One primary area of interest for researchers on the Escanaba Trough expedition is to expand knowledge of the mineral resources found at seafloor spreading centers such as Escanaba Trough. Among these seafloor resources are potential deposits of minerals, deemed “critical” to national security and commerce, which have supply chains vulnerable to disruption.
Deep Dive: Critical Mineral Resources in Escanaba Trough
Critical minerals are essential to the production of high-tech equipment in a wide variety of sectors including energy production, national defense, battery technology, information technology, and health care. Large quantities of critical minerals such as nickel, cobalt, and rare earth elements are fundamental components needed for a transition to renewable energy sources. Identifying domestic sources of these critical minerals contributes to strengthening supply chains and represents a potential revenue source for the U.S.
Escanaba Trough is the only seafloor spreading center within the U.S. Exclusive Economic Zone (EEZ). EEZs extend 200 nautical miles from the shores of coastal nations, granting them control of energy or mineral resources located therein, from surface waters to the seafloor. The U.S EEZ, at 4.4 million square miles, is larger than the country’s entire land area.
At seafloor spreading areas such as the Escanaba Trough, which is part of the larger Gorda Ridge system, diverging tectonic plates allow heat from the earth’s mantle to interact with seawater, creating hydrothermal fluids rich with minerals. As these fluids heat up and rise back to the seafloor surface, they are cooled by seawater, forming mineral deposits known as seafloor massive sulfides. At Escanaba Trough, thick layers of sediment—up to 500 meters deep in places—serve to trap heat emitted by the tectonic boundary, allowing elements and minerals to gradually precipitate near active heat sources. While most of the hydrothermal systems at Escanaba Trough are no longer active, the mineral deposits they left behind are largely unexplored and poorly understood.
Of particular interest to the Global Marine Mineral Resources group is how hydrothermal systems change over time. Because most of the hydrothermal activity at Escanaba Trough either ceased long ago or is gradually cooling down, researchers want to know how mineral deposits there may be altered over time as they interact with seawater and move further from active heat sources.
Previous studies of this area suggest that large quantities of sulfide minerals may be present in the sediments at Escanaba Trough. The Bureau of Ocean Energy Management (BOEM) and USGS work together to identify the location and extent of mineral resources within the EEZ, as well as to better understand the biology and ecology of the deep-sea environments where they are located. This combined inventory provides valuable information to ensure responsible stewardship over the submerged lands of the U.S.
USGS partners with BOEM to characterize the U.S. EEZ with modern remote sensing systems to find areas favorable for critical minerals. The inventory of hard mineral resources will include identification of offshore areas where these minerals are likely to occur. These areas can be further characterized to help understand the broader environment, including the roles that these minerals play as part of the habitat and ecology of the deep sea.
Watch three short videos about this expedition, read other deep-dive stories to learn more about the hydrothermal systems and marine geology of Escanaba Trough, and read about why the USGS goes to such depths.