New Mexico Geological Society Annual Spring Meeting — Abstracts

The Red River Mining District is centered on the town of Red River, nestled within the Sangre de Cristo Mountains of northern New Mexico. Past production from the district is minimal with sporadic activity from 1890 to about 1940.

Precambrian crystalline rocks are overlain by a variable thickness of andesitic to rhyodacitic volcanic rocks of the Latir volcanic field, dated at 26 to 35 m.y. The south and southeast ring fracture zone of the recently recognized Questa caldera (Lipman, 1981) has localized the intrusion of three extremely altered and mineralized granitic plutons along Red River and date at 22 to 23 m.y.

Precious metal mineralization of the Red River District forms an arcuate pattern a few miles outside the ring fracture zone peripheral to the late mineralized intrusives of the Questa caldera. Most mineralization is associated with quartz-cemented breccia zones or finely banded, massive or vuggy quartz veins. Many veins have argillically altered and weakly silicified and mineralized envelopes. Vein trends are generally east-west or north-south, are steeply dipping, and may be related to concentric ring fracture zones and radial faults associated with the Questa caldera. Silver:gold ratios are typically 80:1 in mineralized zones. Known ore minerals are native gold, pyrargyrite, and chalcopyrite.

Fluid inclusion studies indicate that boiling occurred. These studies also suggest a positive correlation between inclusion temperature and associated precious metal grades. Precious metal mineralization in the district may be related to the molybdenum deposits at Questa.