UPSC MainsGEOLOGY-PAPER-II20245 Marks
Q25.

What are the different marine mineral resources?

How to Approach

This question requires a descriptive answer outlining the various mineral resources available in the marine environment. The answer should categorize these resources based on their occurrence (e.g., seafloor, sediments, brines) and composition (e.g., polymetallic nodules, sulphides, crusts). Mentioning the geological processes involved in their formation and potential economic significance is crucial. A structured approach, categorizing resources and providing examples, will be effective.

Model Answer

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Introduction

Marine mineral resources represent a significant, largely untapped potential for future economic development. These resources, found on the seafloor and within marine sediments and brines, are formed through various geological processes, including hydrothermal activity, volcanic eruptions, and biogenic accumulation. With increasing demand for metals and minerals, and dwindling land-based reserves, exploration and sustainable exploitation of marine mineral resources are gaining prominence. The United Nations Convention on the Law of the Sea (UNCLOS), 1982, provides the legal framework for regulating activities related to these resources in international waters.

Types of Marine Mineral Resources

Marine mineral resources can be broadly classified into several categories based on their geological origin and composition:

1. Polymetallic Nodules

  • Description: These are potato-sized concretions found on the abyssal plains, typically at depths of 4,000-6,000 meters. They consist of manganese, iron, nickel, copper, and cobalt.
  • Formation: Their formation is complex, involving precipitation of metals from seawater around a nucleus (e.g., a fish tooth or clay particle).
  • Occurrence: Clarion-Clipperton Zone (Central Pacific Ocean) is the most prominent area.
  • Economic Significance: Important source of nickel, cobalt, and rare earth elements crucial for battery technology.

2. Polymetallic Sulphides

  • Description: Formed by the precipitation of metal sulphides around hydrothermal vents (black smokers) along mid-ocean ridges and volcanic arcs. They are rich in copper, zinc, lead, gold, and silver.
  • Formation: Hot, chemically-rich fluids from the Earth's interior react with cold seawater, causing metals to precipitate.
  • Occurrence: Red Sea, East Pacific Rise, Juan de Fuca Ridge.
  • Economic Significance: High concentrations of valuable metals make them economically attractive, but extraction is technically challenging.

3. Cobalt-Rich Crusts

  • Description: Ferromanganese crusts found on seamounts and plateaus, enriched in cobalt, nickel, platinum, and other rare metals.
  • Formation: Slow precipitation of metals from seawater over millions of years.
  • Occurrence: Western Pacific Ocean (e.g., Emperor Seamounts), Indian Ocean.
  • Economic Significance: Cobalt is vital for lithium-ion batteries and superalloys.

4. Phosphorites

  • Description: Sedimentary deposits rich in phosphate minerals, used in the production of fertilizers.
  • Formation: Accumulation of phosphate derived from the weathering of rocks and biological processes.
  • Occurrence: Continental shelves and upwelling zones (e.g., off the coast of Peru and Namibia).
  • Economic Significance: Essential for agriculture and food security.

5. Marine Placers

  • Description: Accumulations of heavy minerals (e.g., gold, tin, ilmenite, zircon) concentrated by wave and current action.
  • Formation: Erosion of land-based sources and subsequent concentration by marine processes.
  • Occurrence: Coastal areas and continental shelves.
  • Economic Significance: Historically important source of tin and gold.

6. Dissolved Minerals in Seawater

  • Description: Seawater contains dissolved salts and minerals, including magnesium, bromine, potassium, and uranium.
  • Formation: Leaching of minerals from rocks and volcanic activity.
  • Occurrence: Globally distributed.
  • Economic Significance: Magnesium is used in alloys, bromine in flame retardants, and uranium in nuclear power. Extraction is energy-intensive.

7. Gas Hydrates

  • Description: Ice-like crystalline solids containing methane trapped within a water lattice.
  • Formation: Formed under high pressure and low temperature conditions, typically in deep-sea sediments and permafrost regions.
  • Occurrence: Continental margins worldwide.
  • Economic Significance: Potential future energy source, but extraction is technically challenging and environmentally sensitive.

Technological Challenges: Extracting these resources presents significant technological hurdles, including deep-sea mining techniques, environmental impact assessment, and ensuring sustainable practices.

Conclusion

Marine mineral resources hold immense potential to address future resource demands, but their exploitation requires careful consideration of environmental impacts and adherence to international regulations like UNCLOS. Sustainable exploration and responsible mining practices are crucial to minimize ecological damage and ensure long-term benefits. Further research and technological advancements are needed to overcome the challenges associated with deep-sea mining and unlock the full potential of these valuable resources.

Answer Length

This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.

Additional Resources

Key Definitions

Hydrothermal Vents
Fissures on the seafloor that release geothermally heated water. These vents are often associated with volcanic activity and are rich in dissolved minerals.
Abyssal Plain
A flat, sediment-covered area of the deep ocean floor, typically found at depths greater than 3,000 meters.

Key Statistics

Estimated global reserves of polymetallic nodules are in the range of 5-10 billion tonnes, containing significant amounts of nickel, copper, cobalt, and manganese.

Source: International Seabed Authority (ISA) - as of 2023 knowledge cutoff

The estimated amount of dissolved magnesium in seawater is approximately 1.3 x 10^15 tonnes (as of 2023 knowledge cutoff).

Source: US Geological Survey

Examples

Deep Sea Mining in the Clarion-Clipperton Zone

The Clarion-Clipperton Zone in the Pacific Ocean is a prime target for polymetallic nodule mining. Several companies have been granted exploration licenses by the ISA, but commercial mining has not yet commenced due to environmental concerns and regulatory uncertainties.

Frequently Asked Questions

What are the environmental concerns associated with deep-sea mining?

Deep-sea mining can disrupt fragile ecosystems, create sediment plumes that smother marine life, and release toxic metals into the water column. It also poses a threat to biodiversity and potentially impacts carbon sequestration processes.

Topics Covered

GeologyEconomic GeologyOceanographySeabed MiningMarine DepositsPolymetallic NodulesManganese Crusts