| Basis for focus area |
Alkaline/peralkaline igneous rocks. Broad area of exposed and potential concealed REE in highly fractionated Tertiary rhyolites. Area extends from New Mexico to south of the Quitman Mountains, including the Sierra Blanca Complex, Round Top deposit, and nearby similar prospects (intrusive rhyolites with high whole rock REE); includes the Cave Peak deposit. Western boundary is the approximate edge of the Rio Grande Rift. See smaller focus areas around Round Top and Cave Peak. See McLemore (2018a) for summary of the deposits in the belt. |
| Identified resources |
Identified resources of copper, molybdenum, and niobium. |
| Production |
None. |
| Status |
Drilled and evaluated as a Mo prospect, but never mined. |
| Estimated resources |
Demonstrated and Indicated reserves (1980) were 74,374,000 mt ore, with grades of 0.255% MoS2, 0.05% WO3, 0.04% Cu, and 0.002% Sn. |
| Geologic maps |
Wiley (1972), scale 1:125,000. |
| Geophysical data |
Inadequate aeromagnetic and aeroradiometric coverage; Wiley (1972). |
| Favorable rocks and structures |
Silicic intrusions similar to other Climax-type porphyries, but more alkalic. |
| Deposits |
Cave Peak molybdenum deposit (MRDS dep_id: 10178355; USMIN Site_IDs: TX00002; TX00010). |
| Evidence from mineral occurrences |
MRDS; USMIN. |
| Geochemical evidence |
Silicic melt inclusions contain 9 to 38 ppm W, fluid inclusions contain 7 to 80 ppm W (Audétat, 2010). |
| Geophysical evidence |
Recent Rank 1 aeromagnetic and aeroradiometric data (Bultman, 2021). |
| Evidence from other sources |
Cave Peak porphyry Mo-(Nb) deposit is genetically related to a mafic, alkaline intrusion (Audétat, 2010; Urguhan, 2018). |
| Comments |
High priority to locate similar deposits in the Trans-Pecos Igneous Province/Belt. |
| Cover thickness and description |
Deposits may be present at depth in mapped sedimentary rocks or concealed by Cenozoic basin fill. |
| Authors |
Brent A. Elliott, Joshua M. Rosera. |
| New data needs |
Date fluorite throughout belt, focused mapping in certain areas, chemistry from all the laccoliths and Tertiary igneous rocks that have not been sampled and analyzed with any modern geochemistry. |
| Geologic mapping and modeling needs |
Some mapping done in the area, but incomplete, only 1:250,000 scale maps, such as Geologic Atlas of Texas regional maps and Wiley (1972). |
| Geophysical survey and modeling needs |
Have new Rank 1 geophysical data. |
| Digital elevation data needs |
Lidar complete. |
