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Keywords:

  • impact paleomagnetism

[1] Eight circular structures along the 38th parallel in the mid-continent United States are hypothesized to have formed from multiple impacts. Only two of these structures have been confirmed as impact features and they are not well dated. In this study we use paleomagnetic data to constrain the timing of the poorly dated Decaturville impact structure (Missouri) and the Weaubleau feature (Missouri), interpreted to be an impact structure, to evaluate the possibility of a serial impact event. A post depositional, mid Permian pole derived from impact-related breccias at Decaturville, as well as crosscutting relationships, show a Pennsylvanian-mid Permian age for the structure. A post-tilting Late Mississippian pole from deformed strata at Weaubleau indicates that the deformation event can be no younger than Late Mississippian. Our results demonstrate that the Decaturville and Weaubleau structures are of different ages and could not have been caused by a serial impact event.