The Front Range of the Southern Rocky Mountains near Boulder, CO contains a rock record that spans nearly 1.7 billion years. Zircon U-Pb geochronology is an isotopically-based chronometer for measuring deep earth time. We apply this method to a series of small igneous intrusive bodies from the Front Range west of Boulder, CO. These instrusives are collectively known as the Colorado Mineral Belt (CMB) for the economic mineral deposits associated with the instrusives. Past geochronological methods have provided only rudimentary constraints on the geologic timing of emplacement of these bodies. We demonstrate the CMB magmatic activity in the Front Range occurred in two discrete pulses, one at ~67 Ma (million years ago) and one at ~47 Ma. Additional application of the same methodology to a sedimentary rock, the Neoproterozoic Tavakiav Quartzite, uses the zircon U-Pb ages as tracers to constrain the provenance and depositional age of this unique sand body.
Murray, K. E., Niemi, N. A., & Clark, M. K. (2025). Evidence for the Neoproterozoic rifting of Rodinia in the Rocky Mountain Front Range. Tectonics, 44, e2023TC008216.
These data were produced in the scope of research into understanding the application of zircon (U-Th)/He thermochronometric data derived from rocks with complex radiation damage distributions to the extraction of long-term (>1 Gyr) thermal histories of the Earth's upper crust. The samples used in this study were collected from the Front Range in Colorado, USA. The low-temperature (apatite and zircon (U-Th)/He) thermochronometric ages presented in this data set are sensitive to near-surface temperatures (~80C and 180C, respectively) and record the progressive exhumation of the rock mass from which the samples were collected towards the Earth's surface. These thermochronometric ages, and the differences between them, provide insight into the deep-time (~1000 Ma - 100 Ma) thermal history of the Colorado Front Range.
