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Unusual Mineral Deposits Record the Unique History of the Arctic Ocean



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Little is known about marine mineral deposits in the Arctic Ocean, an ocean dominated by shallow areas of continental shelf and deep basins with limited circulation. USGS scientists and their colleagues have published the first comprehensive paper on this subject, “Deep water ferromanganese-oxide deposits reflect the unique characteristics of the Arctic Ocean,” in the American Geophysical Union (AGU) journal Geochemistry, Geophysics, Geosystems (G-cubed).

Bathymetry of the Arctic Ocean, with black rectangle delineating the study area
Above: Bathymetry of the Arctic Ocean, with black rectangle delineating the study area. White star marks site where sample in photograph was collected. Its cut surfaces show layers in Fe-Mn crust. Each square in scale beneath sample is 1 centimeter (cm). Base map from International bathymetric chart of the Arctic Ocean (IBCAO). Photo by James Hein, USGS [larger version]

Eleven coauthors contributed to this interdisciplinary study of ferromanganese (Fe-Mn) deposits from the Amerasia Basin in the Arctic Ocean. Their paper integrates geology, geochemistry, oceanography, seawater chemistry, regional tectonics, history of the Arctic, and more.

The authors analyzed Fe-Mn crusts and nodules collected in 2008, 2009, and 2012, and found them unusually enriched in the rare metal scandium. The researchers also analyzed water-column samples collected in 2015, focusing on scandium in both particulate and dissolved form. The Arctic Fe-Mn crusts and nodules are the only ones in the global ocean highly enriched in this rare metal, for which there is no land-based mine. Scandium is in great demand to amalgamate with aluminum to make light, fuel-efficient aircraft.

The Arctic Fe-Mn crusts have many unique characteristics besides high scandium, all unlike any other crusts found elsewhere, and those characteristics reflect the history of the Arctic Ocean. For example, the Arctic crusts have unique mineral and chemical compositions compared with deposits found elsewhere: atypically high growth rates, high detrital contents, high Fe/Mn ratios, and low silicon/aluminum (Si/Al) ratios. High detritus reflects erosion of underwater outcrops and onshore rocks in North America and Siberia, transport by rivers and glaciers to the sea, and distribution by sea ice, brines, and currents. High Fe/Mn ratios are attributed to the Arctic Ocean’s broad continental shelves, where chemical reactions release Fe to bottom waters that flow to the deeper basins.

Analyses of crust growth layers that accreted over the past 15 million years revealed changes in the crusts over time, such as a decrease in scandium concentration. The changes indicate that the Arctic crusts are becoming more like crusts from elsewhere in the global ocean as the Fe/Mn ratio and amount of detritus decrease.

To learn more, read the new paper, “Arctic Deep Water Ferromanganese-Oxide Deposits Reflect the Unique Characteristics of the Arctic Ocean.”

The full citation is:
Hein, J.R., Konstantinova, N., Mikesell, M., Mizell, K., Fitzsimmons, J.N., Lam, P., Jensen, L.T., Xiang, Y., Gartman, A., Cherkashov, G., Hutchinson, D.R., and Till, C.P., 2017, Arctic deep water ferromanganese-oxide deposits reflect the unique characteristics of the Arctic Ocean: Geochemistry, Geophysics, Geosystems, https://doi.org/10.1002/2017GC007186.

Related Sound Waves Stories
James Hein Wins Prestigious Moore Medal Award from the International Marine Minerals Society
Oct. - Dec. 2016
Jim Hein Receives Distinguished Service Award—U.S. Department of the Interior’s Highest Honor
March–June 2015 Double Issue
South Korean Geoscientists Visit the USGS in Menlo Park and Santa Cruz, California
Jan. / Feb. 2013

Related Websites
Pacific EEZ Minerals
USGS
International Marine Minerals Society
IMMS

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Cover Story
Evolution of a Hurricane-Generated Breach

News Briefs
News Briefs

Research
Annual Southern Sea Otter Survey

Three New Studies added to USGS Oceanographic Time-Series Data Collection

Field Work
Recent Fieldwork

Outreach
Graduate Students View Evidence of Carmel River Recovery after Dam Removal

Woods Hole Coastal and Marine Science Center Outreach

Meetings
SACNAS Conference

Publications
Ferromanganese Deposits Record History of the Arctic Ocean

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