Mineral sources of water in evaporite sequences (salado salt and adjacent beds at the proposed waste disposal facility near Carlsbad in Lea and Eddy Counties, New Mexico)

Results of this study indicates that the Salado Salt is composed primarily of fine to coarse-grained halite with polyhalite, anhydrite, and clay minerals. Other minerals detected in small amounts include gypsum, magnesite, quartz, feldspar, sylvite, carnallite, celestite(question), glauconite, and kainite(question). Petrographic evidence (hopper crystals, and intergrowth of halite with other minerals) indicate that the Salado Salt was deposited in rather shallow water and may have been exposed subaerially at times. There must have been a major change in environmental conditions between the deposition of the Castile Formation and that of the Salado. The evidence also suggests that fluids have been able to move through the Salado Salt along beds and seams of clay and silt and somewhat along fractures. Water loss upon heating to 102 +- 50C ranges from 0.0 to 3.5 percent, considerably lower than those for Lyons, Kansas samples. Most of the dehydration water at 1000C comes from clay minerals, while at higher temperatures, polyhalite contributes. The rock units in Salado Salt seem to release much less water when dehydrated than the Hutchinson Salt rocks at Lyons. During preparation of some of the samples, H2S and possibly some natural gas were released when the samples were crushed