Abstract

Lower Permian strata are conformable to erosionally unconformable on Pennsylvanian and locally older rocks in central New Mexico. Southward from the latitude of Albuquerque to the southern part of central New Mexico near Las Cruces there is a gradual transition from continental red beds near Albuquerque, to intertongued marginal marine strata and red beds west of Ash Canyon in the southern San Andres Mountains, and to marginal marine and marine basinal facies south of Las Cruces.

East of Albuquerque, Abo red beds overlie Pennsylvanian strata. Near Abo and southward to the Oscura Mountains, Lower Permian strata are interbedded red beds and marine limestones of the Bursum facies, overlain by Abo red beds. Southward in the northern and central San Andres Mountains, marine limestone and shale of the Hueco Formation form the basal Permian beds, gradationally overlain by the Abo red beds, with the Hueco thickening southward as the Abo thins.

In the southern San Andres-Dona Aña-Robledo Mountains area, the Abo consists of only red bed tongues in the upper part of the Hueco Formation, and the Hueco is a complex of shallow marine, basinal marine, and reefoidal facies related to the last stages of the Orogrande basin. Basinal Woflcampian facies in the southern San Andres, Dona Aña, and Organ Mountains and south of Las Cruces indicate a previously unknown southern and western extension of the Orogrande basin.