New Mexico Mineral Symposium — Abstracts

El Malpais National Monument was established recently by Congress. One of the outstanding features of the monument is its lava-tube systems. The concentration of tubes is so high here that Hatheway and Herring (1970) chose El Malpais as a terrestrial analog to what are believed to be similar structures called "rills" that occur on the moon.

The El Malpais tubes are also significant because of the length of many of the systems. For example, one tube system within the monument is reported to be 17.9 mi (28.6 km) long by Elston and Wohletz (1987). Such a considerable length is not believed to be typical of lava tubes in other locales. Further, the intact (cave) portions of El Malpais lava tubes are often noteworthy relative to tube lengths observed elsewhere. Four lava caves within the monument exceed one kilometer in length and one is two kilometers. Finally, the size of many of the El Malpais tubes appears to be uncommonly large. Tubes that exceed 50 ft in height and 60 ft in width are not uncommon.

Kent Carlton collected cave minerals during a 1988 lava-tube inventory and submitted them to New Mexico Institute of Mining and Technology for identification.

Chris McKee analyzed the samples by x-ray diffraction. The samples contain quartz, feldspar, calcite, thenardite, gypsum, trona, and burkeite.
 

References:

1. Elston, W. E., and Wohletz, K. H., 1987, Quaternary basalt fields of west-central New Mexico--McCartys pahoehoe flow, Zuni Canyon as flow, Zuni ice cave, Bandera crater and Zuni Salt Lake maar; in Beus, S. S. (ed.), Rocky Mountain Section of the Geological Society of America: Geological Society America, Centennial Field Guide, v. 2, pp. 431-436.
2. Hatheway, A. W., and Herring, A. K., 1970, Bandera lava tubes of New Mexico, and lunar implications: Ariz. Univ., Communications of the Lunar and Planetary Laboratory, v. 8, part 4, pp. 298-327.