Date of Award


Degree Name

Master of Science


Geological and Environmental Sciences

First Advisor

Dr. Mohamed Sultan

Second Advisor

Dr. Richard V. McGehee

Third Advisor

Dr. W. David Kuenzi

Fourth Advisor

Dr. John Grace


South Antelope Pass, unit-T5, San Simone Valley, Animas Valley

Access Setting

Masters Thesis-Open Access


Volcanic activity during the middle and late Tertiary has been recorded in the mountain ranges of the southwestern United States and northern Mexico and the two provinces of prominent volcanic activity, the Sierra Madre Occidental and the Mogollon Plateau, dominantly rhyolitic in composition, are connected by the Peloncillo Range. The predominant rock chemistry of the south Antelope Pass area is “rhyolitic”; however, lava rock types dominate over welded tuff rock types of the two provinces. There is a limited pre-Tertiary rock record of limestones and sandstones in the northeastern part of the study area. The rest of the study area is Tertiary and Quaternary volcanic rocks and alluvium. The first episode of deformation in the area is associated with the deposition of Unit-T5 lava where the rock unit flow direction was modified, but the source of the lava could not be located. The second episode of deformation is associated with Basin and Range mountain building in mid to late Tertiary, which outlined the present day north-south trending Peloncillo Range and where contemporaneous local faults occurred through the interior of the range, while there was erosion of vast quantities of material filling the adjoining basins. Late Tertiary to Recent time had limited basalt flows in both the San Simone and Animas valleys. No evidence of economic mineralization was identified.