The Carrizo Mountain stock and associated intrusions, Lincoln County, New Mexico
— David J. Pertl and Joseph C. Cepeda

The Carrizo Mountain stock in the Sacramento Mountains of south-central New Mexico is a steepsided, partly fault-bounded intrusion of rhyolite and quartz monzonite. Sills associated with the intrusion occur along the north and northwest sides. Associated plugs and dikes occur on the northwest and southeast sides where their emplacement was facilitated by pre-existing fault zones. Dikes trend N20°E to N70°E and consist of rhyolite and several types of diabase. The diabase dikes are petrographically similar to the dikes of the adjacent Capitan dike swarm. Field and petrographic study has delineated an interior zone of porphyritic equigranular quartz monzonite partially enclosed in a thin shell of rhyolite. The presence of sanidine-rimmed plagioclase in the quartz monzonite suggests that differentiation of a granitic magma may be responsible for the observed variation, although the possibility of multiple intrusions cannot be ruled out.