Paleokarst-Controlled Ore in Central Colorado
We propose that many Tertiary man to orebodies typical of Leadville and adjacent districts of Central Colorado (northern Sawatch range and Mosquito range) are modifications to pre-existing mineralized paleokarst cave systems (Tschauder and Landis, 1985; Landis and Tschauder, 1985). Major karst cave development occurred in this region during mid- to late- Mississippian time. Cave breccia mineralization (as an integral part of cave fill) is observed to dominate in Paleozoic caves located away from the influence of Tertiary intrusions (Breece Hill Center, Leadville; Buckskin stock, Alma district). Most data and many observations on the nature of this Paleozoic cave breccia mineralization are based upon access in the Sherman mine to the east of the inferred Leadville paleokarst system. However, the overprint of Laramide through mid-Tertiary ore deposition associated with intrusive centers has obscured much of the evidence for earlier cave-hosted mineralization. Tertiary mineralization in the Leadville district that we suggest exhibits and preserves features typical of cave systems include the orebodies of Fryer Hill, Downtown, Carbonate Hill, Iron Hill-Rock Hill, Julia Fiske, and Resurrection groups of mines. Additional mineralization occurs in cave systems of nine districts on the north and east slopes of the Sawatch Range from Redcliff-Eagle to Mount Lincoln in the Alma district, and then south 25 km to Weston Pass, and in a zone of discontinuous mineralization more than 50 km long on the west slope, from north of the Aspen district south into Gunnison County. Some Tertiary massive sulfide mantos typical of the Leadville district mineralization are better understood by recognizing their possible karstic cave control and Paleozoic cave breccia progenitor mineralization.