FRUITLAND COAL STRIKE-PARALLEL FACIES HETEROGENEITIES AND UNCONFORMITY BETWEEN THE PALEOCENE OJO ALAMO FORMATION AND THE UPPER CRETACEOUS KIRTLAND SHALE, FRUITLAND FORMATION AND PICTURED CLIFFS SANDSTONE, SOUTHERN ARCHULETA COUNTY, COLORADO

The regressive sequence of the Campanian Fruitland Formation was observed thinning to zero coal thickness near the Colorado-New Mexico border in the San Juan Basin of southern Archuleta County. In 2012 Colorado Geological Survey geologists mapped and identified thinning and disappearance of the Animas Formation, the Kirtland Shale, and the Fruitland Formation beneath an unconformity with the overlying Ojo Alamo Formation. This unconformity is due to local Laramide uplifts only along the eastern part of the rim of the San Juan Basin east of the Southern Ute Indian Reservation. Data from 23 measured sections collected along a 40-kilometer transect geologic map documents the Ojo Alamo down cutting into the units beneath the unconformity. Lateral changes in Fruitland Formation net coal thickness indicate thinning in a west to east profile but lithologic continuity still reflects the overall progradational setting of the Cretaceous Interior Seaway. At a point where the Pictured Cliffs Sandstone is in contact with the Ojo Alamo Formation there is a series of Tertiary Dikes that cross-cut all of the Upper Cretaceous units emanating from a 100 meter thick mid-Tertiary sill capping Archuleta Mesa, previously the home of paranormal alien activity, but unverified through this mapping effort.