Tectonic Framework of India | Geology Optional Notes for UPSC PDF Download

Tectonic Framework of India

• Physiographic Divisions of India:
  • Peninsular India:
  • Indo-Gangetic Alluvium Plain:
  • Extra-Peninsula:
• Peninsular India Significance:
  • One of the largest Precambrian shield areas globally.
• Geographical Features:
  • Indo-Gangetic Alluvium Plain separates Himalayas and Peninsular Shield.
  • Shillong Plateau in northeast India as an outpost.
• Tectonic Divisions:
  • Correspondence with Physiographic Divisions.
• Peninsular Shield Composition:
  • Comprised of Aravalli, Dharwar, and Singhbhum cratonic regions.
  • Separated by Proterozoic rifts and mobile belts.
• Major Rifts:
  • Narmada Son Lineament (NSL) and Tapti Lineament (TL) as prominent rifts.
  • Son-Narmada Tapti lineament (SONATA) significance.
  • Other rift basins like Kutch, Cambay, Godavari, Cuddapah, etc.

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• Pakistan
  • Location: Bhuj, Khambhat
  • Significance: Hot spot
• Arabia
  • Organizations: BRICA, CBR
  • Establishment: 1956 V in Bombay
• India
  • History: Established in 954 AD
  • Notable Events: GBE in 1938, Klippe in 1993
  • Location: Delhi, Lafur, Hyderabad
• Geological Features
  • Himalayan Region:
    • The Himalayas exhibit high seismic activity compared to Peninsular India.
    • Seismic Vulnerability: Zone V for Himalayan region, less for Peninsular region.
    • Tectonic Units: Divided into four major units spanning over 2400 km.
  • Sub-Himalaya (Churia Hills or Siwaliks):
    • Main Frontal Thrust (MFT) thrusts the Sub-Himalaya over Quaternary alluvium.
    • Active Orogen: Continual activity shown by alluvial deposits from Himalayan rivers.
  • Deccan Traps:
    • Located in Gondwana.
    • Formation: Precambrian sediments.
  • Geological Structures:
    • Fault/Lineament: Formed in 1964.
    • Window: Geological feature at 88 E longitude.

```This HTML structure presents a paraphrased and elaborated version of the provided information on Pakistan, Arabia, India, and various geological features of the region, including the Himalayan region, Sub-Himalaya, Deccan Traps, and other geological structures. Each section is broken down into key points for better understanding.

The Himalayan Geological Structure

• The Lesser Himalaya (LH)

  • The Lesser Himalaya's sediments are thrust over the Subhimalaya via the Main Boundary Thrust (MBT).
  • It is often observed in tectonic windows like Kishtwar or Larji-Kulu-Rampur windows within the High Himalaya Crystalline Sequence.

• The Central Himalayan Domain (CHD) or High Himalaya

  • It serves as the backbone of the Himalayan orogen and covers regions with the highest topographic relief.
  • Commonly divided into four zones:
  • 
    
    • The High Himalayan Crystalline Sequence (HHCS): A significant nappe thrust over the Lesser Himalaya along the Main Central Thrust (MCT).
    • The Tethys Himalaya (TH)
    • The Nyimaling-Tso Morari Metamorphic Dome (NTMD)
    • The Lamayuru and Markha Units (LMU)

• The Indus Suture Zone (ISZ)

  • The ISZ marks the collision area between the Indian Plate and the Ladakh Batholith to the north.
  • Comprised of Ophiolite Mélanges, a mix of flysch and ophiolites from the Neotethys oceanic crust, along with volcanics and molasses.

Seismic Zonation and Crustal Architecture of India

• Indian Ocean: Covers 16% of the Earth's water surface
• Abgleda, Mumbai, Indian Plate: Locations within India
• Lakshadweep: Group of islands in the Indian Ocean
• Rugkee, Jabalpur, Ryan, Lucknow, Latur, PR, Hyderabad, Chennai: Various locations within India
• Depression: Represents a 40m decline in elevation
• Bulge: Indicates a 450m increase in elevation
• Direction of Faulting: R indicates reverse faulting (compressional) earthquakes, T indicates normal faulting (tensile) earthquakes

Geological Survey of India's Research

• Seismic Velocity Structure: 3-D seismic velocity structure studies conducted in the Himalayan region and Peninsular India
• Techniques Used: Seismic inversion techniques with P- and S-wave arrival times recorded to analyze earthquake threats
• Recent Studies: Detailed examination of aftershock sequences from significant earthquakes like the 1993 Killari earthquake, 1999 Chamoli earthquake, and the 2001 Bhuj earthquake
• Seismic Crustal Images: Creation of seismic crustal images of earthquake source areas for better understanding

Indian Sub-continent and Tibetan Plateau Collision

• Collision Impact: Buckling of the Indian sub-continent as it collides with the Tibetan Plateau
• Molasse Formation: The term "molasse" refers to sandstones, shales, and conglomerates formed as terrestrial or shallow marine deposits in front of rising mountain chains

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