DECCAN TRAPS

 

A view of the Ajanta Caves excavated in the gorge wall of the Waghur/Waghora River. The caves, listed as a World Heritage Site, are excavated in compound lava flows. The Buddhist cave monuments date from 2nd century BCE to 6th century CE 

(Photo courtesy of Francesca Lugeri)

At the end of the Cretaceous, the western part of peninsular India underwent numerous volcanic eruptions that resulted in the formation of the Deccan Traps. A total of 48 lava flows have been identified within the Deccan Traps, with a maximum thickness of about 2.5 km on the western side of the plateau near Mumbai. The Deccan Traps are spread over half a million square kilometers in the west-central parts of India, and they occupy huge areas of the states of Maharashtra and Karnataka. India also has the longest lava flows known to be preserved. They are estimated to be 1500 km long and drain out into the Gulf of Bengal near Rajahmundry in Karnataka.

Many archaeological monuments like the Buddhist, Hindu, and Jain temples of Ajanta, Ellora, and Elephanta are the oldest in-situ basalt cave temples, dating back to the second century. They also have the oldest known cave paintings on the Indian subcontinent. However, this title could be snatched by the recent discoveries in Mangar Bani, near the outskirts of Delhi.

At least 4 of the UNESCO World Heritage Sites in India, like the Ajanta, Ellora, and Elephanta cave temples, and the Chhatrapati Shivaji Maharaj Terminus (formerly Victoria Terminus), is made of this basalt.

Deccan basalts are in high demand worldwide and are mined for a variety of purposes including masonry stone, road metal, and as a raw material for corrosion-resistant basaltic pipes and basalt wool.

Quarrying of Deccan basalt is done in the western Deccan Plateau region, especially around Navi Mumbai, Aurangabad, Jalgaon, Nashik, and Kolhapur.

Basalt is a dark-colored, fine-grained, extrusive igneous rock (i.e., the molten rock or lava cooled on the surface) 

Basalt flows cover about 70% of the Earth’s surface and huge areas of terrestrial planets.

They come from the mantle. When rocks melt under pressure and temperature, they then make their way up to the surface via ducts and feed fissure volcanoes on the surface.

Future studies could gather more evidence about the environmental conditions that led to the mass extinction of non-avian dinosaurs and gigantic reptiles. 

The massive Deccan volcanic mountain ranges of the Western Ghats (east of Mumbai) reach up to a height of 3500 m and consist entirely of layered lava flows. (photo courtesy of G. Keller)

THE DAY DINOSAURS DIED

Artist depiction of the Asteroid 

Credit – Scotese Paleomap project (this map shows the position of continents when the cretaceous Paleogene mass extinction occurred )

Do you know what happened on the very day dinosaurs died?

Well, according to the latest research done by geologists, it was the spring season in the Northern Hemisphere ( Autumn in the southern hemisphere) when the dino-killing asteroid smashed into the Yucatán Peninsula, off the coast of Mexico (present-day Chixulub).

In a paper recently published in nature, scientists used fossils from a site in North America in North Dakota’s southwest region known as Tanis.

The fossils were deposited by a seiche in a river. seiche is similar to a tsunami wave, but it happens inland, perhaps due to a strong earthquake.

The fossils of the fish present here contained glass spherules that were created due to the asteroid impact, which threw a large amount of molten rock material into space. The liquid rock crystallized, & cooled in space, and fell back down all over the planet. The fish that lived here ingested these and got trapped inside them.

Further researchers were able to figure out the season using the bones of fish.

The timing of the impact was also crucial from our point of view because, during spring, mammals hibernate underground and were very lucky when the asteroid struck

The asteroid that struck the Yucatán Peninsula 66 million years ago, was at least the size of Mount Everest. It managed to wipe out more than 70 % of all life present on Earth during that time, including the non-avian dinosaurs & giant reptiles.

This event is officially known as the "Cretaceous Paleogene (K- Pg) mass extinction".

The initial impact itself released energy equivalent to billions of nuclear weapons all at once. Thermal radiation melted & vaporized anything within a radius of 1500 km, & the impact debris caused the atmosphere to heat up.

The remainder of the energy was transferred into the Earth's crust, resulting in magnitude 11 earthquakes and volcanic eruptions.

Massive wildfires raged for months across the globe, releasing aerosols and soot into the upper atmosphere, causing temperatures to plummet and the planet to enter a period of darkness comparable to a nuclear winter. Global photosynthesis was halted due to a lack of sunlight, but fungi thrived on the corpses left behind.

Some debates are still raging on this issue, as the Deccan Traps of India were erupting before the Asteroid struck, either way, it seems that the Global ecosystem was already collapsing 66 million years ago.

You can learn more about this topic on -

Palaeocast | Palaeontology podcasts

BBC One and David Attenborough to reveal the final day of the dinosaurs - Media Centre

https://youtu.be/dFCbJmgeHmA