SEARCHING FOR EVIDENCE OF THE CHICXULUB IMPACT: DETRITAL ZIRCON GEOCHRONOLOGY OF THE K-PG BOUNDARY AT MOSCOW LANDING AL USA

Determining the direct influence of large impacts on the biosphere requires accurately identifying the impact events in the geologic record. The K-Pg site at Moscow Landing Alabama is a well-documented and well-preserved K-Pg locality, but the formation of this boundary locality remains under debate. Unusual, discontinuous sand deposits, formally known as Clayton sands, lie in between the Cretaceous Prairie Bluff Chalk and the overlying Paleogene Clayton formation. Research suggests the Clayton sands were formed by incised valley fill during an early Paleogene transgression or by megawaves produced by the Chicxulub impact.

We have undertaken a geochemical and geochronologic survey of the Clayton sand bodies to answer 2 major questions: 1.what is the provenance of the sand bodies; and their relationship to the overlying Clayton formation proper; and 2. Is there any signatures related to the Chicxulub impact? Alabama is approximately 1200 km from the Chicxulub impact structure and this distance has remained relatively unchanged since the impact event making it an excellent location to study the local effects if large bolide impacts. For this geochronology study we will utilize detrital zircon. Zircon is very durable mineral that can preserve both its original crystallization age and subsequent reheating events as well as planar deformation features and hence it is widely used to correlate impacts in the stratigraphic record. Detrital zircons found in the Clayton sands will be able to help unravel the complicated geologic history preserved at Moscow Landing.