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Ever noticed a dark, well-defined sear thru lighter-coloured rocks?
You've stumbled upon a dyke/dike - a vertical sheet of rock formed in the fracture of older rock faces!
Across the #DeccanPlateau, dykes are common & are indicative of continental rifting processes.
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You've stumbled upon a dyke/dike - a vertical sheet of rock formed in the fracture of older rock faces!
Across the #DeccanPlateau, dykes are common & are indicative of continental rifting processes.
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On the Indian subcontinent, there are several regions where dykes occur (maps below).
Dykes exhibit different geochemical features that can help understand their formation.
The Eastern Dharwad Craton, covering parts of #Karnataka & #AndhraPradesh has distinct magmatic dykes.
Dykes exhibit different geochemical features that can help understand their formation.
The Eastern Dharwad Craton, covering parts of #Karnataka & #AndhraPradesh has distinct magmatic dykes.
Magmatic dykes formed when magma intruded into a crack/fracture & crystallized into a sheet cutting across other rock layers.
Dykes vary in thickness & are always younger than the surrounding rock.
Often they occur in swarms - many dykes formed during a single intrusive event.
Dykes vary in thickness & are always younger than the surrounding rock.
Often they occur in swarms - many dykes formed during a single intrusive event.
These images were taken on the outskirts of # #Bengaluru, #Karnataka - a north-south dyke formed along a granitic gneiss boundary.
Granite - the dark, volcanic rocks, juxtaposed against the textured light-and-dark gneiss, are indicative of intense heat/pressure during formation.
Granite - the dark, volcanic rocks, juxtaposed against the textured light-and-dark gneiss, are indicative of intense heat/pressure during formation.
So, why are #dykes important?
- Served as conduits for magma to be transferred from mantle to upper crust
- Will outlast the surrounding rock, and can be used as chronological markers between different metamorphic formations
- Can be easily traced via satellite remote sensing
- Served as conduits for magma to be transferred from mantle to upper crust
- Will outlast the surrounding rock, and can be used as chronological markers between different metamorphic formations
- Can be easily traced via satellite remote sensing
The magnetic orientation of #dykes is quite distinct, and can help trace major periods of continental rifting, and supercontinent fragmentation.
Thereby, dykes lend support to Wegener's #ContinentalDrift theory.
There's more...
Thereby, dykes lend support to Wegener's #ContinentalDrift theory.
There's more...
Some #dykes contain economically viable mineral deposits.
Namely, platinum, palladium, rhodium, ruthenium, iridium & osmium (together known as the PGE group of metals), gold, diamonds, nickel, chromium, cobalt, and other base metals.
Ref: https://www.researchgate.net/publication/260981117_Indian_Dykes_Through_Space_and_Time_Retrospect_and_Prospect#pf4
FIN/
Namely, platinum, palladium, rhodium, ruthenium, iridium & osmium (together known as the PGE group of metals), gold, diamonds, nickel, chromium, cobalt, and other base metals.
Ref: https://www.researchgate.net/publication/260981117_Indian_Dykes_Through_Space_and_Time_Retrospect_and_Prospect#pf4
FIN/
P.S - just remembered this tweet from almost a year ago.
A #dyke photographed in Chittoor district, #AndhraPradesh, #India.
Would love to see more photos from across the country - bring it on
https://twitter.com/Geo_Sophist/status/1159796712707219457?s=19
A #dyke photographed in Chittoor district, #AndhraPradesh, #India.
Would love to see more photos from across the country - bring it on
https://twitter.com/Geo_Sophist/status/1159796712707219457?s=19
