Signatures of intra-crater seiches of IODP-ICDP Expedition 364 (Site M0077) in the Chicxulub Crater

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http://meetingorganizer.copernicus.org/EGU2018/EGU2018-11331-1.pdf
Author(s): Smit, Jan; Whalen, Michael T.; Bralower, Timothy J.; Kaskes, Pim; de Graaff, Sietze J.; de Beeck, Sander Op; Vandijck, Ruben; de Winter, Niels J.; Goderis, Steven; Vellekoop, Johan; Claeys, Philippe
Author Affiliation(s): Primary:
Vrije Universiteit Amsterdam, Faculty of Sciences, Amsterdam, Netherlands
Other:
University of Alaska at Fairbanks, United States
Pennsylvania State University, United States
Vrije Universiteit Brussel, Belgium
Katholieke Universiteit Leuven, Belgium
Volume Title: European Geosciences Union general assembly 2018
Source: Geophysical Research Abstracts, Vol.20; European Geosciences Union general assembly 2018, Vienna, Austria, April 8-13, 2018. Publisher: Copernicus GmbH on behalf of the European Geosciences Union (EGU), Katlenburg-Lindau, Germany. ISSN: 1029-7006
Note: In English. 2 refs.
Summary: The topmost impact related unit of Hole M0077 of the joint IODP-ICDP expedition 364 on the peak ring of the Chicxulub impact structure in Mexico, is a 76cm thick graded silty 'transitional interval' from 616.58-617.34 mbsf. It occurs just below the basal Paleocene background crater filling of pelagic limestone/marl and contains the main and Ni, Cr, Ir anomaly in the uppermost part. Elsewhere such unit had been termed "KPg boundary cocktail" a) and represents the final settling of fine particles out of a suspended, turbulent cloud of sediment in the aftermath of the impact disturbance. Although the entire 76 cm is a graded siltstone, it contains many thin laminations of very fine sand that locally display a peculiar type of micro cross-bedding. The cross-bedding pinches and swells, and bears a reminiscence to aeolian type of cross-bedding, albeit on a much smaller scale (sub-cm vs. tens of meters). Typical of aeolian cross-bedding is the often highly variable angle of the fore-set laminations within a cross-bed set due to ever changing wind directions and strength. We assume that this micro-crossbedding in the transitional interval is also deposited under weak, but highly variable current strength and possibly current directions. The mechanism we hypothesize here is that just after the resurge of the sea in the Chicxulub crater a seiche developed within the crater and oscillated many times across the entire crater basin before it was dampened out completely only at the very top of the transitional interval. Similar laminations and crossbedding were observed in the corresponding interval of ICDP drill core Yaxopoil-1, and at the top of the tsunami-sequence around the Gulf of Mexico, e.g. La Lajilla and Mimbral,b), indicating that after passage of the first tsunami waves, the enclosed Gulf of Mexico basin numerous seiches were generated during deposition of the main Ir influx. a)Bralower, T.J.et al 1998, Geology 26, p331.b)Smit et al 1994, GSA spec.Pap 307, p151. [Copyright Author(s) 2018. CC Attribution 4.0 License: https://creativecommons.org/licenses/by/4.0/legalcode]
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Cenozoic; Chicxulub Crater; Cretaceous; Cross-bedding; Expedition 364; Gulf of Mexico; IODP Site M0077; International Ocean Discovery Program; K-Pg boundary; Lower Paleocene; Marine environment; Mesozoic; North Atlantic; Paleo-oceanography; Paleocene; Paleoenvironment; Paleogene; Planar bedding structures; Sedimentary structures; Seiches; Stratigraphic boundary; Tertiary; Upper Cretaceous
Coordinates: N212701 N212701 W0895658 W0895658
Record ID: 2018093345
Copyright Information: GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from European Geosciences Union, Munich, Germany