Deposit Type
The geology of the potash-bearing beds of the Carlsbad area has been well documented. Overall, the potash-bearing beds may be described as bedded sedimentary rocks, deposited across the Delaware Basin and Northwest Shelf backreef from the Capitan Reef. The depositional sequences that developed in the Salado Formation consist of repetitive cycles that can be recognized by changes in mineralogy, sedimentary textures, and structures. Two types of cycles are differentiated Type I and Type II. A complete Type I cycle ranges in thickness from 3 ft to 33 ft and consists of (in ascending order):
• A basal, mixed siliciclastic and carbonate mudstone
• Laminated to massive anhydrite-polyhalite
• Halite
• Halite with mud (argillaceous halite)
Type II is a thinner, less complete sequence and consists of halite that grades upward into argillaceous halite (Lowenstein 1988). The anhydrite-polyhalite beds are laterally continuous over large distances and are used as marker beds for correlation. Potash beds are not included in these sequences because potash is secondary and formed later than the basic depositional sequence.
The HB Mine, which was formerly mined on the 1 and 3 ore zones (Barker and Austin 1999), has been flooded and is currently being solution mined with brines to obtain potash from the remaining pillars.
Mineralization
In the Carlsbad Area, the potassium minerals, in order of decreasing abundanc ........
