Pantasma: Evidence for a Pleistocene circa 14 km diameter impact crater in Nicaragua

1P. Rochette, 2R. Alaç3P. Beck,2G. Brocard,4A. J. Cavosie,5V. Debaille,1B. Devouard,4F. Jourdan,6,7B. Mougel,1F. Moustard,6F. Moynier,8S. Nomade,9G. R. Osinski,10B. Reynard,11J. Cornec
Meteoritics & Planetary Science (in Press) Link to Article []
1Aix‐Marseille Univ., CNRS, INRA, IRD, Coll. France, CEREGE, 13545 Aix‐en‐Provence, France
2Basin Genesis Hub, School of Geosciences, University of Sydney, Sydney, Australia
3Univ Grenoble Alpes, CNRS, IPAG, , 38041 Grenoble, France
4Space Science and Technology Centre and The Institute for Geoscience Research (TIGeR), School of Earth and Planetary Science, Curtin University, Perth, Western Australia, Australia
5Laboratoire G‐Time, Université Libre de Bruxelles, Brussels, Belgium
6Institut de Physique du Globe de Paris, Université Sorbonne Paris Cité, CNRS UMR 7154, Paris, France
7Centro de geociencias, Universidad Nacional Autónoma de México, Campus Juriquilla, Querétaro
8LSCE, CEA, , 91190 Gif sur Yvette, France
9Centre for Planetary Science and Exploration and Department of Earth Science, University of Western Ontario, London, Canada
10University of Lyon, ENS de Lyon, Université Claude Bernard Lyon 1, , 69007 Lyon, France
11Geologist, Denver, USA
Published by arrangement with John Wiley & Sons

The circa 14 km diameter Pantasma circular structure in Oligocene volcanic rocks in Nicaragua is here studied for the first time to understand its origin. Geomorphology, field mapping, and petrographic and geochemical investigations all are consistent with an impact origin for the Pantasma structure. Observations supporting an impact origin include outward‐dipping volcanic flows, the presence of former melt‐bearing polymict breccia, impact glass (with lechatelierite and low H2O, <300 ppm), and also a possible ejecta layer containing Paleozoic rocks which originated from hundreds of meters below the surface. Diagnostic evidence for impact is provided by detection in impact glass of the former presence of reidite in granular zircon as well as coesite, and extraterrestrial ε54Cr value in polymict breccia. Two 40Ar/39Ar plateau ages with a combined weighted mean age of 815 ± 11 ka (2 σ; P = 0.17) were obtained on impact glass. This age is consistent with geomorphological data and erosion modeling, which all suggest a rather young crater. Pantasma is only the fourth exposed crater >10 km found in the Americas south of N30 latitude, and provides further evidence that a significant number of impact craters may remain to be discovered in Central and South America.


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