Skip to main content

Geologic and tectonic framework of the Indian shield


 Major Terms and Regions Explained

1. Indian Shield

  • The Indian Shield refers to the ancient, stable core of the Indian Plate made of hard crystalline rocks.

  • It comprises Archean to Proterozoic rocks that have remained tectonically stable over billions of years.

Important Geological Features and Regions

▪️ Ch – Chhattisgarh Basin

  • A sedimentary basin part of the Bastar Craton.

  • Contains rocks of Proterozoic age, mainly sedimentary.

  • Important for understanding the evolution of central India.

▪️ CIS – Central Indian Shear Zone

  • A major tectonic shear zone, separating the Bundelkhand and Bastar cratons.

  • It records intense deformation and metamorphism.

  • Acts as a suture zone, marking ancient tectonic collisions.

▪️ GR – Godavari Rift

  • A rift valley formed due to stretching and thinning of the Earth's crust.

  • Associated with sedimentary basins and hydrocarbon resources.

▪️ M – Madras Block

  • An Archean crustal block in southern India.

  • Composed mainly of granite gneiss and granulite rocks.

▪️ Mk – Malanjkhand

  • Hosts one of the largest copper deposits in India.

  • Located in central India, part of the Sausar mobile belt.

▪️ MR – Mahanadi Rift

  • A tectonic rift valley linked to sediment deposition and basin evolution in eastern India.

▪️ N – Nilgiri Block

  • A crustal block in southern India with high-grade metamorphic rocks.

▪️ NS – Narmada-Son Fault Zone

  • A major east-west tectonic fault dividing northern and southern Indian cratonic blocks.

  • Tectonically very active and important for understanding earthquakes and crustal deformation.

▪️ PC – Palghat-Cauvery Shear Zone

  • A shear zone in southern India dividing the Dharwar craton from the southern granulite terrain.

▪️ R – Rengali Province and Kerajang Shear Zone

  • Lies adjacent to the Singhbhum craton.

  • Shows tectonic activity and shear deformation, significant for Proterozoic tectonics.

▪️ S – Singhbhum Shear Zone

  • Associated with the Singhbhum craton, rich in iron and copper deposits.

  • Records complex deformation and Proterozoic magmatic events.

▪️ V – Vindhyan Basin

  • A large Proterozoic sedimentary basin, covering parts of central India.

  • Contains fossil-bearing rocks and helps understand early life and environments.

Important Rock Units and Geological Provinces

▪️ Neoproterozoic to Phanerozoic cover (including Himalayan orogen)

  • Covers younger rocks (less than 1000 million years).

  • Includes sediments and rocks formed during the formation of the Himalayas.

▪️ Deccan Flood Basalt Province

  • Huge area covered by volcanic basalt flows from the Late Cretaceous (about 65 million years ago).

  • Important for understanding mass extinctions and mantle plume activity.

▪️ Central Indian Tectonic Zone

  • A complex suture zone where different cratons (like Bundelkhand and Bastar) joined.

  • Records deep crustal processes and mountain-building events.

▪️ Shear Zones (general)

  • Zones where rocks have been intensely deformed and displaced.

  • Act as boundaries between geological blocks or terranes.

▪️ Proterozoic Mafic Dyke Swarm

  • Vertical or steeply inclined intrusive bodies of mafic rocks (rich in iron and magnesium).

  • Indicate crustal extension and magmatic events during the Proterozoic.

▪️ Late Paleoproterozoic to Neoproterozoic rocks

  • Rocks formed between 2 billion to 541 million years ago.

  • Include volcanics, sediments, and metamorphic rocks.

▪️ Neoarchean Closepet Granite

  • A large granite intrusion in the Dharwar Craton (~2.5 billion years old).

  • Key marker of continental crust formation.

▪️ Archean TTG + Granite-Greenstone Terrane

  • TTG: Tonalite-Trondhjemite-Granodiorite – common in ancient continental crust.

  • Greenstone belts: Metamorphosed volcanic-sedimentary sequences.

  • Together form the core of the oldest cratonic blocks in India like the Dharwar, Singhbhum, and Bastar cratons.



