and broken edges indicated a recycled provenance. Mechanical features such as V-shaped marks, impact scars, conchoidal fractures, and straight-curved grooves indicated a fluvial environment. Chemical features such as solution pits, crystal overgrowth, and adhering particles in quartz and zircon grains indicated a diagenetic environment and silica re-precipitation in a coastal environment. The association of mechanical (bulbous edge) and chemical (silica overgrowth, small and large solution pits) features in a single grain suggested a dual environment, that is, the combination of littoral and coastal environments. The sediments were also partly supplied by the coastal dunes located along the GoM coastal region and were redistributed by wave energy and littoral currents. Euhedral, subhedral, and unetched zircon grains in PBT and PT were mixed with rounded and etched grains, indicating a diverse provenance from crystalline rocks. In general, the microtextures identified on zircon and quartz grains reveal that sediments are influenced by wind, fluvial, and subaqueous marine environment and derived by nearby and distal sources.