A 3D model of crustal magnetization at the Pinacate Volcanic Field, NW Sonora, Mexico
Por:
García-Abdeslem J., Calmus T.
Publicada:
15 ago 2015
Resumen:
The Pinacate Volcanic Field (PVF) is located near the western border of the southern Basin and Range province, in the State of Sonora NW Mexico, and within the Gulf of California Extensional Province. This volcanic field contains the shield volcano Santa Clara, which mainly consists of basaltic to trachytic volcanic rocks, and reaches an altitude of ~ 1200 m. The PVF disrupts a series of discontinuous ranges of low topographic relief aligned in a NW direction, which consist mainly of Proterozoic metamorphic rocks and Proterozoic through Paleogene granitoids. The PVF covers an area of approximately 60 by 55 km, and includes more than 400 well-preserved cinder cones and vents and eight maar craters. It was active from about 1.7 Ma until about 13 ka. We have used the ages and magnetic polarities of the volcanic rocks, along with mapped magnetic anomalies and their inverse modeling to determine that the Pinacate Volcanic Field was formed during two volcanic episodes. The oldest one built the Santa Clara shield volcano of basaltic and trachytic composition, and occurred during the geomagnetic Matuyama Chron of reverse polarity, which also includes the normal polarity Jaramillo and Olduvai Subchrons, thus imprinting both normal and reverse magnetization in the volcanic products. The younger Pinacate series of basaltic composition represents monogenetic volcanic activity that extends all around the PVF and occurred during the subsequent geomagnetic Brunhes Chron of normal polarity. Magnetic anomalies toward the north of the Santa Clara volcano are the most intense in the PVF, and their inverse modeling indicates the presence of a large subsurface body magnetized in the present direction of the geomagnetic field. This suggests that the magma chambers at depth cooled below the Curie temperature during the Brunhes Chron. © 2015 Elsevier B.V.
Filiaciones:
García-Abdeslem J.:
División de Ciencias de la Tierra, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Carretera Tijuana-Ensenada No. 3918, Fraccionamiento Zona Playitas, Ensenada, Baja California, 22860, Mexico
Calmus T.:
Univ Nacl Autonoma Mexico, Inst Geol, Estn Reg Noroeste, Hermosillo 83240, Sonora, Mexico
Estación Regional del Noroeste, Instituto de Geología, Universidad Nacional Autónoma de México, Blvd L.D. Colosio S/N y Madrid, A.P. 1039, Hermosillo, Sonora, 83240, Mexico
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