The Shiva crater is the claim by

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

Sankar Chatterjee and colleagues that the Bombay High and

Surat Surat (Gujarati Language, Gujarati: ) is a city in the western Indian States and territories of India, state of Gujarat. The word Surat directly translates to ''face'' in Urdu, Gujarati language, Gujarati and Hindi. Located on the banks of t ...

Depression on the Indian continental shelf west of

Mumbai Mumbai ( ; ), also known as Bombay ( ; its official name until 1995), is the capital city of the Indian state of Maharashtra. Mumbai is the financial capital and the most populous city proper of India with an estimated population of 12 ...

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

represent a impact crater, that formed around the Cretaceous-Paleogene boundary. Chatterjee and colleagues have claimed that this could have contributed to the K-Pg extinction event. Other scholars have questioned the claims, finding that there is no evidence of an impact structure.

Arguments

Chatterjee argues that the Shiva crater was formed around 65 million years ago, about the same time as a number of other impact craters and the

Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event, also known as the K–T extinction, was the extinction event, mass extinction of three-quarters of the plant and animal species on Earth approximately 66 million years ago. The event cau ...

(

Cretaceous–Paleogene boundary The Cretaceous–Paleogene (K–Pg) boundary, formerly known as the Cretaceous–Tertiary (K–T) boundary, is a geological signature, usually a thin band of rock containing much more iridium than other bands. The K–Pg boundary marks the end o ...

/ K-Pg boundary). Although the site has shifted since its formation because of sea floor spreading, the formation is approximately long by wide. If its status as an impact crater is ever confirmed, the Shiva crater would be the largest known impact crater on Earth. It is estimated that this proposed crater would have been made by an

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

comet A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun, a process called outgassing. This produces an extended, gravitationally unbound atmosphere or Coma (cometary), coma surrounding ...

approximately in diameter.Chatterjee, S., N. Guven, A. Yoshinobu, and R. Donofrio. (2006) ''Shiva Structure: a possible KT boundary impact crater on the western shelf of India.'' Museum of Texas Tech University Special Publications. 50, 39pp. At the time of the Cretaceous–Paleogene extinction, India was located over the

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. The hotspo ...

of the Indian Ocean. Hot material rising from the mantle flooded portions of India with a vast amount of

lava Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fractu ...

, creating a plateau known as the Deccan Traps. It has been hypothesized that the significant geothermal activity in this region coupled with the impact which caused the crater together set ideal conditions for the maturation of oil and natural gas, which, it is suggested, is the reason for its high rate of occurrence there today.

Geology and morphology

Unlike typical known extraterrestrial impact structures, Shiva is teardrop shaped, roughly . It is also unusually rectangular. Chatterjee argues that the low angle of an impact combined with boundary fault lines and unstable rock led to this unusual formation. The age of the structure is inferred from the Deccan Traps which overlie part of it.

Shiva and mass extinction

The proposed Shiva crater and other possible impact craters along with the

Chicxulub crater The Chicxulub crater is an impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is offshore, but the crater is named after the onshore community of Chicxulub Pueblo (not the larger coastal town of Chicxulub Puerto). I ...

have led to the hypothesis that multiple impacts caused the massive extinction event at the end of the Cretaceous period. Chatterjee is confident that Shiva was one of many impacts, stating that "the K-T extinction was definitely a multiple-impact scenario."Rampino, M. R., and B. M. Haggerty (1996) ''The “Shiva Hypothesis”: Impacts, mass extinctions, and the galaxy.'' Earth, Moon, and Planets. 72(1–3):441–460. Other theories have argued that since the Chicxulub impact is believed by some researchers to have occurred ''earlier'' than the extinction of the non-avian dinosaurs, Shiva's impact was enough to cause the mass extinction by itself.Davis, J. W. (2006)
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''Texas Tech Paleontologist Finds Evidence That Meteorite Strike Near Bombay May Have Wiped Out Dinosaurs.''
Texas Tech Today, Texas Tech University, Lubbock, Texas. An article published in ''

Science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

'' 2013 by Paul R. Renne at the University of California at Berkeley suggests that the Chicxulub crater is in fact within the time frame of when the mass extinction occurred.

Criticism

The claims of an impact crater have been criticised. Christian Koeberl, a professor of geology at the

University of Vienna The University of Vienna (, ) is a public university, public research university in Vienna, Austria. Founded by Rudolf IV, Duke of Austria, Duke Rudolph IV in 1365, it is the oldest university in the German-speaking world and among the largest ...

and a specialist on impact craters, described the claims in 2004 as "a figment of imagination", stating that the claims were "inconsistent not only with the regional geology and geophysics, but also with anything we know about impact cratering." American geologist Gerta Keller stated in 2007, "We have worked extensively throughout India and investigated a number of the localities where Sankar Chatterjee claims to have evidence of a large impact he calls Shiva crater... Unfortunately, we have found no evidence to support his claims. Sorry to say, this is all nonsense." Geophysicist Sean Gulick stated in the same year, "There's a bunch of problems to say the least. There is no evidence that hatterjee ispresenting of it actually being a crater", and described the oval shape of the structure as unlikely for an impact crater. In the chapter "Impact Cratering from an Indian Perspective", from the 2013 book ''Earth System Processes and Disaster Management'', geologists Jayanta K. Pati and Puniti Pati write that "...the proposed Shiva structure in the Arabian Sea to the southwest of the Indian subcontinent (Chatterjee et al. 2006) have also been suggested to be of possible impact origin. However, Chatterjee et al. (2006) do not provide any substantial evidence for the existence of a crater structure and certainly not for the existence of an impact structure at Shiva."

References

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).

by Leslie Mullen for Astrobiology Magazine (Nov. 2004).

Shiva Structure: A Possible KT Boundary Impact Crater on the Western Shelf of India
{{Authority control Impact craters of India Possible impact craters on Earth Cretaceous impact craters Cretaceous–Paleogene boundary Geology of the Indian Ocean