The Laramide orogeny was a mountain building event that affected the US western interior during the Late Cretaceous to Paleogene (approximately 90–45 million years ago). Many of the iconic mountains and major oil and gas producing intermontane basins of the Rocky Mountains and Colorado Plateau, such as the Wind River range in Wyoming and the San Juan Basin here in New Mexico, formed during this time as Earth’s crust was compressed. The Laramide orogeny remains a major point of controversy, as it is difficult to explain how tectonism proceeded so far into the North American plate.
Pre-Cordilleran rocks of western North America are predominantly composed of inboard, more stratigraphically coherent assemblages and more outboard assemblages with tectonostratigraphic histories obscured by extensive deformation, magmatism, and metamorphism. Inboard assemblages generally represent autochthonous deposits of the western Laurentian continental margin that formed in response to the breakup of the Rodinian supercontinent whereas outboard packages define a tectonic collage representing westward continental growth since mid-Paleozoic time . Detrital zircon U-Pb geochronology of metasedimentary strata across western North America has revealed varied sedimentary sources from both within and without the Laurentian craton that shift through time and space.
The depositional age of the Gatuña Formation in the Pecos Valley of southeastern New Mexico is poorly constrained, with estimates that vary from as old ca. 13 Ma at its base to as young as ca. 100 ka at its highest levels. As part of geologic mapping program efforts, we are applying detrital sanidine Ar-Ar geochronology and detrital zircon U-Pb geochronology to more tighlty bound the depositional age and duration of these alluvial deposits and their context within the late Cenozoic paleo-landscape of the ancestral Pecos River.
A variety of geological studies involving Upper Paleozoic strata, conducted during the mid-twentieth century, produced a preliminary stratigraphic nomenclature for Carboniferous and Permian sedimentary rocks in New Mexico, and a general understanding of the lithostratigraphy, age and distribution of these rock units. Ongoing investigations by geologists from the NMBGMR, universities, museums, and industry are aimed at refining this understanding. For example, strata pertaining to the Pennsylvanian System are often poorly delineated and/or subdivided on geologic maps, due in large part to their lithostratigraphic complexity and a loosely defined stratigraphic nomenclature. Progress has been made during the past 15 years toward improving the stratigraphic nomenclature for Upper Paleozoic strata in New Mexico, and documenting stratigraphic patterns, both of which should provide a better foundation for ongoing and future studies of these rocks.
Geologists and hydrologists have been interested in basin-fill sediments of the Engle and Palomas Basins in Sierra County since the early 1900s. These Rio Grande rift basins contain packages of sediment shed from the surrounding uplifts over the last ~27,000,000 years. Well logs indicate that these basin-fill deposits, named the Santa Fe Group, are as much as 2 kilometers thick in places.
The Department of Energy has awarded New Mexico Tech a contract to examine rare earth elements (REE) and other critical minerals (CM) in coal and associated strata in the San Juan and Raton basins in northern New Mexico. Critical minerals are mineral resources that are essential to our economy and whose supply may be disrupted (/publications/periodicals/earthmatters/23/n1/em_v23_n1.pdf). Most CM are 100% imported into the U.S. Many CM are found in the San Juan and Raton basins of New Mexico.
