Paper No. 35-4
Presentation Time: 8:30 AM-6:00 PM
THE LARAMIDIC CERRO BACHOCO INTRUSIVE AND RELATED DIKES, SONORA, MEXICO
The Cerro Bachoco forms part of the Sierra Espinazo Prieto which are a set of hills and mountains NNW primary orientated in the central region of Sonora, Mexico, included in the Basin and Range physiographic province, which occupies must of the southwestern part of the United States and extends all the way into the northwestern Mexico. The Cerro Bachoco Intrusive outcrops in the NW urban part of Hermosillo as an exposed Granite-Granodiorite intrusive cut by lamprophyric dikes that were synchronous with the normal faulting associated with the Basin and Range extensional environments, hence the indistinctive NNW striking of most of the structures that were measured. These presumptively Cretaceous-Paleocene intrusions present a variation of compositions that leads us to define it as a Granite-Granodiorite intrusive. The mid-Tertiary lamprophyre swarms also present an extensive composition showing strong cal-alkaline characteristics and abundant biotite and hornblende minerals. The aim of this work is to define and characterize, by appropriate study methods like extensive petrographic analyses and the use of a portable X-ray fluorescence spectrometer, not only the petrological aspects of the intrusions and the lamprophyric and felsic dikes within them, but also its relation to the Basin and Range province and correlation of these intrusives with others in the central Sonora region.