Editing Verneshot

{{short description|Hypothetical volcanic eruption caused by buildup of gas under a craton}}
{{Use dmy dates|date=October 2020}}
{{singlesource|date=July 2019}}
A '''verneshot''' (named after French author [[Jules Verne]]) is a hypothetical [[volcanic eruption]] event caused by the buildup of gas deep underneath a [[craton]]. Such an event may be forceful enough to launch an extreme amount of material from the [[crust (geology)|crust]] and [[mantle (geology)|mantle]] into a [[sub-orbital]] [[trajectory]], leading to significant further damage after the material crashes back down to the surface.

== Connection with mass extinctions ==

Verneshots have been proposed as a causal mechanism explaining the statistically unlikely contemporaneous occurrence of continental [[flood basalt]]s, [[mass extinction]]s, and "impact signals" (such as [[planar deformation features]], [[shocked quartz]], and [[iridium anomaly|iridium anomalies]]) traditionally considered definitive evidence of hypervelocity [[impact event]]s.<ref name="Morgan_CME">{{cite journal|last1=Phipps Morgan |first1=J. |last2=Reston |first2=T. J. |last3=Ranero |first3=C. R. |date=15 January 2004 |title=Contemporaneous mass extinctions, continental flood basalts, and 'impact signals': are mantle plume-induced lithospheric gas explosions the causal link? |journal=[[Earth and Planetary Science Letters]] |volume=217 |issue=3–4 |pages=263–284 |doi=10.1016/S0012-821X(03)00602-2 |url=http://www.geo.cornell.edu/eas/PeoplePlaces/Faculty/JPM/VerneshotEPSL2004.pdf|bibcode=2004E&PSL.217..263P }}<!-- paywall url: linkinghub.elsevier.com/retrieve/pii/s0012821x03006022 --> (First submitted 17 April 2003). For an informal introduction ''see'' [http://www.engineering.cornell.edu/faculty/new-faculty/new-faculty-2004/Jason-Phipps-Morgan.cfm Professor Jason Phipps Morgan's faculty biography] {{webarchive |url=https://web.archive.org/web/20060922215311/http://www.engineering.cornell.edu/faculty/new-faculty/new-faculty-2004/Jason-Phipps-Morgan.cfm |date=22 September 2006 }} at Cornell University from May 2004: ''I became interested in the causes of mass-extinctions, in particular worrying about the 'too-many-coincidences' problem that these periods appear to be associated (if we believe what's published in the mainstream literature) with BOTH extremely rare continental flood basalts and continental rifting, and even rarer 'impact signals' commonly presumed to come from large extraterrestrial bolide impacts. Our recently published Verneshot hypothesis is our best guess on how to explain these coincidences in a self-consistent causal manner.'''</ref>

The verneshot theory suggests that [[mantle plume]]s may cause heating and the buildup of [[carbon dioxide]] gas underneath continental [[lithosphere]]. If continental [[rift]]ing occurs above this location, an explosive release of the built up gas may occur, potentially sending out a column of crust and mantle into a globally dispersive, super-[[stratosphere|stratospheric]] trajectory. It is unclear whether such a column could stay coherent through this process, or whether the force of this process would result in it shattering into much smaller pieces before impacting. The pipe through which the magma and gas had travelled would collapse during this process, sending a shockwave at hypersonic velocity that would deform the surrounding [[craton]].

A verneshot event is likely to be related to nearby continental flood basalt events, which may occur before, during or after the verneshot event. This may help in searching for evidence for the results of verneshot events; however, it is also quite probable that most of such evidence will be buried underneath the basalt flows, making investigation difficult. J. Phipps Morgan and others have suggested that subcircular [[bouguer anomaly|Bouguer gravity anomalies]] recognized beneath the [[Deccan Traps]] may indicate the presence of verneshot pipes related to the [[Cretaceous–Paleogene extinction event]].<ref name ="Morgan_CME"/>

If the Deccan Traps were the location of a verneshot event at the [[Cretaceous–Paleogene boundary]], the strong iridium spike at the Cretaceous–Paleogene boundary could be explained by the iridium-rich nature of volatiles in the Reunion mantle plume, which is currently beneath [[Piton de la Fournaise]], but during the end Cretaceous was located beneath India in the area of the Deccan Traps; the verneshot event could potentially distribute the iridium globally.<ref name ="Morgan_CME"/>

== Tunguska event ==
A verneshot has been proposed as an alternate explanation for the [[Tunguska event]], widely regarded as the result of an atmospheric explosion of a small comet or asteroid. Arguments offered for this mechanism include the lack of extraterrestrial material at the event site, the lack of a credible impact structure, and the presence of shocked quartz in surface outcrops.<ref>{{cite journal |last1=Vannucchi |first1=Paola |last2=Morgan |first2=Jason P. |last3=Della Lunga |first3=Damiano |last4=Andronicos |first4=Christopher L. |last5=Morgan |first5=W. Jason |title=Direct evidence of ancient shock metamorphism at the site of the 1908 Tunguska event |journal=Earth and Planetary Science Letters |date=January 2015 |volume=409 |pages=168–174 |doi=10.1016/j.epsl.2014.11.001|bibcode=2015E&PSL.409..168V |url=https://zenodo.org/record/894872 }}</ref> However, this hypothesis has not been generally accepted, with [[Mark Boslough]] arguing that there is no basis for rejecting the impact hypothesis.<ref>{{cite journal |last1=Cohen |first1=David |title=Tugnuska 100 years on |journal=New Scientist |date=25 June 2008 |volume=198 |issue=2662 |pages=38–41 |doi=10.1016/S0262-4079(08)61618-8}}</ref>

== Name ==

In 1865 [[Jules Verne]]'s novel ''[[From the Earth to the Moon]]'' introduced the concept of a [[Ballistics|ballistic]] projectile escaping the Earth's gravity, from which Phipps Morgan and others derived the name "Verneshot" in their paper theorizing a connection between extinction events and cratonic gas ejection.

==References==
{{reflist}}

{{Jules Verne}}
{{Global catastrophic risks}}

[[Category:Volcanology]]
[[Category:Jules Verne]]
[[Category:Extinction events]]
[[Category:Geological hazards]]
[[Category:Doomsday scenarios]]
[[Category:Natural disasters]]
[[Category:Tunguska event]]