Program
Earth and Planetary Sciences
College
Arts and Sciences
Student Level
Master's
Start Date
7-11-2018 3:00 PM
End Date
7-11-2018 4:00 PM
Abstract
The Western Interior Seaway (WIS) was a North American epicontinental sea that was connected to the open ocean through the passage of the northern Boreal Sea and the southern Tethys Sea from the early Albian (~113 million years ago) to the early Paleogene (~65 million years ago). The WIS began to recced and lost its connection to the southern Tethys Sea in the late Campanian (~72 million years ago). In the early Paleogene, the WIS dried up completely. The oxygen isotopic composition (δ18O) of benthic bivalves was measured from the upper Campanian and lower Maastrichtian (75 million years ago to 69 million years ago) to decipher if the WIS had different δ18O values than the δ18O values of the open ocean. This study would begin to answer the question if the δ18O values of the WIS changed over time since the WIS began to retreat from the open ocean in the late Campanian. We measured δ18O of a variety of well-preserved epifaunal (Anisomyon, Endocostea, Inoceramus, Ostrea, and Pteria) and infaunal (Cucullaea, Cymbophora, Geltena, Lucina, Nucula, and Tenuiptera) bivalves. Then, we compared the δ18O values of the WIS benthic bivalves to a literature search conducted on the δ18O values of WIS bivalves and ammonites and δ18O values of the open ocean foraminifera, bivalves, and ammonites. Most WIS δ18O values range from -6‰ to 0‰ and these δ18O values overlap with the open ocean studies, which range from -5‰ to +2‰. The δ18O values of the WIS are not significantly different than the δ18O values of the open ocean even though the WIS began to lose its connection to the open ocean. However, the WIS does has lower δ18O values than the open ocean and this could possibly be due to freshwater input to the WIS or increased evaporation in the WIS. This systematically collected dataset of bivalve δ18O values may contribute to Late Cretaceous climate models and paleoecological and paleoenvironmental studies.
Included in
Biogeochemistry Commons, Geochemistry Commons, Inorganic Chemistry Commons, Paleobiology Commons, Paleontology Commons
Are the Oxygen Isotope Values of the Late Cretaceous Western Interior Seaway Different from the Open Ocean?
The Western Interior Seaway (WIS) was a North American epicontinental sea that was connected to the open ocean through the passage of the northern Boreal Sea and the southern Tethys Sea from the early Albian (~113 million years ago) to the early Paleogene (~65 million years ago). The WIS began to recced and lost its connection to the southern Tethys Sea in the late Campanian (~72 million years ago). In the early Paleogene, the WIS dried up completely. The oxygen isotopic composition (δ18O) of benthic bivalves was measured from the upper Campanian and lower Maastrichtian (75 million years ago to 69 million years ago) to decipher if the WIS had different δ18O values than the δ18O values of the open ocean. This study would begin to answer the question if the δ18O values of the WIS changed over time since the WIS began to retreat from the open ocean in the late Campanian. We measured δ18O of a variety of well-preserved epifaunal (Anisomyon, Endocostea, Inoceramus, Ostrea, and Pteria) and infaunal (Cucullaea, Cymbophora, Geltena, Lucina, Nucula, and Tenuiptera) bivalves. Then, we compared the δ18O values of the WIS benthic bivalves to a literature search conducted on the δ18O values of WIS bivalves and ammonites and δ18O values of the open ocean foraminifera, bivalves, and ammonites. Most WIS δ18O values range from -6‰ to 0‰ and these δ18O values overlap with the open ocean studies, which range from -5‰ to +2‰. The δ18O values of the WIS are not significantly different than the δ18O values of the open ocean even though the WIS began to lose its connection to the open ocean. However, the WIS does has lower δ18O values than the open ocean and this could possibly be due to freshwater input to the WIS or increased evaporation in the WIS. This systematically collected dataset of bivalve δ18O values may contribute to Late Cretaceous climate models and paleoecological and paleoenvironmental studies.
