Prospective regions for marine minerals on the Alaska Outer Continental Shelf

Global and regional oceanographic and geologic spatial datasets were compiled and visually overlaid to determine regions meeting all the known criteria for ferromanganese crust formation (hard rock substrate on seamounts, low sedimentation rate), and abyssal manganese nodule formation (flat and sediment-covered basins, low sedimentation rate, low to moderate primary productivity, depths below the carbonate compensation depth, seafloor lithology), and hydrothermal minerals (along active arc, including extensional regions).

Marine geologic samples were compiled within the following four deep ocean areas of interest surrounding Alaska: Gulf of Alaska Seamounts, Aleutian Arc, Canada Basin, and Chukchi Borderland.

Areas were outlined to create a set of prospective regions for the marine mineral type predicted to occur in each of the Alaska deep ocean regions: ferromanganese crusts in the Gulf of Alaska Seamounts and Chukchi Borderland, manganese nodules in Canada Basin, and hydrothermal minerals in the Aleutian Arc. Areas were outlined that met all the formation criteria for each mineral type and were refined based on where samples were collected that confirmed the presence of marine minerals as well as specific criteria in each region as follows: 1) in the Gulf of Alaska Seamounts, areas prospective for ferromanganese crusts are at water depths shallower than 3,000 meters (m) (or 2,850 m where the abyssal plain doesn't reach 3,000 m); below 3,000 m, thick ferromanganese crusts are less likely to occur due to higher sedimentation rates and distance from oxygen minimum zones (OMZ) that are a reservoir of dissolved manganese; 2) for Chukchi Borderland, regions prospective for ferromanganese crusts are between water depths of 300 and 2,800 meters (m), except on the eastern flank of the Northwind Ridge where prospective depths extend down to 3,800 m, owing to steep slopes that prevent sediment accumulation; 3) for manganese nodules in the Gulf of Alaska, areas prospective for manganese nodules are at water depths of 3,800 m or deeper, where the Canada Basin Abyssal Plain is deepest, flattest, and undergoes the lowest sedimentation rates; 4) for the Aleutian Arc, the arc is prospective for hydrothermal minerals, specifically potential extensional regions. Prospective regions were converted to shapefiles in ArcGIS software for each mineral type for use in GIS applications such as maps, modeling, or other.