2006 Philadelphia Annual Meeting (2225 October 2006)
Paper No. 119-3
Presentation Time: 1:30 PM-5:30 PM

ANNEALING THE CHICXULUB IMPACT: TERTIARY YUCATAN CARBONATE PLATFORM DEVELOPMENT AND BASIN INFILLING

PEARSON, Zulmacristina F.1, WHALEN, Michael T.1, GULICK, Sean2, and NORRIS, Richard3, (1) Department of Geology and Geophysics, University of Alaska Fairbanks, P.O. Box 755780, Fairbanks, AK 99775, ftzfr@uaf.edu, (2) The Institute for Geophysics, The Univ of Texas at Austin, 4412 Spicewodd Springs Rd. Bldg 600, Austin, TX 78759, (3) Geosciences Research Division, Scripps Institution of Oceanography, MS-0244, La Jolla, CA 92093

The Yucatan Peninsula and the southern Gulf of Mexico contain a record of one of the most important impact events in the Earth history, the Chicxulub impact at the Cretaceous-Tertiary (K/T) boundary. We report here a preliminary integration of sequence stratigraphic analysis of the Tertiary basin imaged in offshore 1996 and 2005 seismic data, and sedimentologic and stratigraphic analysis of the Tertiary sediments in the Yaxcopoil-1 drill core (YAX-1).

Interpretation of the 2-D seismic data sets indicate a series at least seven seismic units from the K/T boundary to the seafloor. The lowermost Unit A sits conformably atop the K/T boundary reflector, and is characterized by a set of strong sub-parallel reflectors that onlap the peak ring. We interpret this package as the first pelagic sediments in the basin that may correlate with the lower 100-115 m of YAX-1. Foram biostratigraphic data indicate that this section of the core spans Paleocene through the lower Eocene. The lower 100 m is characterized by coarse-grained redeposited carbonate facies and soft-sediment deformed units interbedded with fine-grained carbonates. Some units display normal grading while others are chaotic or crudely graded. The upper 15 m of logged core is characterized by repetitive m-scale cycles of marl grading up into wacke/packstones. The redeposited and soft sediment deformed carbonates record patterns of sedimentation typical of slopes undergoing readjustment and regrading, as one would expect along a newly created steep slope.

Unit B, overlying Unit A, consists of a package of parallel reflectors. Overlying Unit B on the edges of the inner crater is a series of sigmoidal clinoforms (Unit C); the reflector separating Units B and C can be mapped throughout the inner crater and the pre-existing basin to the northeast. Unit D overlies Unit B in the center of the crater and onlaps Unit C at the edges, and is in turn overlain by a comfortable package, Unit E. By Unit E time the center basin was largely filled and the sediment depocenter for Unit F, which included a phase of clinoform development, was confined to the northeast basin. Unit G lies above an erosional surface that may have formed near lowstand. This surface can be mapped more easily to the north, but is likely a regional event. Integration of Units B through G with the core data from YAX-1 is ongoing.

2006 Philadelphia Annual Meeting (2225 October 2006)
General Information for this Meeting
Session No. 119--Booth# 119
Impact Craters: Structures, Drilling, Ages, and Geophysics (Posters)
Pennsylvania Convention Center: Exhibit Hall C
1:30 PM-5:30 PM, Monday, 23 October 2006

Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 297

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