Geographical Terminologies & Concepts

🔸 Structural and Tectonic Features

  1. Shield – A large area of exposed Precambrian crystalline igneous and metamorphic rocks that form tectonically stable regions.

  2. Shear Zone – A zone of intense deformation in the Earth's crust, usually caused by tectonic forces.

  3. Fault Zone – A fracture or zone of fractures in the Earth's crust along which movement has occurred.

  4. Rift/Rift Valley – A linear-shaped lowland between highlands or mountain ranges created by the action of a geologic rift or fault.

  5. Tectonic Zone – A region influenced by large-scale movements of the Earth's lithosphere.

  6. Suture Zone – A major fault where two tectonic plates or terranes have joined together.

🔸 Geological Time Periods

  1. Archean – The oldest eon of Earth's history (>2.5 billion years ago).

  2. Paleoproterozoic – The earliest part of the Proterozoic Eon (2.5 to 1.6 billion years ago).

  3. Neoproterozoic – The last era of the Proterozoic Eon (1 billion to 541 million years ago).

  4. Phanerozoic – The current eon, starting around 541 million years ago.

🔸 Geological Formations & Units

  1. TTG (Tonalite-Trondhjemite-Granodiorite) – A suite of intrusive igneous rocks typical of ancient continental crust.

  2. Granite-Greenstone Terrane – Regions composed of greenstone belts (volcanic/sedimentary rocks) and granitic intrusions.

  3. Granite – A coarse-grained igneous rock composed mostly of quartz, feldspar, and mica.

  4. Dyke Swarm – A group of parallel or radiating igneous dykes intruded in the crust.

  5. Basalt – A dark, fine-grained volcanic rock, typically found in flood basalt provinces.

🔸 Geological Structures and Provinces

  1. Deccan Flood Basalt Province – A massive volcanic province formed by extensive basalt lava flows during the Late Cretaceous.

