New Mexico Geological Society Annual Spring Meeting — Abstracts

The Turkey Mountains, a northeasterly-trending breached anticline, are in the southern Raton Basin, northeastern New Mexico. Strata exposed include rocks of Upper Triassic to Upper Cretaceous age. Late Tertiary and Quater nary volcanic rocks of the Ocate volcanic field occur along the north, east, and southeast flanks of the mountalns. The Turkey Mountain Anticline was probably produced by a late Tertiary (1) intrusion which is not exposed at the surface, but has been penetrated by a drill hole near the crest of the anticline. Nort herly trending, alkaline lamprophyre dikes occur in the Turkey Mountains and are probably associated with the Tertiary (?) intrusion which underlies the anticline. A potassium-argon date of 15.6 ± 0.7 m.y. on biotite from one of the dikes indicates that emplacement of the dikes occurred during Miocene time.

A study of systematic joints in the Dakota Sandstone (Cretaceous), which encircles the range and has been deformed by the uplift, was undertaken in an effort to determine the deformative stress field which produced the uplift. The primary systematic joints in the Dakota Sandstone comprise a set with a mean vector of N 20° W. A secondary set, approximately orthogonal to the primary set, was observed but is not systematic, based on the statistical techniques used in this study. The systematic set appears to be associated with a regional pattern which predates the local uplift; and therefore, no relationship appears to exist between the systematic joint pattern in the Dakota Sandstone and the stress field which produced the uplift.