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 (
Cretaceous–Paleogene boundary / 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 or
comet approximately in diameter. At the time of the Cretaceous–Paleogene 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 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. 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. An article published in
Science 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 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 [Chatterjee is] presenting 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." == See also ==