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Environmental predictors of deep-sea polymetallic nodule occurrence in the global ocean

Adriana Dutkiewicz, Alexander Judge and R. Dietmar Mueller
Environmental predictors of deep-sea polymetallic nodule occurrence in the global ocean
Geology (Boulder) (January 2020) 48 (3): 293-297

Abstract

Polymetallic nodules found on the abyssal plains of the oceans represent one of the slowest known geological processes, and are a source of critical and rare metals for frontier technologies. A quantitative assessment of their occurrence worldwide has been hampered by a research focus on the northeastern Pacific Ocean and the lack of a global open-access data set of nodules. We have compiled a global data set of >10,000 seabed nodule and control samples, and combine it with digital grids of key environmental parameters to generate a predictive machine-learning model of nodule occurrence. In order of decreasing parameter ranking, we find that nodules are associated with very low sedimentation rates (<0.5 cm/k.y.), moderately high oxygen values (150 and 210 mmol/m (super 3) ), lithologies of clay followed by calcareous ooze, low summer surface productivity (<300 mgC/m (super 2) /day), low benthic biomass concentration (<1 log mgC/m (super 2) ), water depths >4500 m, and low total organic carbon content (0.3-0.5 wt%). Competing hypotheses for nodule sustention and thus continued growth on the seafloor are the removal of sediment by bottom-water currents and biological activity. Using a high-resolution eddy-resolving ocean circulation model, we find that the bottom-current speeds over nodule fields are too low (<5 cm/s) to remove sediment, implicating the activity of epibenthic megafauna as the most likely mechanism. Our global nodule probability map combined with the assessment of a range of environmental drivers provides an improved basis for decision and policy making in the controversial area of deep-sea exploration.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 48
Serial Issue: 3
Title: Environmental predictors of deep-sea polymetallic nodule occurrence in the global ocean
Affiliation: University of Sydney, School of Geosciences, Sydney, N.S.W., Australia
Pages: 293-297
Published: 20200103
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 35
Accession Number: 2020-028632
Categories: OceanographyEconomic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202019
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