The Cordilleran Overthrust belt of Laramide age (Late Cretaceous-early Tertiary) trends west-northwesterly through southwestern New Mexico and is characterized by flat-lying thrusts and subordinate closely compressed folds. These Laramide structures and the rocks deposited prior to and during Laramide deformation are exposed as small patches surrounded by younger postorogenic rocks, including voluminous volcanic rocks of middle Tertiary age and late Cenozoic clastic sediments. Middle Tertiary volcanism involved eruption of silicic ash-flow tuffs from several large cauldrons in southwestern New Mexico. Basin-range extensional block faulting occurred in late Cenozoic time, and the range-marginal faults truncate the cauldrons and the Laramide structures.

Although the thrust belt in southwestern New Mexico has similarities to the thrust belt in northern Utah and western Wyoming where commercial accumulations of hydrocarbons have been found, there are also marked differences: volcanism is much more intense, and younger basin-range block faulting has probably at least partly destroyed thrust-belt traps in New Mexico, whereas this is less likely in Wyoming and Utah. Also, in New Mexico the most likely source and reservoir rocks are of Paleozoic age and hence are much older than the traps which are probably partly Laramide in age and partly late Cenozoic; in Wyoming and Utah the source rocks are probably Cretaceous and the traps are Late Cretaceous-early Tertiary and thus are closer in age. Lack of continuity of exposure of structures alon strike, coupled with greater structural complexity, makes it more difficult to apply geophysical techniques, particularly seismic, to exploration for hydrocarbons in the New Mexico part of the thrust belt than in the Wyoming-Utah part. An encouraging aspect is that several wells drilled in New Mexico encountered shows of oil and gas within the limits of the thrust-faulted area. The density of drilling in this part of New Mexico is analogous to the situation in western Wyoming and Utah prior to the discovery of Pineview field.