T1 Linking Mineral Resources and Their Geologic Framework I: The USGS Earth Mapping Resources Initiative (Earth MRI) and Related Critical Minerals Research

Sunday, 22 September 2024
8:00 AM - 12:00 PM
212A

I'VE GOT CONDUCTIVITY IN LOW-GRADE PLACES: AIRBORNE ELECTROMAGNETIC SURVEY REVEALS HYDROTHERMAL AND TECTONIC STRUCTURE AND POTENTIAL GRAPHITE IN THE SEWARD PENINSULA, ALASKA

Paper number: T1-4
Program: Technical Sessions
Time: 8:40 AM – 8:55 AM

Authors

Abstract

Crystalline graphite is a critical mineral used in modern batteries and essential for reaching sustainability goals for the energy storage and transportation sectors. However, the United States is currently completely reliant on foreign supply. The mountain ranges of the Seward Peninsula in Alaska contain several carbonaceous high-grade metamorphic units potentially permissive for graphite mineralization, including one known deposit at Graphite Creek in the northern Kigluaik Mountains. To aid in graphite assessment efforts and illuminating the complex geologic structures of the region, the U.S. Geological Survey and the Alaska Division of Geological and Geophysical Surveys conducted an airborne electromagnetic survey in 2023 and 2024 in the Seward Peninsula. This survey covered the Kigluaik, Bendeleben, and Darby Mountain Ranges, and included high-resolution coverage of the Pilgrim Creek Hot Springs Area. Preliminary resistivity models derived from the survey show elevated conductivity in areas of known graphite mineralization in granulite-facies metamorphic rocks in the central and northern Kigluaik mountains, with the highest conductivity beginning at about 20 m depth. Intriguingly, elevated conductivity is also present in the lower grade metamorphic rocks of the Nome Complex along the southern edge of the Kigluaiks. Preliminary models also reveal a zone of higher conductivity underlying the Pilgrim Hot Springs area; combined with modeling from an earlier and shallower electromagnetic survey, these resistivity models delineate the shallow and deep structure underlying the hydrothermal system. Final processing and analysis of these data are ongoing, with the potential to reveal greater insights into regional hydrothermal and tectonic structure relevant to graphite formation.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-402031

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