Asteroid impact crater – 14 km in diameter discovered in Nicaragua
The first detailed study of a large circular depression 14 kilometres in diameter in the mountains of northern Nicaragua, named Pantasma, shows that it resulted from the impact of an asteroid 800,000 years ago. Evidence of this impact comes from the detection of two phases of high pressure and traces of extraterrestrial matter. Pantasma is the first impact crater to be discovered in Central America, and only the fourth on Earth over ten kilometres long and less than three million years old.
Publication date: 18/03/2019
Press, Research
Related teams :
Cosmochemistry, Astrophysics and Experimental Geophysics (CAGE)
Related themes : Origins
A large circular depression 14 kilometres in diameter in the volcanic rocks of the mountains of northern Nicaragua, named Pantasma, was until now thought to be the result of a volcanic collapse. However, a field study carried out in 2016 and the petrological and geochemical analyses of the material collected show that this depression is the result of an asteroid impact that is thought to have taken place 800,000 years ago, an event much more recent than the local volcanism. The analyses in this study, published in the journal Meteoritics and Planetary Science, were carried out by an international team of researchers from France (CEREGE, IPAG, IPGP, LSCE and LGL-TPE), Australia, Belgium and Canada.
Argon/Argon radiochronology was used to date the glass produced by the impact. The formation of this glass during an impact is demonstrated by the very low water content and the presence of two high-pressure phases polymorphous with quartz and zircon: coesite and reidite. Conditions during the impact are estimated at a temperature in excess of 2000°C and a pressure in excess of 30 GPa. An impact breccia found in the centre of the crater reveals traces of extraterrestrial material, as demonstrated by chromium isotope ratios. The isotopic composition of the impactor from the asteroid belt corresponds to an ordinary chondrite. Pantasma is the first impact crater discovered in Central America, and only the fourth over ten kilometres and less than three million years old known on Earth (along with the Bosumtwi crater in Ghana, Zhamanshin in Kazakhstan and Hiawatha in Greenland, published in 2018).
The modification of the crater’s shape by the very active erosion of the region has been modelled and is compatible with the age of the impact. This discovery confirms that there are still many large craters exposed at the surface to be discovered on Earth, preferably in remote regions (such as Greenland) or little-studied regions (Africa, Latin America, Asia), where the density of known large craters is on average five times lower than in Europe, North America and Australia. The first group of continents has only fourteen craters larger than ten kilometres exposed at the surface, half as many as the second group, even though its surface area is more than twice as large.
The authors also propose to test the hypothesis that the field of distal impact glasses (tectites) discovered in Belize by petroleum geologist Jean Cornec, 500 km further north, originated from the Pantasma crater. The Argon/Argon ages match, as do the isotopic and chemical compositions. The Belize tectite/Pantasma crater pair has very similar characteristics to the Côte d’Ivoire tectite/Bosumtwi crater pair, including the same type of impactor.
Find out more:
- P. Rochette, R. Alaç, P. Beck, G. Brocard, A. J. Cavosie, V. Debaille, B. Devouard, F. Jourdan, B. Mougel, F. Moustard, F. Moynier, S. Nomade, G. R. Osinski B. Reynard and J. Cornec. Pantasma: Evidence for a Pleistocene circa 14 km diameter impact crater in Nicaragua Meteoritics and Planetary Science (2019) doi: 10.1111/maps.13244
- The French laboratories involved are the Centre européen de recherche et d’enseignement de géosciences de l’environnement (CEREGE, Aix-Marseille Univ./CNRS/INRA/IRD/Coll. France), the Institut de planétologie et astrophysique de Grenoble (IPAG, Univ Grenoble Alpes/CNRS), the Institut de physique du globe de Paris (IPGP, Univ. Sorbonne Paris Cité/CNRS/IPGP), the Laboratoire des sciences du climat et de l’environnement (LSCE, CEA/CNRS/UVSQ/IPSL) and the Laboratoire de géologie de Lyon (LGL-TPE, University of Lyon/ENS Lyon/CNRS).
