Shallow crustal structure of the junction of the grabens of Chapala, Tepic-Zacoalco and Colima, Mexico

• Published in: Geofísica internacional Vol. 37; no. 4; pp. 263 - 282
• Main Authors: Campos Enriquez, JO, Alatorre Zamora, MA
• Format: Journal Article
• Language: English
• Published: Universidad Nacional Autónoma de México, Instituto de Geofísica 1998
• Subjects: Jalisco Block; limit; shallow crustal structure; Sierra Madre Occidental; Tepic graben; triple junction area; Mexico
• ISSN: 0016-7169

Gravity data are used to infer the shallow crustal structure of the Tepic graben adjacent to the Guadalajara City. This depression does not constitute a symmetric graben with steep master faults but rather a complex transition zone. Blocks detached from the granitic sierras are downfaulted and tilted to the northeast along the front of these sierras. Farther to the north, the granitic basement deepens gradually. However, it steepens at the limit between the Sierra Madre Occidental and the Jalisco Block. Northwest of our study area, the limit is located north of the Plan de Barrancas fault. At the east the limit is located closer to the southward prolongation of the Plan de Barrancas fault. The change in position occur near La Primavera Caldera, Tequila Volcano, and vents of cinder and lava cones are emplaced along NW-SE weakness zones in the batholith. The crust of the Sierra Madre Occidental adjacent to the limit features NE-SW lineaments perpendicular to those of the neighbouring Jalisco Block.