Tectonic Development of the Southern Sangre de Cristo Mountains, New Mexico

About this guidebook

The 1990 New Mexico Geological Society Fall Field Conference tours the Moreno Valley area of the southern Sangre de Cristo Mountains after a hiatus of 34 years. Remarkably, Elmer Baltz, who wrote much of the road log for the 1956 trip (when this year’s editors ranged from -2 to +3 years old, Guidebook 7) has written a log for this year’s guidebook. This year we visit three major physiographic provinces: the Sangre de Cristo Mountains of the Rocky Mountains, the Rio Grande rift and the Raton Basin of the Great Plains. This diversity is well -represented in the broad spectrum of guidebook papers. The Sangre de Cristo Mountains are the most prominent topographic feature in the state, containing the highest point in New Mexico (Wheeler Peak) and several of the next -highest peaks. The Proterozoic rocks of the Sangres are presently the focus of intense study and debate concerning the nature and timing of large-scale Proterozoic tectonic/metamorphic events. The mountains are also rich in metallic mineral deposits, and the responsible extraction of these resources is currently an important and provocative environmental issue. Investigations into the Cenozoic history of the Sangre de Cristo Mountains include such exciting topics as the cooling (uplift) history of the range, the very complex Tertiary volcanic/plutonic geology and the nature of enigmatic intramontane basins such as the Valle Vidal, Moreno Valley, Mora Valley and Rociada Valley. The basins adjacent to the mountain range are the focus of numerous research projects. Studies along the eastern flank of the Rio Grande rift have revealed detailed information on the neotectonics and seismicity of the range -front faults. The Raton basin, with its well-exposed Mesozoic-Cenozoic stratigraphic section, is the subject of several papers dealing with coal resources, mine reclamation, coal-bed methane resources, basin analysis and the K-T boundary. The first-day road log is from Red River to Questa, Costilla, Valle Vidal, Cimarron and Philmont. The second-day road log is from Philmont to Cimarron, Eagle Nest, Elizabethtown and Angel Fire. The third-day road log is from Angel Fire to Las Vegas via Black Lake, Guadalupita, Mora, Rociado and Sapello. There are three supplemental road logs: one from Red River along Pioneer Canyon, another from the intersection of US-64 and NM-434 near Angel Fire, across Palo Flechado Pass to Taos, and one that details the pre-meeting trip to the Moybdenum Mine at Questa.