Minerals on Ocean Floor

  Aug 05, 2020

Minerals on Ocean Floor

aWhat is nature and extent of minerals on sea floor?

The vast repository of minerals, including the precious cobalt, zinc, manganese and rare earth materials are present in three forms of ore

  1. Polymetallic manganese nodules that remain strewn across the ocean floor;
  2. Cobalt-rich ferromanganese crusts that cover the seamounts; 
  3. Massive polymetallic sulfide (PMS) deposits around hydrothermal vents. 

PMS, containing iron, copper, zinc, silver, gold, platinum in variable constitutions, are precipitates of hot fluids from upwelling hot magma from deep interior of the oceanic crust, discharged through mineralized chimneys. PMS in the Ocean Ridges have attracted worldwide attention for their long-term commercial as well as strategic values.

What is a hydrothermal vent?

Hydrothermal vent is an underwater geothermal geyser. These vents are cracks in volcanic areas of the ocean floor through which seeps iron- and Sulphur-rich magma. As these minerals meet cold bottom water, they precipitate, creating high-grade deposits. Typically, an ore from seabed deposit is seven times enriched with minerals than that mined from land. This attracts governments who are fast running out of reserves on land.

There are two different types of hydrothermal vents; Black Smokers, and White Smokers. The black smoker is the hottest of all the hydrothermal vents. It spews out mainly sulfides and iron. When the warm water hits the cool water the minerals precipitate and it creates the black smoke effect. 

The white smoker typically has cooler water than that of the black smoker and is generally smaller in size as well. The minerals in the white smokers are barium, calcium, and silicon, which are white.

Hydrothermal vents are found on tectonic plate boundaries, most commonly mid-ocean ridges. Mid-ocean ridges are areas were two tectonic plates are moving away from each other and new crust is being formed. Magma is exposed to the sea water and is cooled which created the new crust. They can also be found in Subduction zones and hot spots. 

What is strategic importance of minerals on sea floor?

  1. Rare earth materials that are needed for smart phones, laptops, batteries and hybrid cars found in abundant quantity.
  2. As the world moves from fossil fuels to technologies like electric cars, some of the key elements—nickel and cobalt in particular—are more common on the seafloor than the land.
  3. Green energy wind turbines use strong magnets made from rare metals found in abundance in the lowest layer of the sea.
  4. China supplies more than 90 of the world’s market with its rare earth resources, which has strategic implications for India and the world.

What are rare earth metals and their significance?

The rare earth elements (REE) are a set of seventeen metallic elements. These include the fifteen lanthanides on the periodic table plus scandium and yttrium.

Rare earth elements are an essential part of many high-tech devices. Rare-earth elements (REE) are necessary components of more than 200 products across a wide range of applications, especially high-tech consumer products, such as cellular telephones, computer hard drives, electric and hybrid vehicles, and flat-screen monitors and televisions. 

Significant defense applications include electronic displays, guidance systems, lasers, and radar and sonar systems. Although the amount of REE used in a product may not be a significant part of that product by weight, value, or volume, the REE can be necessary for the device to function.

What is significance of life on sea floor for human beings?

These animals and microbes have evolved under an amazing array of extreme conditions, so there are all sorts of problems these organisms could help humans solve. These life forms could offer almost endless benefits. New medicines, antibiotics, anti-inflammatories, bio-materials, bio-inspiration. Researchers across world view the ocean as an amazing pot of genetic resources.

What is ISA and its role?

The International Seabed Authority is an autonomous international body that deals with the organizing, regulating and controlling of all mineral-related activities in the international seabed area beyond the limits of national jurisdiction. It was formed in 1994 under the United Nations Convention on the Law of the Sea (1982). India is party to ISA.

An important function of the authority is the regulation of deep seabed mining, protection of the marine environment from the harmful effects of mining, exploration and exploitation. The authority also promotes marine scientific research.

What are negative impacts of sea floor mining?

SFM can have negative impact on environment. Pollution and dust plumes caused by mining can harm bottom dwelling life. Their habitat may get destroyed due to machinery. Also, machinery may cause collapse of vent or under water landslide.

What activities are taken by India to explore these sea floor minerals?

Ministry of Earth Sciences (MoES), Government of India, signed a 15-year contract with the International Seabed Authority (ISA), for exploration of Poly-Metallic Sulfides (PMS) in Indian Ocean in 2016.

Samudrayaan project

The project proposes to send a submersible vehicle with three persons to a depth of about 6000 meters to carry out deep underwater studies, National Institute of Ocean Technology (NIOT) is heading this project. The indigenously developed vehicle is capable of crawling on the sea bed at a depth of six kilometer for 72 hours. Project is part MoES plan to mine rare earth metals from ocean floor. The project is expected to become a reality by 2021-22.

It is envisaged that 10% of recovery of sea floor large reserve can meet the energy requirement of India for the next 100 years. It has been estimated that 380 million metric tonnes of polymetallic nodules are available at the bottom of the seas in the Central Indian Ocean.