The Miocene dike swarm of the Mohave Mountains, Arizona: Petrography, geochemistry, geochronology, and paleomagnetism.

摘要

Petrographic, geochemical, geochronologic, and paleomagnetic studies of Tertiary dikes in the Mohave Mountains of Arizona have been used to characterize the style and timing of detachment faulting associated with the Crossman block. Dikes in the eastern Mohave Mountains were emplaced at greater depths and altered at higher temperatures than those in the west. Associated hydrothermal circulation lasted {dollar}<{dollar}5000 years. The dikes (basalts through rhyolites) define a magmatic, calcalkaline differentiation trend. Variable degrees of crustal contamination or partial melting probably occurred. The dike swarm was intruded over a short period of time 20 m.y. ago and it cooled quickly. This dike swarm may be correlative with the Chamber's Well dike swarm in the Whipple Mountains of California. Detachment faulting was initiated prior to the intrusion of the dike swarm. Late-stage faulting was accompanied by a change in the orientation of the local stress regime.