  2. Craton – An old and stable part of the continental lithosphere.

  3. Closepet Granite – A specific Neoarchean granite belt found in southern India.

  4. Sedimentary Basin – A low area on Earth where sediments accumulate over time.

  5. Mobile Belt – A region of the Earth's crust that has been affected by tectonic activity, unlike stable cratons.

🧭 Locations and Geologic Regions

  1. Ch – Chhattisgarh Basin – A Proterozoic sedimentary basin in central India.

  2. CIS – Central Indian Shear Zone – A major tectonic boundary in central India.

  3. GR – Godavari Rift – A tectonic rift zone in eastern India.

  4. M – Madras Block – A southern Indian crustal block.

  5. Mk – Malanjkhand – Known for India's largest copper deposit.

  6. MR – Mahanadi Rift – A rifted basin in eastern India.

  7. N – Nilgiri Block – A crustal block in the southern Indian highlands.

  8. NS – Narmada-Son Fault Zone – A prominent east-west fault zone dividing north and south India.

  9. PC – Palghat-Cauvery Shear Zone – A major tectonic boundary in southern India.

  10. R – Rengali Province and Kerajang Shear Zone – Located near the eastern craton boundary.

  11. S – Singhbhum Shear Zone – Associated with the mineral-rich Singhbhum Craton.

  12. V – Vindhyan Basin – A large sedimentary basin with Proterozoic rock sequences.

Other Key Geological Concepts

  1. Metamorphism – The alteration of the composition or structure of a rock by heat, pressure, or other natural agencies.

  2. Crustal Evolution – The process of formation and differentiation of Earth's crust over time.

  3. Continental Collision – A tectonic process where two continental plates converge.

  4. Magmatism – The movement and solidification of magma within the crust.

  5. Basement Rocks – The oldest rocks in a region, forming the foundation beneath younger rocks.

  6. Sedimentation – The process of deposition of mineral and organic particles.



https://geogisgeo.blogspot.com/2023/10/geology-and-tectonic-indian-shield.html

Comments

Post a Comment

Popular posts from this blog

Geology and Tectonic. Indian Shield

1. Ch (Chattisgarh Basin): Chattisgarh Basin is a geological region in central India known for its sedimentary rock formations. It's important for its mineral resources, including coal and iron ore. 2. CIS (Central Indian Shear Zone): CIS is a tectonic boundary in central India where the Indian Plate interacts with the Eurasian Plate. It's characterized by significant faulting and seismic activity. 3. GR (Godavari Rift): The Godavari Rift is a geological feature associated with the rifting and splitting of the Indian Plate. It's located in the Godavari River basin in southeastern India. 4. M (Madras Block): The Madras Block is a stable continental block in southern India. It's part of the Indian Plate and is not associated with active tectonic processes. 5. Mk (Malanjkhand): Malanjkhand is known for its copper deposits and is one of the largest copper mines in India. 6. MR (Mahanadi Rift): The Mahanadi Rift is a geological feature related to the rifting of the Indian Pl...
Post a Comment
Read more

Solar Radiation and Remote Sensing

Satellite Remote Sensing Satellite remote sensing is the science of acquiring information about Earth's surface and atmosphere without physical contact , using sensors mounted on satellites. These sensors detect and record electromagnetic radiation (EMR) that is either emitted or reflected from the Earth's surface. Solar Radiation & Earth's Energy Balance Solar Radiation is the primary source of energy for Earth's climate system. It originates from the Sun and travels through space as electromagnetic waves . Incoming Shortwave Solar Radiation (insolation) consists mostly of ultraviolet, visible, and near-infrared wavelengths . When it reaches Earth, it can be: Absorbed by the atmosphere, clouds, or surface Reflected back to space Scattered by atmospheric particles Outgoing Longwave Radiation is the infrared energy emitted by Earth back into space after absorbing solar energy. This process helps maintain Earth's thermal bala...
Post a Comment
Read more

Morpho-Tectonic Framework of India

The MorphoTectonic Framework of India refers to the combined study of the country's landforms (morphology) and its geological tectonic features. This framework provides insights into how geological forces have shaped India's topography over millions of years. Here's a breakdown of this concept: 1. Morphology: This aspect focuses on the physical features and landforms of India. It includes the study of mountains, plateaus, plains, valleys, rivers, and other surface features. For example, the Himalayas, Western Ghats, IndoGangetic Plains, and Deccan Plateau are prominent morphological features of India. 2. Tectonics: Tectonics deals with the movement and deformation of the Earth's lithosphere (the outermost rigid layer of the Earth). In the case of India, it primarily involves the interactions of the Indian Plate with neighboring tectonic plates. India is situated at the convergence of several major tectonic boundaries:     Collision with the Eurasian Plate: The most sign...
Post a Comment
Read more

Neighbourhood Operations

 Neighbourhood Operations in GIS? In GIS and raster data , neighbourhood operations look at a group of nearby pixels (not just one) to understand or change a pixel's value. Think of it like checking what's around a house before deciding what color to paint it! Why "Neighbourhood"? Each pixel has " neighbours " (just like how your house has nearby houses). Neighbourhood operations check these nearby pixels and do some calculation to get a new value. 1. Aggregations (Summarizing Nearby Values) Aggregation means combining values of several pixels into one. We do this to: Find the average of surrounding pixels Find the minimum or maximum value Smooth the map (make it less rough) 🧒🏻 Example: Imagine checking the test scores of 9 students sitting around you and finding the average score . That's aggregation!  2. Filtering Techniques Filtering is used to improve or highlight features in a raster image, just like f...
Post a Comment
Read more

India – Geographic Location – Spatial Significance

India's geographic location holds immense spatial significance due to its position on the world map. Here's an explanation of India's geographic location and its spatial significance: Geographic Location: India is a vast South Asian country located on the Indian subcontinent. Its geographic coordinates are approximately between 8°4'N and 37°6'N latitude and 68°7'E and 97°25'E longitude. It is surrounded by several important bodies of water: - To the west, it has a coastline along the Arabian Sea. - To the east, it is bordered by the Bay of Bengal. - To the south, it faces the Indian Ocean. - To the north, India shares its land borders with Pakistan, China, Nepal, Bhutan, Bangladesh, and Myanmar. Spatial Significance: 1. Strategic Location: India's location places it at the crossroads of South Asia and the Indian Ocean region. This strategic position has made it historically important for trade, diplomacy, and geopolitics. 2. Trade and Commerce: India...
Post a Comment
Read more