Petrographic and geochemical analyses of dune sands from southeastern Mexico, Oaxaca, Mexico

Abstract

Dune sands in southeastern Mexico are compositionally and geomorphologically controlled by fluvial input, eastward longshore currents, and the intense winds traveling through the Isthmus of Tehuantepec. Tehuano winds are mainly responsible for the remarkable dune sand entrapment circumscribed to the exposure of volcanosedimentary outcrops. Compositionally, the dunes are potentially influenced by granite denudation, volcano-sedimentary rocks, metamorphic units, and Quaternary sediments besides alluvium. Mono-to polycrystalline subangular to angular quartz, K-feldspar, and schists suggest that granitic-metamorphic rocks control the river and dune sands composition. Subordinate fractions of mica, Fe-Ti oxide minerals, and reduced amphibole (actinolite) indicate metamorphic-volcano sedimentary-granite as the potential parent rock of sand sources. The dune sands compositional framework shows slight flat-type rare earth elements (REE) trends with a low light rare earth elements (LREE)/heavy rare earth elements (HREE) ratio (e.g., 6.13 ± 6.00), suggesting a significant control of granite rocks. Geochemical signals, CIA and CIW chemical indices support moderate weathering. The petrographic and geochemical analyses indicate little dune sand recycling by aeolian transport despite strong wind systems along the SE coast of Mexico. This provenance study evidences the exhumation of granite, metamorphic, and volcano-sedimentary materials in the Oaxaca dune sands, confined by the regional geomorphology.

Provenance of sediments from Barra del Tordo and Tesoro beaches, Tamaulipas State, northwestern Gulf of Mexico

“…The geochemistry of beach sediments in the Gulf of Mexico have been studied by various authors (Rosales-Hoz et al 2015;Machain-Castillo et al 2019;Ayala-Pérez et al 2021;Kasper-Zubillaga et al 2021), whereas the U-Pb ages of detrital zircons from the Gulf of Mexico coastal sediments have not been studied extensively. Nevertheless, U-Pb ages of zircon grains in volcanic rocks from various terranes in Mexico such as Cuicateco, Oaxacan Complex, Xolapa Complex, Mesa Central Province, and Eastern Alkaline Province were widely studied (Solari et al 2004;Rubio-Cisneros and Lawton 2011;Lawton and Molina-Garza 2014;Juárez-Arriaga et al 2019;Sieck et al 2019;Barboza-Gudiño et al 2020;Torres-Sánchez et al 2020;Verma et al 2021).…”