El Álamo district (Baja California, México): A hint of a new Cordilleran orogenic gold belt?
Por:
Lazcano, Javier, Camprubi, Antoni, Gonzalez-Partida, Eduardo, Iriondo, Alexander, Miggins, Daniel P., Ramirez-Salamanca, Gustavo A.
Publicada:
1 ene 2022
Resumen:
The El Álamo is one of the most important historic gold mining districts in the Peninsular Ranges batholith. Gold mineralizations at El Álamo consist in fault-fill laminated quartz veins with small amounts of sulfides and oxides, and lesser amounts of gold. Veins are mainly emplaced along compressional brittle-plastic shear zones within the El Álamo quartz diorite (146.6 ± 1.6 Ma, U–Pb zircon), which is intruded by the San Marcos dike swarm (126.8 ± 1.7 Ma, U–Pb zircon). Several lines of evidence indicate that the dike swarm is older than quartz veins, and the formation of the later is related to the Peninsular Ranges orogeny (~110-98 Ma). Gold bearing quartz veins formed during regional prograde metamorphism (greenschist facies), and the veins subsequently underwent plastic deformation, dynamic recrystallization and metamorphism. Gold remobilization and concentration seems to have been largely enhanced by metamorphism, probably accounting for very high grade, albeit sporadic, bonanza ores, typical of the district. 40Ar/39Ar dating of hydrothermal white micas from the auriferous veins yielded ages of 97.86 ± 0.17 Ma at the Ulises mine and 97.46 ± 0.17 Ma at the La Americana mine. These ages are interpreted as the minimum age of the regional metamorphism in the area. Based on their primary characteristics, the gold deposits from El Álamo district can be ascribed to the orogenic gold type. These deposits are similar to other known deposits in the same orogenic context (e.g., Julian district; southern California), and they probably conform a new Cordilleran orogenic gold belt that could extend over much of the exhumed axis of the Peninsular Ranges batholith. © 2022 Elsevier Ltd
Filiaciones:
Lazcano, Javier:
Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, Querétaro, 76230, Mexico
Camprubi, Antoni:
Instituto de Geología, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán, CDMX, 04510, Mexico
Gonzalez-Partida, Eduardo:
Centro de Geociencias, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, Querétaro, 76230, Mexico
Iriondo, Alexander:
Centro de Geociencias, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, Querétaro, 76230, Mexico
Department of Geosciences, University of Arizona, 1040 E 4th St, Tucson, AZ 85721, United States
Miggins, Daniel P.:
College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Ocean Administration Building, 104, 101 SW 26th St, Corvallis, OR 97331, United States
Ramirez-Salamanca, Gustavo A.:
Posgrado en Ciencias de la Tierra, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, Querétaro, 76230, Mexico
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