Shiva crater
Encyclopedia
The Shiva crater is a sea floor structure located beneath the Indian Ocean
, west of Mumbai
, India
. It was named by the paleontologist Sankar Chatterjee
after Shiva
, the Hindu
god of destruction and renewal.
Its age is estimated to be around 65 million years, created at about the same time as a number of other impact craters and the Cretaceous-Tertiary extinction event
(K-T boundary). Although the site has shifted since its formation because of sea floor spreading, the formation is approximately 600 kilometres (372.8 mi) long by 400 km (248.5 mi) wide. It is estimated that a crater of that size would have been made by an asteroid
or comet
approximately 40 km (24.9 mi) in diameter.
The Shiva complex adds weight to the theory that the K-T extinction was caused by a massive asteroid fragmenting and hitting the Earth in several locations, known as the "multiple impact theory".
At the time of the K-T extinction, India was located over the Réunion hotspot
of the Indian Ocean. Hot material rising from the mantle
flooded portions of India with a vast amount of lava
, creating a plateau known as the Deccan Traps
. It has been hypothesized that either the crater or the Deccan Traps associated with the area are the reason for the high level of oil and natural gas reserves in the region.
There is some debate within the academic community over whether the "Shiva Crater" is indeed an impact crater.
The age of the crater is inferred from the Deccan traps, which contain relatively high amounts of iridium
(an element extremely rare in the Earth's crust but more common in asteroids). The crater also contains larger than average amounts of alkaline melt rocks, shocked quartz
, and iron oxide laced with iridium; these types of rocks and features suggest an impact origin. In addition, the K-T boundary layer in India is one meter thick. Assuming that the clay layer is the remains of scattered deposits from an asteroid impact, the thick layer would suggest that the actual impact occurred near India.
site has led to the hypothesis that there were in fact multiple impacts which caused the massive extinction event at the end of the Cretaceous period. Other theories have argued that since the Chicxulub impact is believed by some researchers to have occurred earlier than the extinction of the dinosaurs, Shiva's impact was enough to cause the mass extinction.
While Chatterjee is confident that Shiva was one of many impacts, stating that "the K-T extinction was definitely a multiple-impact scenario," other scientists remain unconvinced that the extinction event was caused by multiple impacts, or that the Shiva feature is even in fact a crater. An article in the journal Nature
suggested another supposed impact feature at Silverpit
was in fact a sinkhole depression.
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
, west of Mumbai
Mumbai
Mumbai , formerly known as Bombay in English, is the capital of the Indian state of Maharashtra. It is the most populous city in India, and the fourth most populous city in the world, with a total metropolitan area population of approximately 20.5 million...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. It was named by the paleontologist Sankar Chatterjee
Sankar Chatterjee
Sankar Chatterjee is a paleontologist, and is the Paul W. Horn Professor of Geosciences at Texas Tech University and Curator of Paleontology at the Museum of Texas Tech University. He earned his Ph. D. from the University of Calcutta in 1970 and was a Post-doctoral Fellow at the Smithsonian...
after Shiva
Shiva
Shiva is a major Hindu deity, and is the destroyer god or transformer among the Trimurti, the Hindu Trinity of the primary aspects of the divine. God Shiva is a yogi who has notice of everything that happens in the world and is the main aspect of life. Yet one with great power lives a life of a...
, the Hindu
Hinduism
Hinduism is the predominant and indigenous religious tradition of the Indian Subcontinent. Hinduism is known to its followers as , amongst many other expressions...
god of destruction and renewal.
Its age is estimated to be around 65 million years, created at about the same time as a number of other impact craters and the Cretaceous-Tertiary extinction event
Cretaceous-Tertiary extinction event
The Cretaceous–Paleogene extinction event, formerly named and still commonly referred to as the Cretaceous-Tertiary extinction event, occurred approximately 65.5 million years ago at the end of the Maastrichtian age of the Cretaceous period. It was a large-scale mass extinction of animal and plant...
(K-T boundary). Although the site has shifted since its formation because of sea floor spreading, the formation is approximately 600 kilometres (372.8 mi) long by 400 km (248.5 mi) wide. It is estimated that a crater of that size would have been made by an asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
or comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
approximately 40 km (24.9 mi) in diameter.
The Shiva complex adds weight to the theory that the K-T extinction was caused by a massive asteroid fragmenting and hitting the Earth in several locations, known as the "multiple impact theory".
