New Mexico Geological Society Annual Spring Meeting — Abstracts

The Nogal Canyon caldera is the southernmost caldera that formed the San Mateo Mountains. Mt. Withington (27.4 Ma) and Bear Trap Canyon (24.4 Ma) calderas are north of the Nogal Canyon caldera. Six peaks in the southern range exceed 3000 m in elevation: Vicks Peak (3287 m), San Mateo Mountain (3092 m), San Mateo Peak (3090 m), West Blue Mountain (3287 m), Blue Mountain (3142 m), and Apache Kid Peak (3063 m) and are remnants of the resurgent Nogal Canyon caldera. The Vicks Peak Tuff (28.4 Ma), granite intrusions and associated rhyolite and quartz latite flows and domes erupted from this caldera. The Vicks Peak Tuff is >490 m thick and is overlain by >550 m of rhyolite (Lynch, 2003). The estimated diameter of the caldera is 25 km and Lynch (2003) estimated the total volume of the Vicks Peak Tuff as 1816 km³. Re-interpretation of past studies and recent mapping by this author in the southern San 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.