New Mexico Geological Society Annual Spring Meeting — Abstracts

Triassic strata exposed in the Hubbell Springs fault zone pertain to the Moenkopi (?) and Chinle Formations. At least 10 m of pale brown, brownish grat and pale red, fine-grained, micaceous, crossbedded sandstone 1.4 km south of Ojo Huelos lithologically resemble Moenkopi strata in the Lucero uplift and may be assigned tentatively to that unit. Just south of Ojo Huelos (34° 43' 46" N; 106° 46' 42" W) the approximately 13 Formation. The lower 5.6 m of these strata consist of red, gray and yellowish orange jasper and chert pebbles (maximum diameter = 5 cm) in a matrix of sandy siltstone that is mottled red, gray, yellowish orange and reddish purple. On a lithologic basis, we correlate thses strata with the "mottled strata" and Shinarump Member of the Chinle Formation. Above these strata are 7.4 m of intervedded pisolitic and fenestrate, ostracodal limestone and yellowish gray sandy mudstone. These strata may correlate with part of the Monitor Butte Member of the Chinle Formation. They contain Late Triassic fossils that inlcude the skull of a metoposaurid labyrinthodont, phytosaur teeth, a microfauna of fish teeth, including the freshwater shark Lissodua cf. L. humblei, and ostracodes assignable to two specoes of Darwinula and to Gerdalia cf. G. triassica.