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Deccan Traps

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The Deccan Traps are a massive igneous province located in west-central India.

India Geology Zones
India Geology Zones

This feature is one of the largest volcanic structures on our planet. It consists of many thick layers of solidified flood basalt. These layers were created by lava flowing from multiple volcanic centers. The total volume of these rocks is approximately 500,000 cubic kilometers. Originally, the lava may have covered an area as large as 1.5 million square kilometers. This would be about half the size of modern India.

Deccan Traps Maharashtra India 22Mar2018 SkySat
Deccan Traps Maharashtra India 22Mar2018 SkySat

Today, the visible area is smaller due to erosion and plate tectonics.

Geologists believe these eruptions were caused by a deep mantle plume. A mantle plume is a rising column of hot rock from deep inside the Earth. This specific plume is known as the Réunion hotspot. This hotspot is still active today near the Mascarene Islands in the Indian Ocean. The plume likely caused the eruptions and helped pull India away from Africa. This process is called rifting, where the Earth's crust pulls apart. As the Indian plate moved north over the plume, massive amounts of magma reached the surface.

Deccan Traps volcano
Deccan Traps volcano

This movement is supported by data showing rapid plate motion during the eruptions.

Most of the lava arrived through a process called fissure eruptions. Instead of erupting from a single mountain peak, the lava flowed out of long cracks in the ground. These eruptions occurred over a period of 600,000 to 800,000 years. Most of the activity happened between 66.3 and 65.6 million years ago. This timeframe spans the Cretaceous–Paleogene boundary, a major turning point in Earth's history. Some scientists believe a major pulse of these eruptions lasted less than 30,000 years. However, dating these exact moments is difficult because the transitions happened so quickly.

Western-Ghats-Matheran
Western-Ghats-Matheran

The province is divided into several distinct parts and layers. Geographically, it includes the main Deccan, the Malwa Plateau, the Mandla Lobe, and the Saurashtran Plateau. Scientists also group the rocks into three stratigraphic units: the Upper, Middle, and Lower traps. These groups are thought to relate to the distance from the original eruption sites. Chemically, the province can be split into as many as eleven different formations. About 95% of the lava is made of tholeiitic basalt. This rock contains minerals like olivine, pyroxenes, and plagioclase.

Tholeiitic basalt (GeoDIL number - 459)
Tholeiitic basalt (GeoDIL number - 459)

There is a famous scientific debate regarding the Deccan Traps and the mass extinction of dinosaurs. Some researchers, such as Gerta Keller, suggested volcanic gases caused the extinction. Gases like sulfur dioxide can change the climate by blocking sunlight. One study found that these gases might have caused a temperature drop of 5°C for 10,000 years. However, most scientists now believe the Chicxulub impact in North America was the primary cause. This impact created an "impact winter" that killed many living things. Some studies suggest the Deccan eruptions may have actually helped negate some impact effects.

Epistilbite-Calcite-170550
Epistilbite-Calcite-170550

Despite the massive volcanic activity, the layers of rock have preserved many fossils. These fossils are often found in the Intertrappean Beds between layers of lava. Scientists have discovered ancient freshwater molluscs and early ancestors of modern frogs. One notable species is the toothed frog, known as Indobatrachus. Another famous fossil is the frog Oxyglossus pusillus. These biological remains provide a window into the life of the Late Cretaceous period.

Rajasaurus en las traps del decán
Rajasaurus en las traps del decán

They show how life survived or changed during these intense geological events.

The study of the Deccan Traps connects many different scientific fields. It links geology with biology through the study of fossils. It also connects plate tectonics with climate science. By studying the chemical signatures in the basalt, scientists learn about the deep mantle. The movement of the Indian and African plates helps us understand how continents move. Even the name of the region tells a story of its history. "Deccan" comes from the Sanskrit word for "southern," while "trap" comes from the Swedish word for "stairs."

Ajanta caves 1
Ajanta caves 1

This is because the layered hills look like giant stone steps.

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🖼️ Images & Media (9)
File:India Geology Zones.jpg
India Geology Zones.jpg
File:Western-Ghats-Matheran.jpg
Western-Ghats-Matheran.jpg
File:Deccan Traps Maharashtra India 22Mar2018 SkySat.jpg
Deccan Traps Maharashtra India 22Mar2018...
File:Deccan traps.png
Deccan traps.png
File:Ajanta caves 1.JPG
Ajanta caves 1.JPG
File:Tholeiitic basalt (GeoDIL number - 459).jpg
Tholeiitic basalt (GeoDIL number - 459).jpg
File:Epistilbite-Calcite-170550.jpg
Epistilbite-Calcite-170550.jpg
File:Rajasaurus en las traps del decán.jpg
Rajasaurus en las traps del decán.jpg
File:Deccan Traps volcano.jpg
Deccan Traps volcano.jpg
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