Secondary cratering on Earth: The Wyoming impact crater field

Date:
February 14, 2022
Source:
Geological Society of America
Summary:
Several dozen small impact craters, 10--70-m in size, have been
discovered in southeastern Wyoming. A team of U.S. and German
geoscientists found these ancient craters in exposed sedimentary
layers from the Permian period (280 million years ago). After
discovering the first craters, the team initially suspected that
they are a crater-strewn field, formed by the breakup of an asteroid
that entered the atmosphere.

However, with the discovery of more and more craters over a wide
area, this interpretation was ruled out.



FULL STORY ========================================================================== Several dozen small impact craters, 10-70-m in size, have been discovered
in southeastern Wyoming. A team of U.S. and German geoscientists found
these ancient craters in exposed sedimentary layers from the Permian
period (280 million years ago). After discovering the first craters,
the team initially suspected that they are a crater-strewn field, formed
by the breakup of an asteroid that entered the atmosphere. However,
with the discovery of more and more craters over a wide area, this interpretation was ruled out.


==========================================================================
Many of the craters are clustered in groups and are aligned along rays.

Furthermore, several craters are elliptical, allowing the reconstruction
of the incoming paths of the impactors. The reconstructed trajectories
have a radial pattern.

"The trajectories indicate a single source and show that the craters were formed by ejected blocks from a large primary crater," said project
leader Thomas Kenkmann, professor of geology at the University of
Freiburg, Germany.

"Secondary craters around larger craters are well known from other planets
and moons but have never been found on Earth," The team calculated the ballistic trajectories and used mathematical simulations to model the
formation of the craters. All of the craters found so far are located
150-200 km from the presumed primary crater and were formed by blocks
that were 4-8-m in size that struck the Earth at speeds of 700-1000 m/s.

The team estimate that the source crater is about 50-65 km in diameter
and should be deeply buried under younger sediments in the northern
Denver basin near the Wyoming-Nebraska border.

========================================================================== Story Source: Materials provided by Geological_Society_of_America. Note: Content may be edited for style and length.


========================================================================== Related Multimedia:
* Drone_images_of_craters_formed_at_Sheep_Mountain ========================================================================== Journal Reference:
1. Thomas Kenkmann, Louis Mu"ller, Allan Fraser, Doug Cook, Kent
Sundell,
Auriol S.P. Rae. Secondary cratering on Earth: The Wyoming impact
crater field. GSA Bulletin, 2022; DOI: 10.1130/B36196.1 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220214144030.htm

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