GEO-CM: Prospecting for critical element deposits: an interdisciplinary approach using experimental geochemistry and field-informed modeling of sediment transport

Critical minerals like cobalt, niobium, and tin are essential resources needed for modern technologies. These technologies include smartphones, batteries, electric vehicles, and satellites. Critical minerals are a key resource needed to move to a sustainable energy economy.

However, the demand for these minerals could soon exceed the available supply. Additionally, there is a risk of disruptions in the international supply chain. To lower these risks, which carry significant economic and national security implications, the goal of this proposal is to increase geoscientists' abilities to find more of these critical mineral resources in the Earth.

This project will create new tools to analyze river sediment with two main objectives. First, the work will determine whether critical minerals might be upstream that have not yet been discovered. Second, the project aims to locate places upstream where these minerals are concentrated.

This project will provide education and training on critical mineral research to a PhD student, a postdoc, and multiple undergraduate students. A critical mineral module will make up approximately 2-3 weeks of lectures for an undergraduate Earth Materials course. The PIs will also partner with a local youth leadership and workforce development program in Rochester, NY.

The goal of the partnership is to provide experience in environmental research and careers for students from underrepresented groups over the summer.

Imagine collecting a scoop of sand from a river; hidden in that single scoop lies information about the rocks in the entire drainage basin. Analysis of the sediment grains may reveal the presence of a critical element of interest in a proxy mineral, indicating a source rock of possible interest somewhere in the area. This project explores two questions: Does the trace element concentration within minerals in sediment fingerprint a potentially fertile igneous source enriched in the critical element of interest?

If it does, can the transport history of the sediment be modeled using physical properties of the grain such as shape and size to constrain the likely location of the fertile source that produced it? The goal of this work is to enhance prediction capabilities of undiscovered critical mineral-rich source rocks by using river sediments for prospecting by combining 1) high temperature laboratory experiments to characterize zircon, quartz, and rutile chemistry so that they can be used as “indicator minerals” for critical mineral deposits and 2) numerical modeling and field-based sediment tracer studies that will improve predictions of sediment transport distance and the location of viable critical mineral source rocks.

For the first objective, the team will use experimental geochemistry to synthesize quartz, zircon, and rutile in the presence of a critical element bearing mineral. These experiments will allow the researchers to define the threshold concentrations of different critical elements in target indicator minerals that would suggest a fertile source. For the second objective, the investigators will use coupled fluid-granular numerical models to develop new statistical distributions of sediment transport distance depending on grain shape and size.

The team will also use RFID-tagged rocks to track sediment transport in two natural rivers to determine how sediment size and shape affect their travel distances in natural systems. This fundamental work will set the stage for future development of a comprehensive model that predicts critical mineral source rock location from river sediment properties alone.

Findings from this proposal will extend beyond mineral prospecting; developing a new view of the processes that occur during the lifetime of sediments, from birth within a rock to transport and degradation through a river system, has implications for the fundamental understanding of Earth materials and the evolution of Earth’s surface.

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.