Constraining the Geological Time Scale for the Upper Cretaceous in the Edmonton Group: Western Canadian Sedimentary Basin
Abstract
The Cretaceous period records evidence of sea-level changes, remarkably cyclic sedimentation, major perturbations in carbon cycles during anoxic events, and large scale igneous activity. Astronomically-tuned time scales are only partially consistent with recalculated Ar-Ar constraints for the Cretaceous-Paleogene (K-Pg) boundary, but differ in number and tuning of 405-kyr eccentricity related cycles. The exposures of Upper Cretaceous strata along the Red Deer River (Western Canadian Sedimentary Basin) offer a unique opportunity to examine aspects of marine, tectonic, and climatic influenced sediments. The uppermost part of the Knudsen Farm section is a well-preserved continuous section, mainly composed by climatically controlled alternations of silt and organic rich horizons, in which altered volcanic ash layers have been deposited. In this section, the K-Pg boundary has been placed at the base of a prominent coal layer (Nevis coal), approx. 24 m from the base of the c29r. We present a compilation of paleomagnetic data, chemical, colour and magnetic susceptibility proxies, and Ar-Ar, K-Ar and U-Pb (CA-TIMS) for the uppermost part of the Maastrichtian, including the base of the c29r to the K-Pg boundary and up to the lowermost Danian. High-resolution radioisotopic ages and the multi-proxy lithological and geochemical datasets are used to develop a cyclostratigraphic reconstruction of this interval, thus permitting the synchronisation of rock clocks close to the K-Pg boundary. This research is funded by the European Community's Seventh Framework Program (FP7/2007-2013) under grant agreement no [215458].
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.V51A2505H
- Keywords:
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- 1100 GEOCHRONOLOGY;
- 1500 GEOMAGNETISM AND PALEOMAGNETISM;
- 4946 PALEOCEANOGRAPHY / Milankovitch theory;
- 9610 INFORMATION RELATED TO GEOLOGIC TIME / Cretaceous