Report

A Late Triassic Impact Ejecta Layer in Southwestern Britain

+ See all authors and affiliations

Science  13 Dec 2002:
Vol. 298, Issue 5601, pp. 2185-2188
DOI: 10.1126/science.1076249

You are currently viewing the abstract.

View Full Text

Abstract

Despite the 160 or so known terrestrial impact craters of Phanerozoic age, equivalent ejecta deposits within distal sedimentary successions are rare. We report a Triassic deposit in southwestern Britain that contains spherules and shocked quartz, characteristic of an impact ejecta layer. Inter- and intragranular potassium feldspar from the deposit yields an argon-argon age of 214 ± 2.5 million years old. This is within the age range of several known Triassic impact craters, the two closest of which, both in age and location, are Manicouagan in northeastern Canada and Rochechouart in central France. The ejecta deposit provides an important sedimentary record of an extraterrestrial impact in the Mesozoic that will help to decipher the number and effect of impact events, the source and dynamics of the event that left this distinctive sedimentary marker, and the relation of this ejecta layer to the timing of extinctions in the fossil record.

  • * To whom correspondence should be addressed. E-mail: spherules{at}abdn.ac.uk

View Full Text

Related Content