Abstract

The Orogrande Basin is a Late Pennsylvanian — Early Permian depositional feature in south-central New Mexico (Figure 1). If arbitrarily outlined by the 2,000-ft isopach thickness of Pennsylvanian rocks, it is roughly 40 mi wide and extends from about the junction of Sierra, Lincoln and Otero counties, southward for more than 110 mi into westernmost Texas. The Orogrande Basin was named by Pray (1959). It had been previously noted by Thompson (1942) and others, with regional descriptions by Kottlowski (1960, 1963, 1965) and Wilson (1967). As such, it is almost contiguous with the present day Tularosa and Hueco Basins but superb outcrops of the Upper Pennsylvanian basinal facies are found in the San Andres, Organ and Franklin Mountains which bound these present-day structural basins on the west.

The region is the northeast part of the Basin and Range Physiographic Province with the eastern edge the Sacramento Mountains, and its southern extension of Otero Mesa and the Hueco Mountains being part of the Sacramento Section. The Tularosa-Hueco Basins and the areas to the west (Hawley, 1978) are in the Mexican Highland Section of the Basin and Range Province. It is a land of contrast with the heavily timbered Sacramento and Sierra Blanca Mountains on the east, rising to over 9,000 ft in many areas and over 12,000 ft at Sierra Blanca; then dropping off abruptly as much as 8,000 ft into the Tularosa Basin with its internal drainage, playa lakes and gypsum sand dunes. For the most part, the San Andres, Organ and Franklin Mountains are stark bare-rock ridges with strata of the San Andres Mountains dipping westward into the Jornada del Muerto syncline. The western alluvial fans of the Organ and Franklin Mountains are intersected by the Rio Grande Valley.

Essentially the entire San Andres range, part of the Organ Mountains and the central and western part of the Tularosa Basin are within White Sands Missile Range. Considerable parts of the Hueco Basin are in various ranges within the boundaries of Ft. Bliss; thus, much of the area is overseen by the military.

The streams from Sierra Blanca and the Sacramento Mountains empty westward into the Tularosa Basin where their flood waters are soaked up by the deep alluvial deposits and shifting sand dunes. Flood waters from the San Andres Mountains end up mainly in Alkali Flat and Lake Lucero, although the northwest part of the Tularosa Basin is drained by Salt Creek which flows southward to Alkali Flat.