Nogal Canyon caldera, southern San Mateo Mountains, Socorro County, New Mexico; A progress report

Mateo Mountains has refined history of the caldera. Some of the northern parts of the caldera remain unmapped. Stratigraphic relationships indicate that the eruption of the Vicks Peak Tuff was followed by intrusion of the granite of Kelley Canyon and rhyolite of Alamosa Canyon, within <0.42 Ma (Lynch, 2003) in the western part of the caldera. Geochemical studies confirm they were from the same source. The Springtime Canyon Formation overlies the Vicks Peak Tuff and consists of rhyolite, quartz latite and latite flows and associated tuffs erupted along the eastern boundary, probably during this time period, but dating is required. Rhyolite dikes and small rhyolite domes erupted along the southern and northern boundaries and could be related to the caldera. The northern boundary of the caldera is partially concealed by the formation of the Mt. Withington caldera and eruption of the Vicks Peak Tuff and younger rhyolites. However, San Juan Peak is along the northeastern boundary, where an undated peralkaline rhyolite flow and dikes overlies Vicks Peak Tuff, and probably is one of the last eruptions associate with the caldera. The caldera was offset locally by younger Basin and Range faults (i.e. Rock Springs-Priest, Indian Peaks, Rhyolite, Dark Canyon, Bell Mountain faults). The San Jose mining district (Au, Ag, Cu) lies within the caldera along these Basin and Range faults, and associated hydrothermal alteration has made stratigraphic correlations difficult.