Resumo

KASPER-ZUBILLAGA, Juan José; LINARES LOPEZ, Carlos  e  ESPINO DE LA FUENTE MUNOZ, Carmen Adela. Provenance of opaque minerals in coastal sands, western Gulf of Mexico, Mexico. Bol. Soc. Geol. Mex [online]. 2016, vol.68, n.2, pp.323-338. ISSN 1405-3322.

This paper contributes to the study of the provenance of opaque minerals (OM), i.e ., ilmenite, titanomagnetite, and magnetite in beach and dune sands from the western coast of the Gulf of Mexico. Grain sizes in the sands are controlled by a wide coastal plain that also influences their distribution. The quartzose nature of the beach and dune sands from the western coast of the Gulf of Mexico is derived from Upper Cretaceous and Tertiary shales and sandstones exposed along the coast from the Miramar to the Tepehuajes beach sites and from denudation cycles from the Sierra de Tamaulipas which is composed of intrusive rocks. This is supported by the presence of sandstones, chert, monocrystalline quartz with straight extinction, K-feldspars, amphiboles, and pyroxenes. The OM subordinate fractions in the beach and dune sands studied show that ilmenite is primarily derived from pre-existing eroded mafic sources, i.e. , alkali basalts originating from the Aldama and Sierra de Maratínez volcanic field sites that are exposed close to the Miramar beach. The primary sources of titanomagnetite and magnetite subordinate fractions come from subalkaline basalts from the Aldama rocks low in K-feldspar with an increase in Ca-plagioclase and also from granites from the Sierra de Tamaulipas, respectively. The OM grains like ilmenite, titanomagnetite, and magnetite are subrounded, and from rounded to very rounded, suggesting longshore transport, breaking wave influence, and wind deflation effect from the source rock to the beach site.

Palavras-chave : opaque minerals (OM); ilmenite; titanomagnetite; magnetite; beach; dune sands; roundness; Gulf of Mexico; Mexico.

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