New Mexico Geological Society Annual Spring Meeting — Abstracts

Jasperoid-barite-fluorite-quartz-calcite mineralization of the Palm Park deposit occurs at and just below the Silurian Fusselman Dolomite-Devonian Percha Shale contact along the crest of a N.34°W. trending asymmetrical anticline. The deposit crops out over a 6,000 ft (1,800 m) by generally 200 to 600 ft (60 to 180 m) area. The ore zones average 12 ft (3.7 m) thick and contain approximately 25 to 30 percent barite and 3 to 4 percent fluorite. The Fusselman Dolomite and, to a lesser extent, the Percha Shale have been replaced by jasperoid and usually brecciated. Crustiform barite-fluoritequartz-calcite mineralization comprises the matrix of the brecciated jasperoid and fills vugs between beds that have been replaced by jasperiod.

Mineralization apparently occurred sometime during the Oligocene-Miocene time interval and was probably related to the early magmatic and (or) hydrothermal activity of the Rio Grande rift. Fractures that formed due to rift deformation and perhaps the Laramide orogeny contain jasperiod and barite stratigraphically below the breccia-and bedded-ore and probably represent the conduits used by the ascending ore fluids. The combination of the Perch a Shale and anticlinal fold acted to trap and concentrate the ascending fluids below the dolomite-shale contact, along the fold crest. Brecciation resulted from the solutioning and collapse of the host rocks as they were replaced by jasperiod. Subsequently, barites fluorite, quartzs and calcite were precipitated predominantly in open spaces between breccia fragments and bedding planes, at temperatures ranging between 163.5° and 341.0°C.

There is excellent potential for extensions of the Palm Park deposit and for the presence of similar deposits in the surrounding region.