Tectonic Evolution of the Ancestral Rocky Mountain System

The Ancestral Rocky Mountain (ARM) system extending from Utah to Oklahoma consists of eroded mountains and adjacent sedimentary basins that formed during a tectonic event occurring about 325 to 275 million years ago. Little is known about the structures (e.g., faults) responsible for the development of the ARM system. This research project will use a multidisciplinary approach to gain insight into the deformation associated with this tectonic event and with complex mountain belts more generally. This research may help recognize geological resources present across the region such as hydrocarbons and critical mineral deposits. The project will also train students in geologic mapping and structural geology research. Current knowledge of the geometry and kinematics of faults responsible for ARM uplift is extremely limited because most of its structures are either not exposed or have been overprinted by Late Cretaceous-early Paleogene (Laramide) deformation. More outcrop-based structural data and new constraints on the timing of structures are needed. The researchers will study four field areas in southern and central Colorado along the margins of the Ancestral Uncompahgre uplift that clearly preserve late Paleozoic (Pennsylvanian-Permian) structures. These field areas offer a unique opportunity to investigate ARM deformation. The researchers will document in detail the geometry, kinematics, and field relations associated with faults and growth folds in these regions. They will also map key portions of the fault systems to evaluate relative timing relations and how ARM deformation was influenced by basement structures. The ages of dozens of structures will be determined using Uranium-Lead geochronology on calcite that formed in fractures during deformation. ARM layer-parallel shortening directions in Pennsylvanian-Permian strata will also be evaluated using anisotropy of magnetic susceptibility. This research will provide new insights into Laramide strain directions recorded in Mesozoic strata. It will also shed light on why ARM structures were or were not reactivated during Laramide compression. The research will test kinematic models that are based largely on subsurface data, providing a new structural framework for the ARM system. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2523863 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: John Singleton | Institution: Colorado State University, FORT COLLINS, CO | Award Amount: $299,919 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2523863 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2523863.html