| Basis for focus area |
Polygons modified from 1995 National Assessment (U.S. Geological Survey National Mineral Resource Assessment Team, 2002; tract CR33). Original tract from assessment encompassed Pennsylvanian through Permian redbed-type sediment-hosted Cu deposits. However, some of the area included evaporite or evaporite-bearing facies (for example, Eagle Valley Formation). Polygons were modified by removing areas with (or near) evaporite facies. Focus area outlines Sangre de Cristo, Minturn, and Maroon Formations. |
| Identified resources |
Historical production of copper, silver, uranium, and vanadium. |
| Production |
Dirty Gulch mine produced 8 t Cu and 1,460 g Ag in 1907. |
| Status |
Unknown. |
| Estimated resources |
Unknown. |
| Geologic maps |
Johnson (1969), scale 1:250,000; Scott and others (1978), scale 1:250,000; Tweto and others (1978), scale 1:250,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage. |
| Favorable rocks and structures |
Deposits occur in Middle Pennsylvanian (DesMoinesian) through Lower Permian (Wolfcampian) clastic rocks derived from erosion of the Ancestral Rocky Mountains. Stratigraphic units include Maroon, Minturn, Madera, Bursum, Naco, Sangre de Cristo, Abo, Yeso, Supai, and Cutler Formations, and these rocks constitute the permissive tract. Within these, the red bed-over-gray bed transition (Sangre de Cristo to Minturn or Madera; Abo to Bursum; Supai to Naco) is considered the best target. |
| Deposits |
Dallas Dottie prospect (MRDS dep_id: 10087413), Red Gulch district, Acme, Copper Prince. |
| Evidence from mineral occurrences |
MRDS records for 8 sediment-hosted copper-type deposits in the Trinidad and Pueblo 1:100,000-scale map areas. |
| Geochemical evidence |
Stream sediment geochemistry and panned concentrate data exist for parts of the focus area. |
| Geophysical evidence |
No data. |
| Evidence from other sources |
Deposits in this small Red Gulch district were compared to "red bed" deposits in New Mexico and Arizona by Lindgren (1908). Copper occurs as chalcocite and copper oxides (mainly malachite) in mostly Pennsylvanian-age clastic rocks. |
| Comments |
Oxidized ore with gangue barite. Note that although the permissive rocks extend through the Leadville area, all the occurrences linked to this deposit type within the focus area occur in the southernmost three segments of the mufti-part focus area. |
| Cover thickness and description |
Variable. |
| Authors |
Jane M. Hammarstrom, Joshua M. Rosera. |
| New data needs |
Geologic mapping or compilation, lidar. |
| Geologic mapping and modeling needs |
1:24,000 scale geologic mapping at over 30 quadrangles or compilation of the Craig, Leadville, Denver, Pueblo, and Trinidad 1:250,000 scale geologic maps. |
| Geophysical survey and modeling needs |
None requested at this time. |
| Digital elevation data needs |
Lidar partly available, Gunnison County is currently proposed, and portions of Pitkin County are unavailable. |
