Marine Mineral Resources and Law of the Sea -1 | Geology Optional for UPSC PDF Download

Marine Mineral Resources

Marine mineral resources refer to mineral accumulations that develop on or below the seafloor, from which metals, minerals, elements, or aggregates can be extracted as valuable resources.

Types of Marine Mineral Resources

• Manganese Nodules: Found at depths of less than 4000 meters.
• Gas Hydrates: Located between 350 and 5000 meters below the sea surface.
• Cobalt Crusts: Form along the flanks of undersea mountain ranges at depths ranging from 1000 to 3000 meters.
• Massive Sulfides and Sulfide Muds: Develop in areas of volcanic activity near plate boundaries, typically at depths of 500 to 4000 meters.

Utilization of Marine Mineral Resources

• Historical Exploitation: The seafloor has been exploited historically for resources such as sand, gravel, oil, and gas.

Mineral Recovery from the Seabed

Overview

• Advancements in mineral recovery and exploration of new marine mineral sources have progressed rapidly in recent years.
• Offers significant economic benefits and potential valuable additions to the global resource supply.

Types of Marine Minerals

• Commercial exploitation focuses primarily on solid marine minerals originating from the mechanical and chemical erosion of continental rocks.
• These minerals are transported to the ocean by rivers and are typically found in shallow offshore regions within the territorial sea and exclusive economic zone (up to 200 nautical miles).

Placer Deposits

• Minerals resulting from the mechanical erosion of continental rocks are concentrated in placer deposits.
• These deposits are sorted by water movement based on the varying density of constituent minerals.

Examples include:

• Heavy metallic elements: Gold, iron, rare earth elements
• Nonmetals: Diamonds, siliceous sand

Manganese Nodules

• Size: Range from a potato to a head of lettuce.
• Composition: Primarily manganese, iron, silicates, and hydroxides.
• Growth Rate: 1 to 3 millimeters per million years.
• Formation: Precipitation of chemical elements from seawater or pore waters in underlying sediments.

The Formation of Cobalt-Rich Ferromanganese Crusts

Characteristics

• Metallic mineral resources containing metals sourced from both land and sea origins.
• Thin layers, up to 25 centimeters thick, on volcanic rocks.
• Found on seamounts and submerged volcanic mountain ranges at depths of 400 to 4000 meters.

Locations

• Most concentrated deposits are within the exclusive economic zones of western Pacific island nations.
• Potential: A single mining site could contribute up to 25% of the global cobalt demand annually, subject to technological advancements.

Formation Process

• Incorporation of metals from land and sea sources.
• Elements like manganese, iron, cobalt, copper, nickel, and platinum precipitate from seawater onto volcanic substrates.

Polymetallic Massive Sulfides Formation

Formation Process

• Created by magma upwelling beneath submerged volcanic mountain ranges.
• Seafloor hot springs (black smokers) form when magma heats the seafloor.
• Metals dissolved in rocks are carried by hydrothermal solutions to form polymetallic massive sulfides.

Discovery

• First identified in oceanic environments in 1979.
• Previously known from land deposits mined for metals such as copper, iron, zinc, silver, and gold.

Formation of Mineral Deposits in Marine Environments

Seafloor Hot Springs and Massive Sulfides

• Massive sulfides form around seafloor hot springs (e.g., black smokers) deriving heat from magma beneath submerged volcanic ranges.

Seafloor Spreading

• Magma cools and solidifies during seafloor spreading, creating fresh seafloor segments.

Formation of Limestones

• Limestones form abundantly in tropical and semi-tropical oceans due to precipitation by biological organisms such as mollusks, corals, and plants.

Magnesium Extraction from Seawater

• Magnesium is the only metal extracted from seawater.
• Concentration: Approximately 1000 ppm in a dissolved state.

Phosphate-Rich Crust Formation

• In shallow marine environments, complex organic and inorganic processes result in the precipitation of phosphate-rich crust and granules.