Tectonic plates and Rifting
Context: Recent studies show that Africa’s splitting plates could give birth to a new ocean, but with consequences.
- It explains how major landforms on earth were created as a result of Earth’s subterranean movement.
- A tectonic plate or a lithospheric plate is a massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.
- Tectonic plates are sometimes subdivided into three categories: major (or primary) plates, minor (or secondary) plates, and microplates (or tertiary plates).
Major plates of Earth:-
- African Plate
- Antarctic Plate
- Eurasian Plate
- Indo-Australian plate
- North American Plate
- Pacific Plate
- South American Plate
Minor Plates of the Earth:-
- Cocos plate: Between Central America and the Pacific plate
- Nazca plate: Between South America and the Pacific plate
- Arabian plate: Mostly the Saudi Arabian landmass
- Philippine plate: Between the Asiatic and Pacific plate
- Caroline plate: Between the Philippine and Indian plates (North of New Guinea)
- Fuji plate: North-east of Australia
- Juan De Fuca’s plate
- Major geomorphological features such as fold and block mountains, mid-oceanic ridges, trenches, volcanism, earthquakes etc. are a direct consequence of the interaction between various Tectonic Plates (lithospheric plates).
- There are three ways in which the plates interact with each other.
- In this kind of interaction, the plates diverge (move away from each other).
- Mid-ocean ridges (e.g. the Mid-Atlantic Ridge) are formed due to this kind of interaction.
- Here, the basaltic magma erupts and moves apart (seafloor spreading).
- Example: On continents, East African Rift Valley is the most important geomorphological feature formed due to the divergence of African and Somali plates.
- In this kind of interaction, two lithospheric plates collide with each other.
- The zone of collision may undergo crumpling and folding, and folded mountains may emerge (orogenic collision).
- Himalayan Boundary Fault is one such example.
- When one of the plates is an oceanic plate, it gets embedded in the softer asthenosphere of the continental plate, and as a result, trenches are formed at the zone of subduction.
- In this kind of interaction, two plates slide past each other.
- There is no creation or destruction of the landform but only the deformation of the existing landform.
- In oceans, transform faults are the planes of separation generally perpendicular to the mid-oceanic ridges.
- Example: San Andreas Fault (Silicon Valley lies dangerously close to the faultline) along the western coast of the USA Tectonic plates d Rifting