In a section measured at Mogollon, Catron Co, NM, Basin-and-Range province, detailed magnetic studies reveal a simple pattern: Cooney Formation and Whitewater Formation [author is referring to Whitewater Creek Member of Cooney Tuff] are older than the other units (Bikerman, 1972), and they are consistently reversely magnetized. They are overlain by Pacific Quartz Latite, which correlates approximately with Apache Spring Quartz Latite. Pacific Quartz Latite is very stable magnetically, but it has an unusual direction of magnetization--therefore, it probably cooled rapidly during a time when the field was reversing. Both in its direction of magnetization and in its magnetic properties, Pacific bears a surprising similarity to Taylor Creek Rhyolite, but is distinctly older. Magnetostratigraphic position of Taylor Creek unit within a preliminary model of the middle Tertiary paleomagnetic reversal pattern is depicted on fig. 4; Cooney, Whitewater, Apache Spring, Mineral Creek, Fanney, and Last Chance units depicted on fig. 5.

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

Redescribed--name changed from Cooney Latite Tuff to Cooney Tuff. Divided into Whitewater Creek Member (base) and Cooney Canyon Member (new). Cooney Canyon Member was formerly the upper quartz latite member. Type section designated as in S1/2 sec 21, T10S, R19W, Catron Co, NM, Basin-and-Range province. Is a rhyolite to quartz latite compositionally zoned ash-flow tuff, at least 600 m thick. Whitewater Creek has a Zr fission-track age of 31.8 +/-2.8 m.y. Cooney Canyon has a K-Ar biotite age of 32 +/-1.5 m.y. Eruption of Cooney may have initiated cauldron collapse in Mogollon Mountains region. Assigned to Oligocene.

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

Cooney Canyon Member has yielded a 33.1 +/-1.5 m.y. age (biotite). Whitewater Creek Member has yielded a 31.8 +/-2.8 m.y. age (zircon). Unspecified parts of Cooney have yielded ages of 34 +/-2 (plagioclase), 24.3 +/-0.8 m.y. and 33.7 +/-1.0 (biotite), and 33.1 +/-2.8 (zircon). [These ages are Oligocene.] Was sampled in Catron and Grant Cos, NM and Greenlee Co, AZ in the Basin-and-Range province.

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