A chemostratigraphic method to determine the end of impact-related sedimentation at marine-target impact craters (Chesapeake Bay, Lockne, Tvären)

Meteoritics and Planetary Science
By: , and 

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Abstract

To better understand the impact cratering process and its environmental consequences at the local to global scale, it is important to know when in the geological record of an impact crater the impact-related processes cease. In many instances, this occurs with the end of early crater modification, leaving an obvious sedimentological boundary between impactites and secular sediments. However, in marine-target craters the transition from early crater collapse (i.e., water resurge) to postimpact sedimentation can appear gradual. With the a priori assumption that the reworked target materials of the resurge deposits have a different chemical composition to the secular sediments we use chemostratigraphy (δ13Ccarb, %Corg, major elements) of sediments from the Chesapeake Bay, Lockne, and Tvären craters, to define this boundary. We show that the end of impact-related sedimentation in these cases is fairly rapid, and does not necessarily coincide with a visual boundary (e.g., grain size shift). Therefore, in some cases, the boundary is more precisely determined by chemostratigraphy, especially carbonate carbon isotope variations, rather than by visual inspection. It is also shown how chemostratigraphy can confirm the age of marine-target craters that were previously determined by biostratigraphy; by comparing postimpact carbon isotope trends with established regional trends.

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Publication type Article
Publication Subtype Journal Article
Title A chemostratigraphic method to determine the end of impact-related sedimentation at marine-target impact craters (Chesapeake Bay, Lockne, Tvären)
Series title Meteoritics and Planetary Science
DOI 10.1111/j.1945-5100.2010.01084.x
Volume 45
Issue 7
Year Published 2010
Language English
Publisher Wiley
Contributing office(s) Eastern Geology and Paleoclimate Science Center
Description 19 p.
First page 1206
Last page 1224
Country Sweden, United States
Other Geospatial Chesapeake Bay, Lockne crater, Tvären crater
Online Only (Y/N) N
Additional Online Files (Y/N) N
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