Arizona-New Mexico Cretaceous placers

Region West, Southwest
Mineral systems
Deposit types
Critical minerals
Other minerals

Information leading to the delineation of this focus area

Basis for focus area Monazite-xenotime-bearing placers and paleoplacers: Late Cretaceous Coastal placer sandstone deposits of the San Juan Basin, New Mexico, and Black Mesa, Arizona. Focus area is based on the geologic map outlines of units from the base of the Gallup Sandstone upsectionward through and including the Pictured Cliffs Sandstone, each unit a part of the Mesa Verde Group (McLemore, 2010b).
Identified resources Identified resources of REE, thorium titanium, and zirconium. Historical production of uranium.
Production Hogback deposit shipped 8 short tons to an AEC uranium ore buying station, yielding 3 pounds of 0.02% U3O8 and 23 pounds of V2O5 (McLemore, 2010b). Sanostee identified resource.
Status Past mining for U. Past exploration at Apache Mesa (drilling in 2010), many deposits are on Indian reservations.
Estimated resources Example single deposit: Sanostee deposit (2.5 miles northwest of Sanostee, New Mexico): 3.2 million tons at 15.6% TiO2, 2.6% ZrO2, 0.12% ThO2 and minimum estimated 0.3% TREE. There are 43 known coastal placer deposits in the Gallup, Dalton, Point Lookout, and Pictured Cliffs Sandstones in the San Juan Basin, New Mexico, and the Toreva Sandstone in Black Mesa area, Arizona (McLemore, 2010b; Zech and others, 1994; Chenoweth, 1957). Few of the 43 will be as good a grade and in as an appropriate a mining situation as Sanostee, but others will be nearly as good and nearly as easy. 33 deposits in San Juan Basin (New Mexico): an estimated total resources of 4.75 million (short) tons at 12.82% TiO2, 2.07% ZrO2, and 0.10% ThO2 (Dow and Batty, 1961). U.S. Bureau of Mines studied 33 deposits in San Juan Basin; Dow and Batty (1961) estimated total resources of 4.75 million (short) tons at 12.82% TiO2, 2.07% ZrO2, 0.10% ThO2.
Geologic maps Horton and others (2017), scale 1:500,000; Strobell and others (1980), scale 1:24,000.
Geophysical data Inadequate aeromagnetic and aeroradiometric coverage. Discovery of most of the known deposits was from 1950s vintage airborne aeroradiometric surveys.
Favorable rocks and structures Transgressive (eastward prograding) sandstones of the Mesa Verde Group of Late Cretaceous age: Gallup Sandstone, Dalton Sandstone, Point Lookout Sandstone, and Pictured Cliffs Sandstone, New Mexico, and Toreva Sandstone, Arizona.
Deposits Sanostee deposit (MRDS dep_id: 10096167), Hogback mine (MRDS dep_id: 10014534).
Evidence from mineral occurrences MRDS; Dow and Batty (1961).
Geochemical evidence From Force (1991); the mineral residence of much of REE in these Late Cretaceous paleoplacers is monazite, so REE are dominated by La and Ce. Existing analyses are likely to yield a fairly reliable regression that would predict total REE from the TiO2 grades. Minimal work would probably also yield a way to predict REE from Th gamma-ray scintillometer readings.
Geophysical evidence Chenoweth (1957) reports gamma anomalies in drill wells in San Juan Basin that are likely placer deposits.
Evidence from other sources Dow and Batty (1961).
Comments Unlike the coastal placer deposits along the East Coast from southeastern Virginia to northern Florida, these are lithified sandstones, commonly firmly cemented with goethite, lesser calcite, and minor anatase or brookite. They would require drilling, blasting, and grinding, but might then yield products to fairly simple gravity separation techniques like those employed along the East Coast. Similar deposits are found throughout Cretaceous basins and sedimentary rocks from New Mexico northward to Montana. Sanostee is one of the larger deposits.
Cover thickness and description Variable by the multiple individual lenses that constitute each deposit. Most of the tonnages do have sedimentary rock cover of meters to tens of meters. With even just tens of meters, the deposits would become very poorly economic or not viable at all.
Authors Lukas Zurcher, Timothy S. Hayes, Mark E. Gettings, Virginia T. McLemore, Carson A. Richardson.
New data needs One deposit has been drilled, need to drill Sanostee, but it is on the Navajo Reservation. Need to calculate ore resources using GIS approach.
Geologic mapping and modeling needs None requested at this time.
Geophysical survey and modeling needs Not typically needed once a heavy mineral concentration is discovered; deposits have very strong directional trend that can commonly be determined from air radiometric signature: a coastal-parallel direction.
Digital elevation data needs Lidar complete in New Mexico, incomplete in Arizona, and in progress in Colorado.