Exhumed mid-Miocene volcanic field in the Tesuque Formation, northern Espanola Basin, New Mexico
— S. Judson May

A small field of basaltic tuff rings, cones, minor flows, and dikes is locally exposed for a distance of 20 km between the town of Ojo Caliente and the lower El Rito Creek area in the northern Espanola Basin (Fig. 1). The field is one of the few interruptions in a mid-Miocene volcanic lull identified throughout much of the Rio Grande rift (Chapin, 1979). These tephra eruptions occurred during deposition of the middle Chama- El Rito Member of the Tesuque Formation and are closely associated in terms of mineral and textural composition, stratigraphic position, age, and possibly eruptive mechanism. North—northeast trending dikes and minor growth faults contemporaneous with volcanism imply a local N70W-oriented axis of least principal stress during mid-Miocene time. A possible genetic relationship with the Hinsdale Basalt (of Lipman and Mehnert, 1975) is suggested on the basis of approximately similar mineralogy, stratigraphic position, and age.