Artículo

Geochemistry and mineralogy of the Eocene-Ogligocene volcanic sequence, Southern Sierra Madre Occidental, Juchipila, Zacatecas, Mexico.

Webber, K. L.; Fernández, L. A.; Simmons, Wm. B.

Instituto de Geofísica, UNAM, publicado en Geofísica Internacional, y cosechado de Revistas UNAM

Licencia de uso

Procedencia del contenido

Entidad o dependencia
Instituto de Geofísica, UNAM
Revista
Repositorio
Contacto
Revistas UNAM. Dirección General de Publicaciones y Fomento Editorial, UNAM en revistas@unam.mx

Cita

Webber, K. L., et al. (1994). Geochemistry and mineralogy of the Eocene-Ogligocene volcanic sequence, Southern Sierra Madre Occidental, Juchipila, Zacatecas, Mexico. Geofísica Internacional; Vol. 33 No. 1, 1994. Recuperado de https://repositorio.unam.mx/contenidos/42270

Descripción del recurso

Autor(es)
Webber, K. L.; Fernández, L. A.; Simmons, Wm. B.
Tipo
Artículo de Investigación
Área del conocimiento
Físico Matemáticas y Ciencias de la Tierra
Título
Geochemistry and mineralogy of the Eocene-Ogligocene volcanic sequence, Southern Sierra Madre Occidental, Juchipila, Zacatecas, Mexico.
Fecha
2012-06-12
Resumen
The Sierra Madre Occidental (SMO) volcanic province of western Mexico is a remnant of a broad continental-margin orogenic belt formed as a result of mid-Tertiary subduction of the Farallon plate beneath Mexico. The most voluminous rocs exposed in the SMO are rhyolitic ash-flow tuffs (AFT) erupted throughout most of the providence from 36 to 27 Ma. Two other magmatic episodes recorded in the SMO include an Eocene event (53-40 Ma) characterized by mafic-intermediate composition lava flows, and a post-ignimbrite event (29-20 Ma) characterized by the eruption of extension-related basaltic-andesites. This paper presents new data for an area in the southem SMO wich has evidence for both Eocene and Oligocene volcanism. Te stratigraphic sequence established for the area near Juchipila, Zacatecas, consists of Eocene basaltic andesite to andesite lava flows wich are uncomfortably overlain by Oligocene basalt to basaltic lava flows and/or Oligocene rhyolitic ash-flow tuffs. An upper sequence of basalt to andesite lava flows caps the section. The high-K calc-alkaline Oligocene sequence is composed predominantly of rhyolitic AFT (~25 Ma) wich are younger than most other reported SMO occurrences. This suggest a younging to the south of SMO volcanism. Although Juchipila AFT are phenocryst poor, one widespread AFT unit is characterized by alkali feldspar with unusually Ba-rich cores (up to 14% celsian component). This is the first reported occurrence for this composition feldspar in the SMO.
Tema
Sierra Madre Occidental; tobas de flujos de cenizas; riolita; andesita; feldspato de bario; Sierra Madre Occidental; ash-flow tuff; rhyolite; andesite; barium feldspar
Idioma
spa
ISSN
0016-7169

Enlaces