Abstract

Examination of samples from exploration wells in the Arctic Beaufort-Mackenzie Basin has resulted in the documentation of the global Paleocene-Eocene thermal maximum (PETM) interval in 6 out of 12 wells examined. The PETM, a brief period of extreme global warming at about 55 Ma, occurs within the upper part of the deltaic-influenced Aklak Sequence. The PETM was recognized primarily by the occurrence of the dinoflagellate cyst Apectodinium augustum — globally associated with the PETM. Thermophilic pollen, e.g. Intratriporopollenites (Tilia) and Platycaryapollenites, are also associated with the PETM in the Beaufort-Mackenzie Basin wells. Carbon isotope analyses from one well, Natiak O-44, indicate a carbon isotope (δ13C) excursion of about 0.72‰ associated with the A. augustum acme. This excursion is low relative to continental settings for the PETM, but closer to some oceanic values. In Natiak O-44, the PETM interval is unusually thick, at about 100 m. This is consistent, however, with rapid deltaic sedimentation of the Aklak Sequence (nearly 5 km thick). A comparison of palynological and foraminiferal data indicates that the index foraminifera Reticulophragmium boreale becomes extinct at approximately the PETM interval. Furthermore, there is a pronounced foraminiferal turnover at or near the PETM. The turnover is apparently of circum-Arctic extent and caused by the extreme global warming and oceanic change of the Paleocene-Eocene transition. Recognition of the PETM in the Beaufort-Mackenzie Basin provides an important chronostratigraphic datum in complex deltaic sediments that are typically difficult to date precisely.

You do not currently have access to this article.