Named for extensive exposures in the Superstition Wilderness area, Superstition Mountains, Pinal Co, AZ in the Basin-and-Range province. Occurs in the McDowell Mountains to west in Maricopa Co, and in San Tan Mountains to southwest in Pinal Co. Lies within the 375-sq-mi interior of the Superstition cauldron. Consists of quartz latite ash-flow tuff. Divisible into three newly named members (oldest to youngest)--Siphon Draw, Dogie Spring, and Canyon Lake Members--that are 3,379 ft thick. The Siphon Draw has a 24.5 +/-0.5 m.y. (at top) and a 24.2 +/-0.9 m.y. (at base) F-T age on zircons. The Dogie Spring has a 18.4 +/-0.6 m.y. date by K-Ar method on biotite. The Canyon Lake has an age of 14.9 +/-0.8 m.y. by F-T dating on zircons. Geologic map; columnar section. Miocene age. Is older than some dacite domes, lavas, and autoclastic breccias [whose age is not stated]. Intruded by some quartz latites. Overlain by unnamed rhyolite gravels.

Source: GNU records (USGS DDS-6; Denver GNULEX).

Superstition Tuff of Stuckless and Sheridan (1971) is adopted. Age is Miocene.

Source: GNU records (USGS DDS-6; Menlo GNULEX).