Geomorphology of the northern Tularosa Basin, south central New Mexico, with particular attention to uncommon surficial features
D. W. Love, B. D. Allen, and R. G. Myers
The floor of the northern Tularosa Basin between the Oscura Mountains and Alkali Flat consists of a southsloping gypsum-alluvial discharge plain with distal alluvial fans, stream valleys, springs and marshes, eolian blowouts, loess, and the Carrizozo Malpais lava flow. Episodic deflation of large blowout basins as much as 8 m deep and several km long are a major influence on base levels and the resulting geomorphology of the northern basin. Holocene blowouts have expanded and deepened as shallow (perched) ground water levels have declined. The surficial expression of clastic depositional and erosional features ("clastic world") is typical of the semiarid Basin and Range, and includes features such as multi-level piedmont slopes, and bolson floor and eolian deposits.
In contrast, large areas of the northern Tularosa Basin are underlain by gypsum ("gypsum world"). The gypsum accumulates by evaporation of brackish- to brine-saturated groundwater discharge and by input of eolian gypsum and siliciclastic dust. Gypsum build-up and erosion creates rare surficial features perhaps unique to the northern basin. The surficial features include (1) gypsum spring mounds from 1 to 5 m high with basal areas from tens to hundreds of square meters, (2) gypsum megamounds more than 13 m high and 1.5 km across, (3) gypsum marsh deposits 0.5 to >2 m thick covering an area of more than 50 km2 (4) raised-rim active and extinct gypsum ponds and marshes, (5) active and inactive gypsum platform marshes, and (6) a raised gypsum-levee meandering stream. Dissolution of former buildups of gypsum produces sinkholes in the gypsum megamounds and in gypsiferous basin fill.
- Love, D. W.; Allen, B. D.; Myers, R. G., 2014, Geomorphology of the northern Tularosa Basin, south central New Mexico, with particular attention to uncommon surficial features, in: Geology of the Sacramento Mountains region, Rawling, Geoffrey; McLemore, Virginia T.; Timmons, Stacy; Dunbar, Nelia, New Mexico Geological Society, Guidebook, 65th Field Conference, pp. 143-156.