Postdoctoral Fellowship: EAR-PF: Quantifying the Paleolatitude of a Continental Ice Sheet

Paleomagnetic data are the primary way geologists develop maps to understand the position of continents in geologic time. These maps of the ancient Earth are used by many fields of geology, including in the mining industry to look for new mineral deposits. However, there are hundreds of millions of years that have limited to no paleomagnetic data. One such period corresponds to a time when glaciers have been thought to encase the planet in a ‘Snowball Earth’. The absence of paleomagnetic data from this time is due to the global lack of rocks in this age range. This postdoctoral fellowship research will support collection and paleomagnetic analysis of rare rock samples to establish the latitude that ice sheets reached on land during the Snowball Earth glaciation. This project supports the national interest through improving understanding of potential locations for mineral deposits and building the STEM workforce through training and teaching of undergraduate researchers. One major question in Earth Science is whether the Earth was fully encased in ice during the two Snowball Earth intervals spanning the period from 717 to 635 Ma (Cryogenian Period). The extent of icesheets on land can be directly established if paleomagnetic data could be developed from Cryogenian-aged rocks, but deposits of this age are exceedingly rare and globally define the ‘Great Unconformity’. Furthermore, there are an increasing number of critical mineral deposits found in association with the Great Unconformity and plate reconstructions are central to understand how these deposits formed. A promising target to help fill in this critical interval with paleomagnetic data are the ca. 690 to 660 Ma Tavakivi sandstone injectites (Tava) from the Front Range of central Colorado. These rocks have recently been dated by hematite uranium-lead (U-Pb) geochronology. This NSF Earth Science Postdoctoral Fellowship seeks to develop a high temporal resolution record of Laurentia’s paleolatitude approximately 690 to 660 million years ago by developing paleomagnetic and geochronologic data on the Tava injectites. Results from this project will have implications for the broader Earth Sciences community and contribute to the development of the United States’ STEM workforce through the teaching and mentorship of undergraduates in understanding critical mineral deposit development associated with the Great Unconformity. 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.