Stratigraphic sections, depositional environments, and metal content of the upper part of the Middle Pennsylvanian Minturn Formation, Northern Sangre De Cristo Range, Custer and Saguache counties, Colorado

The calcareous upper part of the 2,000-meter-thick Middle Pennsylvanian Minturn Formation (Lindsey and others, 1985) in the northern Sangre de Cristo Range is a key stratigraphic interval for correlating rocks and mapping the structure of the range. The stratigraphy of this complex and heretofore poorly known interval is reported here in order to provide a basis for correlation among the structural blocks in the range. Inferred depositional environments of the upper part of the Minturn Formation are described briefly.

The upper part of the Minturn contains numerous occurrences of stratiform uranium and copper that were examined and sampled in order to document the concentration and distribution of metals within the established stratigraphic framework. The occurrences studied are classified according to the inferred depositional setting of the host rock in order to assess the extent of paleogeographic and paleohydrologic control of mineralized horizons.