Stratigraphy of the Mississippian Leadville Dolomite, Gilman to Leadville, Colorado: Redefinition of the Castle Butte and Red Cliff Members
David W. Beaty, Robert J. Johansing, Tommy B. Thompson, 1988. "Stratigraphy of the Mississippian Leadville Dolomite, Gilman to Leadville, Colorado: Redefinition of the Castle Butte and Red Cliff Members", Geology and Mineralization of the Gilman-Leadville Area, Colorado, T. B. Thompson, David W. Beaty
Download citation file:
The stratigraphy of the Leadville Dolomite has been much more completely characterized than previously possible through study of more than 50 drill cores in the area between Leadville and Gilman, Colorado. Data from these cores, supplemented with literature descriptions and limited outcrop observations, leads to three conclusions. First, there are three major unconformities associated with the Leadville (M-l through M-3 in order of decreasing age). M-l and M-3 are at the base and top of the Leadville, respectively; M-2 is within the Leadville. Two of these unconformities (M-2 and M-3) are very well developed throughout the Leadville-Gilman area, and have been recognized in the surrounding region; M-1 is less well developed and/or of more local extent. The M-2 surface is locally associated with distinctive lithologies (pink breccia at Gilman, black shale at Mt. Sherman) which form critical marker beds. Second, a well- defined lithostratigraphy can be identified by classifying the dolostones of the Leadville on the basis of mean dolomite grain size. The number of beds at each locality is typically 10-15, and eight of these beds can be consistently traced throughout the Gilman-Leadville area. Third, the definition of the Castle Butte and Red Cliff Members of the Leadville proposed by Nadeau (1971) is ambiguous, and has led to inconsistent results when applied away from his reference sections.