Supai Salt Basin, Arizona, USAi

Regional Level Types
Supai Salt Basin	Basin
Arizona	State
USA	Country

Arkla Exploration Company identified 5 cycles of halite deposition in the Supai Formation based on regionally extensive carbonate beds. Each cycle starts with deposition of halitic mudstone and halite and ends with a fining upward sequence of siltstone and shale overlain by carbonate, which could represent flooding of the marginal and inner sabkha by marine water. Cycle 1 starts at the base of the Big A Butte Member and ends with deposition of the Fort Apache Member. Cycles 2 through 4 start at the base of the Corduroy Member and end with deposition of what Arkla referred to as the first regionally extensive dolomite below the top of the evaporite strata. Cycle 5 starts at the top of the first dolomite and ends with the deposition of regionally persistent anhydrite beds that cap the evaporite strata.

The main body of salt in the Holbrook Salt Basin occurs in the Corduroy Member of the Supai Formation. Salt beds in the Corduroy Member are most commonly 1-5 feet thick but range in thickness from inches up to 30 feet and are interbedded with mostly red to brown clayey siltstone and shale, some gray to brown carbonate, and white to gray anhydrite. Black carbonaceous shale and dark-brown to black dolomite are reported in some core descriptions. Aggregate thickness of salt in the Corduroy Member ranges up to 530 feet.

Salt in the Corduroy Member grades from very clear to muddy. Clay in muddy salt grades from finely disseminated clay to small to large irregular blebs, stringers, and bands of clay. Interbedded clay and silt generally contain thin to very irregular bands and inclusions of fine to medium crystalline salt and small anhydrite blebs. Halite generally fills fractures in the interbedded clay and silt. Anhydrite generally occurs as small to medium to occasional very large blebs and stringers in the salt.