Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Clim. Past, 13, 855-878, 2017
https://doi.org/10.5194/cp-13-855-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
14 Jul 2017
Water-mass evolution in the Cretaceous Western Interior Seaway of North America and equatorial Atlantic
James S. Eldrett1, Paul Dodsworth2, Steven C. Bergman3, Milly Wright4, and Daniel Minisini3 1Shell International Exploration & Production B.V, Kesslerpark 1, 2288 GS Rijswijk, the Netherlands
2StrataSolve Ltd, 42 Gaskell Street, Stockton Heath, Warrington, WA4 2UN, UK
3Shell International Exploration and Production Inc, 200 N. Dairy Ashford, Houston, TX 77079, USA
4Chemostrat Inc., 3760 Westchase Drive, Houston, Texas, TX 77042, USA
Abstract. The Late Cretaceous Epoch was characterized by major global perturbations in the carbon cycle, the most prominent occurring near the Cenomanian–Turonian (CT) transition marked by Oceanic Anoxic Event 2 (OAE-2) at 94.9–93.7 Ma. The Cretaceous Western Interior Seaway (KWIS) was one of several epicontinental seas in which a complex water-mass evolution was recorded in widespread sedimentary successions. This contribution integrates new data on the main components of organic matter, geochemistry, and stable isotopes along a north–south transect from the KWIS to the equatorial western Atlantic and Southern Ocean. In particular, cored sedimentary rocks from the Eagle Ford Group of west Texas (∼ 90–98 Ma) demonstrate subtle temporal and spatial variations in palaeoenvironmental conditions and provide an important geographic constraint for interpreting water-mass evolution. High-latitude (boreal–austral), equatorial Atlantic Tethyan and locally sourced Western Interior Seaway water masses are distinguished by distinct palynological assemblages and geochemical signatures. The northward migration of an equatorial Atlantic Tethyan water mass into the KWIS occurred during the early–middle Cenomanian (98–95 Ma) followed by a major re-organization during the latest Cenomanian–Turonian (95–94 Ma) as a full connection with a northerly boreal water mass was established during peak transgression. This oceanographic change promoted de-stratification of the water column and improved oxygenation throughout the KWIS and as far south as the Demerara Rise off Suriname. In addition, the recorded decline in redox-sensitive trace metals during the onset of OAE-2 likely reflects a genuine oxygenation event related to open water-mass exchange and may have been complicated by variable contribution of organic matter from different sources (e.g. refractory/terrigenous material), requiring further investigation.

Citation: Eldrett, J. S., Dodsworth, P., Bergman, S. C., Wright, M., and Minisini, D.: Water-mass evolution in the Cretaceous Western Interior Seaway of North America and equatorial Atlantic, Clim. Past, 13, 855-878, https://doi.org/10.5194/cp-13-855-2017, 2017.
Publications Copernicus
Download
Short summary
This contribution integrates new data on the main components of organic matter, geochemistry, and stable isotopes for the Cenomanian to Coniacian stages of the Late Cretaceous, along a north–south transect from the Cretaceous Western Interior Seaway to the equatorial western Atlantic and Southern Ocean. Distinct palynological assemblages and geochemical signatures allow insights into palaeoenvironmental conditions and water-mass evolution during this greenhouse climate period.
This contribution integrates new data on the main components of organic matter, geochemistry,...
Share