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In Context
- Recently researchers from the University of Adelaide, Australia, have carried out a new study that includes an updated map of the earth’s tectonic plates.
- The paper “New maps of global geological provinces and tectonic plates” is published in the journal Earth-Science Reviews.
About
- The new model for tectonic plates better explains the spatial distribution of 90 percent of earthquakes and 80 percent of volcanoes from the past two million years.
- Existing models only capture 65 percent of earthquakes.
- The map includes several new microplates to the existing tectonic plate model like the
- Macquarie microplate which sits south of Tasmania and
- The Capricorn microplate which separates the Indian and Australian plates.
- Researchers found that plate boundary zones account for nearly 16% of the Earth’s crust and an even higher proportion, 27%, of continents.
- The new model now includes all the deformation zones north of India as the plate bulldozes its way into Eurasia.
Significance
- The map will help in forming a better understanding of natural hazards like earthquakes and volcanoes.
- The province model can be used for further exploration of minerals and the orogeny model.
- The orogeny model helps to understand the evolution of geodynamic systems
- It will help in better understanding of the evolution of the earth.
Plate Tectonic Theory/Plate Tectonic
- This concept was formulated in the 1960s by Alfred Wegener.
- According to the theory, Earth has a rigid outer layer, known as the lithosphere, which is typically about 100 km (60 miles) thick and overlies a plastic (moldable, partially molten) layer called the asthenosphere.
- The lithosphere is broken up into:
- seven very large continental- and ocean-sized plates,
- six or seven medium-sized regional plates, and
- several small plates.
- These plates move relative to each other.
- They typically move at rates of 5 to 10 cm (2 to 4 inches) per year, and interact along their boundaries.
- They converge, diverge, or slip past one another.
- Mountain formation:
- Plate motions cause mountains to rise where plates push together or converge.
- Ocean formation:
- Continents fracture and oceans are formed where plates pull apart or diverge.
- The continents are embedded in the plates and drift passively with them, which over millions of years results in significant changes in Earth’s geography.
- Such interactions are thought to be responsible for most of Earth’s seismic and volcanic activity, although earthquakes and volcanoes can occur in plate interiors.
Supercontinent Vaalbara
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Evidence of Plate Tectonic Theory
- Continent Puzzle:
- The continents fit together almost like puzzle pieces forming Pangaea (one super-continent).
- Fossil evidence:
- Fossils on different continents are similar to fossils on continents that were once connected.
- When the continents split, different life forms developed.
- Distributions of rocks:
- Most distributions of rocks within Earth’s crust, including minerals, fossil fuels, and energy resources, are a direct result of the history of plate motions and collisions and the corresponding changes in the configurations of the continents and ocean basins.
- Sea floor spreading:
- Seafloor spreading theory validated the Plate Tectonics Theory.
- As per the theory, the ocean floor is always moving from the mid-oceanic ridge towards the trenches.
- Hot basaltic magma rises and erupts at the ridge. It cools down to become a new seafloor at this juncture.
- The newly formed seafloor at the ocean crust then gradually moves away from the ridge and its place is taken by a newer seafloor and the cycle repeats.
- In the process the older rocks move farther away from the spreading zone while younger rocks will be found nearer to the spreading zone.
- The entire process looks like a conveyor belt.
Seven Major Plates
Some important minor Plates
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Source: DTE
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