New Mexico Geological Society Annual Spring Meeting — Abstracts

The Pennsylvanian strata exposed at Whiskey Canyon in the Mud Springs Mountains of Sierra County, New Mexico (secs. 1-2, T13S, R5W) are a nearly 500 m thick section with extensive fusulinid assemblages that M. L. Thompson first described in detail in 1942; he named the Mud Springs, Armendaris and Bolander groups and their constituent formations based on type sections in Whiskey Canyon. The base of the Pennsylvanian section is not exposed in Whiskey Canyon, and is 4 m of fossiliferous limestone of Thompson’s Apodaca Formation. The overlying Mud Springs Group consists of the Hot Springs Formation (27 m of interbedded limestone and shale) overlain by the Cuchillo Negro Formation (7.6 m of cherty limestone and coarse-grained sandstone). The overlying Armendaris Group begins with the Elephant Butte Formation (20 m of interbedded shale and limestone, with a basal Chaetetes-bearing limestone called the Warmington Limestone Member), followed by the Whiskey Canyon Limestone (44 m of very cherty, fossiliferous limestone) capped by the Garcia Formation, 59 m of interbedded limestone and shale with a prominent limestone pebble conglomerate at its base.

The overlying Bolander Group is 62 m of varied fossiliferous limestones, most nodular or cherty. Thompson did not describe the post-Bolander Pennsylvanian strata in Whiskey Canyon, but we can tentatively assign these strata to units he named in the Oscura Mountains of Socorro County. These are the Veredas Group (Coane, Adobe and Council Springs formations), 58 m of mostly cherty limestone, Hansonburg Group (Burrego and Story formations), 35 m of mostly nodular fossiliferous limestone, and the Keller Group (Del Cuerto and Moya formations), 73 m of mostly shale capped by nodular limestone. The overlying Bursum Formation is 85 m of siliciclastic red beds and interbedded limestone.

Although we can recognize the lithostratigraphic units Thompson named in the Whiskey Canyon section, the boundaries of many do not correspond to easily mapped, distinctive lithologic changes. Most of his formations are units too thin to map and/or are lithologically composite, so they are not readily recognized as distinctive lithosomes. Despite this, many of the lithostratigraphic units Thompson named can be recognized as member- or bed-rank units of utility in local and regional stratigraphy.