EGU21-8196, updated on 04 Mar 2021
https://doi.org/10.5194/egusphere-egu21-8196
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Carbon isotope and sequence stratigraphy of the upper Isachsen Formation on Axel Heiberg Island (Nunavut, Canada): High Arctic expression of oceanic anoxic event 1a in a deltaic environment

Wolf Dummann1, Claudia Schröder-Adams2, Peter Hofmann3, Janet Rethemeyer3, and Jens O. Herrle1
Wolf Dummann et al.
  • 1Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main, Germany (wdummann@uni-koeln.de)
  • 2Department of Earth Sciences, Carleton University, Ottawa, Canada
  • 3Institute of Geology and Mineralogy, University of Cologne, Cologne, Germany

Oceanic anoxic event (OAE) 1a documents a major perturbation of the Early Cretaceous global carbon cycle with severe consequences for the ocean-climate-biosphere system. While numerous studies over the past decades have provided a relatively detailed picture of the environmental repercussions of OAE 1a at low and mid-latitudes, studies from high latitudes, in particular the High Arctic, are limited. In this study, we present a high-resolution carbon isotopic and sequence stratigraphic framework for the lower to lower upper Aptian interval of the Isachsen Formation of the High Arctic Sverdrup Basin (Canada). These data enable us to precisely locate the stratigraphic position of OAE 1a in a deltaic sedimentary environment. The carbon isotope record allows, for the first time, identification of the different carbon isotope segments (CISs) of OAE 1a in the Sverdrup Basin and thereby correlation of the High Arctic record with sections from lower latitudes. Based on this improved chemostratigraphy, we revise the age of upper Paterson Island, Rondon, and Walker Island Members, important regional lithostratigraphic marker units. Whole-rock geochemical data record two episodes of marine incursion into the Sverdrup Basin during OAE 1a (CISs Ap3 and Ap6), which are interpreted as regional maximum flooding surfaces. This information is used in conjunction with detailed sedimentological logs and geochemical grain-size proxies to refine the sequence stratigraphic framework for the upper Isachsen Formation. We propose that transgressive-regressive cycles in the Sverdrup Basin were mainly controlled by the combined effects of eustatic sea-level changes and regional tectonic uplift, potentially related to the emplacement of Alpha Ridge, which culminated at ca. 122 Ma during CIS Ap9.

How to cite: Dummann, W., Schröder-Adams, C., Hofmann, P., Rethemeyer, J., and Herrle, J. O.: Carbon isotope and sequence stratigraphy of the upper Isachsen Formation on Axel Heiberg Island (Nunavut, Canada): High Arctic expression of oceanic anoxic event 1a in a deltaic environment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8196, https://doi.org/10.5194/egusphere-egu21-8196, 2021.

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