EVAPORITES AND BRINES 



201 



Table 42. — Ma/rine evaporite deposits of the United States — ^Continued 



Age and unit 



Thickness 

 (feet) 



Evaporite 

 mineral 

 recovered 



XXX 



Wells Formation -- X 



Panthex- Seep Formation X X 



Pennsylvanian: 



Hermosa Formation X X 



Eagle Valley Evaporite X X 



Mississippian or younger: 



Gypsum-bearing rocks, undifferentiated X X 



Mississippian: 



Big Snowy Group (of formation rank in SW X X 



Montana and Idaho). 

 Otter Formation X X 



Kibbey Formation X X 



Charles Formation 



Wareaw and St. Louis Limestones X 



St. Louis Limestone X 



Maccrady Shale X 



Michigan Formation X 



Devonian : 



Three Forks Formation 

 Souris River Formation 



Prairie Formation 



nd Potlatch Anhydrite. 



Cedar Valley and Wapsipinicon Limestones X 



Detroit River Group (of formation rank in X 



Indiana according to Shaver and others, 1970). 

 Silurian : 



Salina Formation X 



Ordovician : 



Red River, Stony Mountain, and Stonewall of __ X 



Kindle (1914) Formations. 



Joachim Dolomite equivalent — X 



Precambrian : 



Grenville Series X X 



6,000 

 1.000 

 60(7) 



50 



125 

 200 

 250(7) 



45-0 



I.IOO 

 4.000 



Denver and Williston basins (Colorado, 



Nebraska, North and South Dakota, 



and Montana). 



Southeastern Idaho and northern Utah 



Ore Grande basin (southern New Mexico) 



Paradox basin (Colorado and Utah) Sylvite. 



halite. 

 Eagle basin (western Colorado) 



Cordilleran eugeosyncline (Chichagof Island. 



Alaska). 



Northern Rocky Mountain shelf (Montana, 



Idaho, and Wyoming). 

 Williston basin and Northern Rocky Moun- 



tain shelf (Montana and North and South 



Dakota). 

 Williston basin and Northern Rocky Moun- 



tain shelf (Montana and North and South 



Dakota). 

 Williston basin and Northern Rocky Moun- — - - 



tain shelf (Montana and North and South 



Dakota). 

 Northeastern shelf of Forest City basin Gypsum. 



( Iowa ) . 

 Illinois basin (Indiana, Illinois, and Do. 



Kentucky). 



Appalachian basin (Virginia) Gypeum, 



halite. 

 Michigan basin ( Michigan ) Gypsum. 



Northern Rocky Mountain shelf (Montana) __ 



Williston basin (Montana and North and 



South Dakota). 

 Williston basin (Montana and North and (Halite and 



South Dakota). sylvite re- 



covered in 

 Canadian 

 section of 

 basin ) . 

 Northeastern shelf of Forest City Gypsum. 



basin (Iowa). 

 Michigan basin (Michigan, Ohio, and Halite. 



Indiana). 



Appalachian and Michigan basins (New Gypsum, 



York, Pennsylvania, West Virginia, halite. 



Ohio, and Michigan). 



Williston basin (Montana and North and -_—-__ 



South Dakota). 



Williston basin (Montana and North and 



South Dakota). 

 Illinois basin (Illinois) 



Northwestern Adirondack Mountains (New 



York ) . 



potassium minerals are present in some. Evaporites 

 typically form stratified rock units that extend tens 

 and even hundreds of miles and attain thicknesses of 

 several thousand feet (Pierce and Rich, 1962; With- 

 ington, 1962). Many deposits occupy areas that were 

 part of the continental shelf and that extend into 

 areas that were part of an adjacent synclinal trough. 

 Locally, along the continental margin and elsewhere, 

 great masses of halite and associated evaporites have 

 intruded overlying sedimentary strata to form salt 

 domes and other diapiric structures. Both bedded and 

 domal deposits of marine evaporites are known to 

 contain potassium ores, and they are also important 

 sources of gypsum, anhydrite, salt, sulfur, and other 

 commodities (Stewart, 1963; Braitsch, 1971). 



All marine evaporites are thought to have been 

 formed by evaporation of sea water in barred basins 



or on broad shelf areas where circulation was re- 

 stricted. The dominant rocks formed in this manner 

 were limestone, dolomite, gypsum or anhydrite, 

 halite, and the rocks containing potassium minerals. 

 Within most evaporite basins, these rocks are ar- 

 ranged in broad belts or facies that reflect the chang- 

 ing depositional environment between open sea and 

 land ; limestone or dolomite facies lie in the areas 

 that contained the least saline water, and they grade 

 into gypsum or anhydrite facies, then to halite 

 facies, in areas that contained successively more 

 saline waters. Red beds commonly represent the 

 nearshore accumulation of elastics. Economic con- 

 centrations of potassium minerals represent the final 

 stage of evaporite deposition and wherever present 

 lie within the halite facies (Mattox and others, 1968 ; 

 Hite, 1970). 



