Cretaceous Arctic Siliceous Phytoplankton Productivity: Potential for Regional Biostratigraphic Correlation and Paleoenvironmental Reconstruction
David Harwood1, Kevin McCartney2, and Jakub Witkowski3
1Earth and Atmospheric Sciences, Univ. of Nebraska-Lincoln, Lincoln, NE.
2Environmental Studies, Univ. of Maine at Presque Isle, Presque Isle, ME.
3Historical and Regional Geology, Faculty of Geology, Univ. of Warsaw, Warsaw, Poland.
Diatom and silicoflagellate microfossils are abundant in Upper Cretaceous marine sediments of the Canadian High Arctic. Their high abundance, wide distribution, rapid evolutionary rates, and environmental specificity offers new opportunities for biostratigraphic correlation, paleoenvironmental reconstruction, and patterns of temporal siliceous biogenic sedimentation that have yet to be realized. Diverse siliceous microfossil assemblages (>120 diatom taxa in >50 genera, and >45 silicoflagellate taxa in 8 genera) are newly described from stratigraphic sections exposed in the Canadian Mackenzie Delta region (Smoking Hills and Mason River formations), and Arctic Platform (Devon Island) and central Sverdrup Basin (Amund Ringnes Is.), chiefly in the Kanguk Formation. These results led to the construction of new biostratigraphic schemes for diatoms and silicoflagellates to divide the Cenomanian through Maastrictian interval into seven silicoflagellate zones and five diatom zones. Similar assemblages of microfossils are also known from the Russian Arctic margin and Ural Mountians, indicating the potential for wide application of this biostratigraphic framework. This provides an enhanced ability to resolve and correlate global geological events (e.g. OAEs, 90 Ma hyperthermal, etc.) across Arctic Cretaceous sequences. We anticipate that further studies will provide new paleoenvironmental information to resolve or refute episodes of suggested Cretaceous Arctic glaciation, timing of Arctic Ocean marine connections and ventilation, and to better understand seasonality in productivity and water column stratification, and variable rates of organic matter production and burial. Although the opal-A skeletons of these microfossils are not stable under conditions of deep burial, information about diatom production and widespread biogenic sedimentation across the Arctic Ocean and margin can be extracted from stratigraphic sections that underwent <1000 m burial, and applied to subsiding basins. This contribution will report on these new results to enhance chronostratigraphic control for the Cretaceous Arctic Ocean and marginal seas, and to understand paleoeclimate and paleoenvironmental controls on diatom productivity in the high latitude Cretaceous ocean.
AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.���������������������������������������������������������������������������