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The Pinacate Volcanic Field of northwest Sonora, Mexico is a predominantly an alkali basaltic volcanic field covering an area of ~1500 km2. The field hosts over 400 scoria cones and 8 maars, as well as a trachyte shield volcano known as both Cerro del Pinacate and Santa Clara Volcano in the southern-centre of the complex. Country rocks are Precambrian schists and gneisses intruded by Mesozoic and lower Cenozoic granitic plutons. Two lava series are occur: the older, basalt-trachyte Santa Clara series and the younger basalt-hawaiite Pinacate series. The Pinacate series flows contain notably glassy, “gem-quality” megacrysts of labradorite with phenocrysts of olivine, augite, magnetite, and rare kaersutite. The Santa Clara series contains labradorite in the lower, less evolved sequences, with feldspars evolving to a more sodic character in upper sequences rimmed by alkali feldspar in trachytes. Geochemical data including whole rock major and trace element and Sr isotopic can be found in Lynch (1981), with a description of the volcanic field found in Gutmann (2007).
GUTMANN, J.T., 2007. Geologic Studies in the Pinacate Volcanic Field. Journal of the Southwest 49:2 pp 189-243. LYNCH, D.J., 1981. Genesis and Geochronology of Alkaline Volcanism in the Pinacate Volcanic Field North-western Sonora, Mexico. Doctoral Thesis, University of Arizona. ZAWACKI, E.E., CLARKE, A.B., ARROWSMITH, J.R., CONSTANZA, B. & LYNCH, D.J., 2019. Tecolote volcano, Pinacate volcanic field (Sonora, Mexico): A case of highly explosive basaltic volcanism and shifting eruptive styles. Journal of Volcanology and Geothermal Research 379 pp 23-44