Neotethys Oceanic Plate and Tectonic Movements | 19 Feb 2025

Source: SD 

Why in News? 

A study has revealed that the ancient Neotethys oceanic plate, which once lay between the Arabian and Eurasian continental tectonic plates, is breaking apart under the Zagros Mountains in West Asia due to plate movement. 

• This impacts regional geography, earthquakes, and resource distribution offering valuable insights into the Earth's deep tectonic processes. 

What is Neotethys Oceanic Plate? 

• The Neotethys Oceanic Plate was an ancient oceanic plate that once formed the seafloor of the Neotethys Ocean, which existed during the breakup of Pangaea.  
• Over time, it was subducted into the Earth's mantle beneath the Eurasian continent as the Arabian and Eurasian plates moved closer. 

What is Tectonic Plates and its Movement? 

• About: A tectonic plate (also called lithospheric plate) is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic plates. 
  • Continental plates form the Earth's landmasses, while oceanic plates lie beneath the ocean floor. 
  • Oceanic plates are composed of denser basaltic rocks and subducted beneath continental plates at convergent boundaries, as continental plates consist of lighter granitic rocks. 
• Major and Minor Tectonic Plates: Earth's lithosphere is divided into 7 major plates and several minor plates. 
  • Major Plates: Antarctic Plate, North American Plate, South American Plate, Pacific Plate, Indo-Australian Plate, African Plate, Eurasian Plate. 
  • Minor Plates: Cocos Plate, Nazca Plate, Arabian Plate, Philippine Plate, Caroline Plate, Fiji Plate, Juan de Fuca Plate, etc. 

• Tectonic Plate Movement: 
  • Movement of Plates: The tectonic plates are not fixed but constantly move horizontally over the asthenosphere as rigid units. 
    • Their interactions- colliding, diverging, or sliding past each other result in geological events like earthquakes and volcanic eruptions. 
  • Rate of Movement: Tectonic plates move at varying speeds. The Arctic Ridge has the slowest movement (<2.5 cm/year), while the East Pacific Rise in the South Pacific moves the fastest (>15 cm/year). 
  • Driving Force: The movement is driven by convection currents in the mantle which occur due to primordial heat from Earth's formation and radioactive decay of isotopes like thorium and uranium. 
    • Heated material rises, spreads, cools, and sinks, creating a continuous cycle that propels the plates. 
• Tectonic Plate Boundaries: 
  • Convergent Boundaries (Destructive Boundaries): Plates collide, leading to subduction, mountain formation, and volcanic arcs. 
    • Oceanic-Continental Convergence: The denser oceanic plate subducts beneath the continental plate (e.g., Juan de Fuca Plate subducting under the North American Plate). 
    • Oceanic-Oceanic Convergence: The denser plate subducts, forming deep trenches and island arcs (e.g., Mariana Trench). 
    • Continental-Continental Convergence: Collision results in mountain formation (e.g., Himalayas due to the Indian and Eurasian plate collision). 
  • Divergent Boundaries (Constructive Boundaries): Plates move apart, creating new crust, seafloor spreading, and rift valleys. 
    • Oceanic Divergence: Mid-ocean ridges form (e.g., Mid-Atlantic Ridge). 
    • Continental Divergence: Rift valleys emerge (e.g., Great Rift Valley in Africa). 
  • Transform Boundaries (Conservative Boundaries): Plates slide past each other without creating or destroying crust. 
    • They often cause earthquakes due to accumulated stress along faults (e.g., San Andreas Fault in California).