Circular 18—Geology and ore deposits of red river and twining districts, taos county, new mexico)

Compiled by C. F. Park and P. F. McKinlay, 1948, 35 pp.

The Red River and Twining districts in the Sangre de Cristo Mountains of northern New Mexico comprise rocks in age from Proterozoic to Tertiary. The oldest rocks are hornblende gneiss, quartz mica schist, quartzite, and amphibolite. In the vicinity of Gold Hill intensely folded tacl schists, chlorite schists, quartz mica schists, and metamorphic gabbros crop out.

Interbedded limestones, shales, and grits in the southeastern part of the area contain fossils of Pennsylvanian age. These strata are equivalents of parts of the Magdalena Group of other areas of New Mexico. Flows and intrusives thought to be of Tertiary age extend over most of the northern part of the area.

Ore minerals occur in quartz veins and shear zones in the metamorphic rocks, in quartz veins and silicified breccia zones in the volcanic rocks, and in contact metamorphic zones on the margins of granodiorite bodies. In the past , most of the prospecting and mining in the Red River and Twining districts was for gold and copper, but no extensive deposits have been found. The only active mine in the region is the Questa molybdenum mine, which is located 6 miles west of Red River.