The Beeman Formation (Upper Pennsylvanian) of the Sacramento Mountains, New Mexico: Guide to the Dry Canyon area with discussion on shelf and basin responses to eustasy, tectonics, and climate
William D. Raatz and J. A. (Toni) Simo
The Beeman Formation is an understudied Upper Pennsylvanian (Missourian, lower Virgilian), cyclic, mixed terrigenous clastic/carbonate unit that crops out in the Sacramento Mountains of south-central New Mexico providing three-dimensional dip-and-strike outcrop perspectives. The Dry Canyon area offers easily accessible exposures to the most basinward deposits of the upper Beeman Formation. Although thin, offshore, diastemic dark shales are present, the bulk of deposits in Dry Canyon consist of restricted high-energy limestones with abundant evidence for subaerial exposure. High-resolution sequence stratigraphy is possible within the Dry Canyon basin area and from the basin onto the shelf through correlation of maximum flooding surfaces, exposure surfaces, and biostratigraphy. Shelf deposits (e.g., Alamo Canyon) are composed of cyclic, massive, open-marine limestones separated by exposure surfaces. The paradoxical relationship of the basin deposits being dominated by high-energy, shallow-water restricted deposits and the shelf being dominated by open-marine limestones, a phenomenon here termed "inverse sedimentation," results from the interaction of high-frequency sea-level changes and basin geometry. Glacio-eustasy was responsible for most high-frequency vertical facies changes, while tectonics and climate controlled longer term trends in basin geometry and sediment type/paleosol development.
- Raatz, William D.; Simo, J. A. (Toni), 1998, The Beeman Formation (Upper Pennsylvanian) of the Sacramento Mountains, New Mexico: Guide to the Dry Canyon area with discussion on shelf and basin responses to eustasy, tectonics, and climate, in: Las Cruces Country II, Mack, G. H.; Austin, G. S.; Barker, J. M., New Mexico Geological Society, Guidebook, 49th Field Conference, pp. 161-176.