Scientists are using data from NASA’s Earth Surface Mineral Dust Source Investigation (EMIT) satellite to create detailed geologic maps of the McDermitt Caldera, a massive volcanic feature spanning parts of Oregon, Nevada, and Idaho. The work, focused on classifying up to 47 geologic units within the caldera, leverages imaging spectroscopy to analyze the chemical composition of bedrock, sediments, and soils.
The McDermitt Caldera, formed approximately 16.4 million years ago by the Yellowstone hotspot, is an oval-shaped depression measuring 28 miles north-south and 22 miles east-west. Located in southeastern Oregon and northern Nevada, the caldera’s highest point, Jordan Meadow Mountain, reaches 6,816 feet above sea level. Researchers are applying partial least squares discriminant analysis (PLSDA) models, trained using a pre-existing geologic map published in 2017, to the EMIT data.
The EMIT satellite, currently operating from the International Space Station, collects imaging spectroscopy data with a 60-meter pixel size. The underlying hypothesis driving the mapping effort is that the chemical signatures of sediments, soils, and plants are predictably linked to the bedrock below. This allows for geologic classification even in areas obscured by surface cover.
Initial validation results have shown varying degrees of success. Mapping of biotite rhyolite lavas and some basalts achieved up to 90% accuracy. But, classifying other units – including McDermitt tuff, anorthoclase-phyric rhyolite lavas, rhyolite of McDermitt Creek, and Quaternary deposits – proved more challenging. Researchers found that the chemical composition and heterogeneity of geologic units significantly impacted classification accuracy.
The research indicates that consolidating or un-consolidating geologic units can improve classification results in certain cases. For example, grouping basaltic lavas or separating Quaternary units increased accuracy. The caldera has a history of resource extraction, with mercury and uranium mined in the 20th century. Currently, exploration is underway for potential lithium deposits, beginning around 2017.
Prior to American settlement, the McDermitt Caldera region was inhabited by the Shoshone and Northern Paiute people. Today, the area remains ecologically critical, serving as a habitat for endangered species such as sage grouse and the Lahontan cutthroat trout. Further research is planned to refine the PLSDA models and improve the accuracy of geologic mapping across the caldera.
