Collaborative Research: GEO-CM Critical Mineral Provenance of Southeastern U.S. Clastic Systems - Focus on Detrital Monazite

Syracuse University, Syracuse NY

Investigators

Abstract

The U.S. lacks resources for many minerals that contain elements critical to the national economy and to national security. This project will explore new sources of the chemical elements called the “rare earth elements” (REEs). These are metallic elements with strong magnetic properties and are critical to the energy transition. There is only one currently producing domestic U.S. source of REE. The majority of world production of REEs is from a single mine in China. The proposed research will explore for REE mineral deposits in bedrock, stream sediments, and sedimentary rocks in the Piedmont and Coastal Plain provinces. The mineral monazite is the most common REE-bearing mineral in the crust. Preliminary research demonstrated that monazite is widespread in the region. This new project will address the following questions. (1) What is the source of the monazite currently transported by rivers from the Appalachian Mountains to the Atlantic coast? (2) Is the source metamorphic rocks or igneous rocks, or both? (3) Has the source changed over geologic time? (4) What are the best methods for locating these deposits? Methods used to answer the questions include mass spectrometry and scanning electron microscopy. The answers will permit mineral exploration companies to focus exploration and development on the highest-grade source regions. The project will train graduate and undergraduate students at the University of Kentucky and Syracuse University. Upon graduation these students will be prepared to join the workforce in critical mineral exploration. The project will involve a high school earth science teacher to create science education content. The research will improve the ability of the U.S. to address the critical mineral needs outlined in Executive Orders 13953 and 14017. Research will test hypotheses for the provenance of detrital monazite in clastic systems in the Atlantic Coastal Plain that were demonstrated by the USGS to be critical REE placer mineral deposits. The research addresses the GEO-CM charge of research “leading to advanced understanding of geologic and geochemical processes through which critical minerals form and are concentrated into economically viable deposits”. The Atlantic Coastal Plain province has proven REE potential based on detrital monazite in Upper Cretaceous to modern clastic systems between the Fall Line and the Atlantic littoral zone. The long-hypothesized source of monazite in these deposits are belts of middle to late Paleozoic medium- to high-grade metapelites and granitic magmatic rocks in the crystalline Piedmont and Blue Ridge Provinces. Rather than using detrital zircon as a proxy for the heavy mineral suite, the researchers will date the ore mineral of interest (monazite) for testing provenance models. High-throughput monazite laser ablation-split stream-inductively coupled plasma-mass spectrometry (LASS-ICP-MS) will be used to obtain U-Pb dates and REE concentrations. They will conduct a geochronologic survey of monazite in potential bedrock metamorphic and magmatic sources, not already characterized by their prior research, which will be used to assess provenance and sediment delivery paths from inferred Appalachian sources to Coastal Plain clastic systems. In addition to monazite age and REE variations, the researchers will measure Nd isotope compositions in detrital monazite and source rocks as additional tests of provenance. Samples will include crystalline bedrock (metamorphic and granitic units), modern sediment in headwater streams and trunk streams flowing to the coast (e.g., the Broad River drainage basin), and Upper Cretaceous to Lower Tertiary coastal plain sediments at the Fall Line that are exceptionally high in detrital monazite. The project will train graduate and undergraduate students at the University of Kentucky and Syracuse University. Upon graduation these students will be prepared to join the workforce in critical mineral exploration. The project will involve a high school earth science teacher to create science education content. The research will improve the ability of the U.S. to address the critical mineral needs outlined in Executive Orders 13953 and 14017. 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.