Collaborative Research: Reconstructing the Missing Record of late Proterozoic Tectonism along the Western Margin of Laurentia using Deep-Time Thermochronology

Lead PI: Dr. Stephen Ellis Cox , Murray, Kendra E.; Pearson, David; Orme, Devon E

Unit Affiliation: Geochemistry, Lamont-Doherty Earth Observatory (LDEO)

May 2022 - April 2025
North America ; United States
Project Type: Research

DESCRIPTION: Studies of sedimentary rocks provide geoscientists a record of Earth's history, including the appearance and evolution of life, the growth and demise of mountains, and how the climate has changed. However, natural processes driven by plate tectonics mean that this sedimentary record is inherently incomplete. At different times during Earth?s history, some regions experienced sediment deposition, which buries and therefore heats up rocks, while other regions experienced erosion, which both removes portions of the rock record and cools off the rocks that persist by bringing them closer to Earths's surface. This study will use the geochemical signatures of rock heating and cooling that occurs during deposition and erosion to understand the geologic histories of areas where no sedimentary rocks remain. Specifically, the study will investigate the ancient record of supercontinent breakup, a process that drives changes in sea level, global climate, and topography. This project will provide support for three early-career researchers at different universities, including two women, and build new relationships among the collaborating research groups. Three graduate and nine undergraduate students from different universities will be engaged in collaborative, hypothesis-driven research and learn a range of field, laboratory, and science communication methods. The researchers will also collaborate with the Idaho Museum of Natural History to create a mobile museum exhibit that will highlight the ancient history of the charismatic mountain ranges in the study area and visit museums that serve rural communities in the Rocky Mountains.

Unconformities, which are abundant in the rock record, are traditionally viewed as unfillable gaps in the rock record of Earth?s history. However, the thermal imprint of sedimentary cover on the basement rocks that underlie many unconformities provides a rich archive of the otherwise inaccessible parts of a continent?s tectonic history. This record is now accessible due to recent conceptual and analytical advances in low-temperature thermochronology. The primary objective of this study is to contribute to these advances by targeting a critical gap in knowledge about Laurentian tectonics, the breakup of supercontinent Rodinia, while establishing an approach to deep-time thermochronology that can document Precambrian tectonic activity in regions that also experienced significant Phanerozoic mountain building. This study will sample along a 700-kilometer-long segment of western Laurentia?s rifted margin, targeting basement rocks directly below the Great Unconformity and using four chronometers to produce holistic tectonothermal histories to fill a billion-year gap in the rock record. This study will demonstrate how deep time thermochronology can provide a new perspective on the geometry and tectonic evolution of western Laurentia's rifted margin, where much or all of the sedimentary record of Neoproterozoic tectonism is missing. This capability will be tested by (1) establishing a clear link between extant Neoproterozoic sedimentary rocks and Neoproterozoic tectonothermal events in the Uinta Mountains, (2) documenting the Proterozoic thermal histories of basement blocks with no overlying Neoproterozoic strata in the Teton Range and southwestern Montana, and (3) quantifying intra-mountain range variability of Proterozoic thermal histories to evaluate the sampling spatial resolution necessary for extracting meaningful tectonic information from the deep-time thermochronologic record.

BROADER IMPACTS: This project will provide support for three early-career researchers at different institutions, including two women, and build new relationships among PIs and collaborating labs. We will engage 3 graduate and 9 undergraduate students from different universities in hypothesis-driven research, provide mentoring and collaboration opportunities for these students, and facilitate them working together to learn a range of field, lab, and science communication methods. Research results will be broadly disseminated through publications, presentations, and data repositories. Two of our institutions are in states (Idaho and Montana) traditionally underfunded in scientific research and infrastructure. The public-facing product of this project will be a mobile museum exhibit entitled Mountains Through Time, which will be built in collaboration with the Idaho Museum of Natural History and highlight the deep-time history of the charismatic mountain ranges in our study area. This exhibit will directly appeal to G5-8 science standards and visit museums that serve rural communities in the Intermountain West.


National Science Foundation




Idaho State University, Montana State University