At the time of the K-T extinction, India was located over the Réunion hotspot
Réunion hotspot
The Réunion hotspot is a volcanic hotspot which currently lies under the Island of Réunion in the Indian Ocean. The Chagos-Laccadive Ridge and the southern part of the Mascarene Plateau are volcanic traces of the Réunion hotspot....
of the Indian Ocean. Hot material rising from the mantle
Mantle (geology)
The mantle is a part of a terrestrial planet or other rocky body large enough to have differentiation by density. The interior of the Earth, similar to the other terrestrial planets, is chemically divided into layers. The mantle is a highly viscous layer between the crust and the outer core....
flooded portions of India with a vast amount of lava
Flood basalt
A flood basalt or trap basalt is the result of a giant volcanic eruption or series of eruptions that coats large stretches of land or the ocean floor with basalt lava. Flood basalts have occurred on continental scales in prehistory, creating great plateaus and mountain ranges...
, creating a plateau known as the Deccan Traps
Deccan Traps
The Deccan Traps are a large igneous province located on the Deccan Plateau of west-central India and one of the largest volcanic features on Earth. They consist of multiple layers of solidified flood basalt that together are more than thick and cover an area of and a volume of...
. It has been hypothesized that either the crater or the Deccan Traps associated with the area are the reason for the high level of oil and natural gas reserves in the region.
There is some debate within the academic community over whether the "Shiva Crater" is indeed an impact crater.
Geology and morphology
Unlike many known crater formations, the Shiva complex is teardrop shaped, roughly 600 kilometre. The complex itself is also unusually rectangular. Chatterjee hypothesizes that the low angle of an impact combined with boundary fault lines and unstable rock led to this unusual formation; other researchers have noted that rock faults and impacts could modify the crater shape. Similar to craters of its large size, the Shiva complex has concentric rings with a collapsed outer rim and a central spire- Shiva's is as high as Mount Everest.The age of the crater is inferred from the Deccan traps, which contain relatively high amounts of iridium
Iridium
Iridium is the chemical element with atomic number 77, and is represented by the symbol Ir. A very hard, brittle, silvery-white transition metal of the platinum family, iridium is the second-densest element and is the most corrosion-resistant metal, even at temperatures as high as 2000 °C...
(an element extremely rare in the Earth's crust but more common in asteroids). The crater also contains larger than average amounts of alkaline melt rocks, shocked quartz
Shocked quartz
Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure , the crystalline structure of quartz will be deformed along planes inside the crystal...
, and iron oxide laced with iridium; these types of rocks and features suggest an impact origin. In addition, the K-T boundary layer in India is one meter thick. Assuming that the clay layer is the remains of scattered deposits from an asteroid impact, the thick layer would suggest that the actual impact occurred near India.
Shiva and mass extinction
The discovery of Shiva and other features similar to impact craters like the ChicxulubChicxulub Crater
The Chicxulub crater is an ancient impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named...
site has led to the hypothesis that there were in fact multiple impacts which caused the massive extinction event at the end of the Cretaceous period. Other theories have argued that since the Chicxulub impact is believed by some researchers to have occurred earlier than the extinction of the dinosaurs, Shiva's impact was enough to cause the mass extinction.
While Chatterjee is confident that Shiva was one of many impacts, stating that "the K-T extinction was definitely a multiple-impact scenario," other scientists remain unconvinced that the extinction event was caused by multiple impacts, or that the Shiva feature is even in fact a crater. An article in the journal Nature
Nature (journal)
Nature, first published on 4 November 1869, is ranked the world's most cited interdisciplinary scientific journal by the Science Edition of the 2010 Journal Citation Reports...
suggested another supposed impact feature at Silverpit
Silverpit crater
Silverpit crater is a buried sub-sea structure under the North Sea off the coast of the United Kingdom. The crater-like form, named after the Silver Pit — a nearby sea-floor valley recognized by generations of fishermen — was discovered during the routine analysis of seismic data collected during...
was in fact a sinkhole depression.
External links
- The Shiva Crater: Implications for Deccan Volcanism, India-seychelles Rifting, Dinosaur Extinction, and Petroleum Entrapment at the Kt Boundary by Chatterjee, Sankar; Guven, Necip; Yoshinobu, Aaaron; and Donofrio, Richard; Paper No. 60-8, 2003 Seattle Annual Meeting of Geological Society of America (November 2–5, 2003).
- Deep Impact - Shiva: Another K-T Impact? by Leslie Mullen for Astrobiology Magazine (Nov. 2004).