Bass Mine (Bass property; Asbestos Camp), Grand Canyon, Coconino Co., Arizona, USA
|Latitude & Longitude (WGS84):||36° 15' North , 112° 22' West|
|Latitude & Longitude (decimal):||36.25000,-112.36667|
|Other regions containing this locality:||Grand Canyon National Park, Arizona, USA|
|Köppen climate type:||BSk : Cold semi-arid (steppe) climate|
A former asbestos occurrence/mine located in the vicinity of Bass Ferry and 25 miles NW of Grand Canyon station. The deposit is 450 feet from the bottom of the canyon, which is 4,500 feet deep at this location.
Mineralization is in veins along bedding planes in Precambrian Bass Limestone that has been altered adjacent to diabase sills. The thickest veins occur in limestone, 3 to 15 feet below a diabase sill.
The Grand Canyon exposes an excellent section of the Carboniferous, Cambrian, Algonkian, and Archean rocks. The Algonkian is markedly unconformable with the overlying Cambrian as well as the underlying Archean, and forms a wedge-shaped mass with its edge along the canyon near its bottom and thickening rapidly to the north. The asbestos occurs in the basal portion of the Algonkian. Fifteen feet of whitish limestone overlie beds of siliceous conglomerate and fine shaly beds. This limestone contains layers and nodules of serpentine with more or less asbestos. Above the asbestos limestone comes a heavy layer of compact diabase about 200 feet thick, and above the diabase is a bed of limestone and shaly rocks similar to those immediately below the diabase. A little asbestos is seen above the diabase.
1 valid mineral.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
252.17 - 298.9 Ma
|Paleozoic sedimentary rocks|
Age: Permian (252.17 - 298.9 Ma)
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
|Serpukhovian - Early Cambrian|
323.2 - 541 Ma
|Mississippian, Devonian, and Cambrian sedimentary rocks|
Age: Paleozoic (323.2 - 541 Ma)
Description: Brown to dark gray sandstone grades upward into green and gray shale, overlain by light to medium gray or tan limestone and dolostone. This unit includes the Tapeats Sandstone, Bright Angel Shale, Muav Limestone, Temple Butte Formation and Redwall Limestone in northern Arizona, and the Bolsa Quartzite, Abrigo Formation, Martin Formation, and Escabrosa Limestone in southern Arizona. These rocks record intermittent sea-level rise and inundation in early Paleozoic time. (330-540 Ma)
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
501 - 511 Ma
|Bright Angel Shale|
Age: Cambrian (501 - 511 Ma)
Stratigraphic Name: Bright Angel Shale
Description: Green and purple-red, slope-forming siltstone and shale, and interbeds of red-brown to brown sandstone of Tapeats Sandstone lithology. Includes ledge-forming red-brown sandstone member of McKee and Resser (1945). Consists of green and purple-red, fine-grained, micaceous, ripple-laminated, fossiliferous siltstone and shale; dark-green, medium- to coarse-grained, thin-bedded, glauconitic sandstone; and interbedded purplish-red and brown, thin-bedded, fine- to coarse-grained, ripple-laminated sandstone. Includes gray, thin-bedded, fine-grained, micaceous silty dolomite in upper part of unit in western quarter of map area. Intertonguing and facies change relationships with the underlying Tapeats produce variable thickness trends. Contact with the Tapeats is arbitrarily marked at lithologic vertical and lateral transition from predominantly green siltstone and shale to predominantly brown sandstone in slope above the Tapeats cliff. Thickness is about 350 ft (107 m) in eastern quarter of map area, thickening to about 500 ft (150 m) in western quarter
Reference: Billingsley, G.H. Geologic Map of the Grand Canyon 30' x 60' Quadrangle, Coconino and Mohave Counties, Northwestern Arizona. USGS Geologic Investigations Series I-2688.