Shiva crater


The Shiva Crater is a geologic structure, which is hypothesized by Sankar Chatterjee and colleagues to be a diameter impact structure. This geologic structure consists of the Bombay High and Surat Depression. They lie beneath the Indian continental shelf and the Arabian Sea west of Mumbai, India. Chatterjee named this structure after Shiva, the Hindu god of destruction and renewal. It is presently on the list of probable impact craters and is rated '1' based on three-step confidence level criteria of Anna Mikheeva of Russian Academy of Sciences, applied to the impact sites that have appeared several times in the literature and/or have been endorsed by the Impact Field Studies Group and/or Expert Database on Earth Impact Structures.

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. Although the site has shifted since its formation because of sea floor spreading, the formation is approximately long by wide. 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 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.

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 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." 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. Evidence published in a 2013 Science article 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.

Footnotes