Exploring the Deuterium Excess of Cretaceous Arctic Paleoprecipitation Using Stable Isotope Composition of Clay Minerals from the Prince Creek Formation (Maastrichtian) in Northern Alaska

• Published in: Geosciences
• Main Authors: Kate Andrzejewski, Greg Ludvigson, Marina Suarez, Paul McCarthy, Peter Flaig
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2023
• Subjects: Cretaceous; hydrogen and oxygen isotopes; paleoprecipitation; pedogenic phyllosilicates; Geology; QE1-996.5; Arctic; Alaska
• Online Access: https://doi.org/10.3390/geosciences13090273; https://doaj.org/article/6f0fc397d03f4aacac705988a09d3caa

We report estimated stable isotope compositions of Artic paleoprecipitation using phyllosilicates sampled from three paleosols and two bentonites in the Prince Creek Formation (Maastrichtian) in northern Alaska. Previous studies reported a deuterium excess in estimates of Arctic paleoprecipitation from the Late Cretaceous by combining hydrogen and oxygen proxy sources, including pedogenic minerals, dinosaurian tooth enamel phosphates, pedogenic siderites, and n-alkane biomarkers. The new dataset produced in this study removes uncertainty on possible explanations (photosynthetic and transpiration) of the deuterium excess by producing stable hydrogen and oxygen isotopic signatures from the same source material. The δD of the phyllosilicates range from −171‰ to −72‰ VSMOW and δ 18 O ranges from 5.0 to 11.8‰ VSMOW. By assuming a MAT of 6.3 °C and calculating uniquely derived fractionation equations for each phyllosilicate, we report estimated isotopic composition of Late Cretaceous paleoprecipitation with an average δD value of −133‰ VSMOW, corresponding to an average δ 18 O value of −20.3‰ VSMOW. The estimates of Late Cretaceous paleoprecipitation do not intersect the Global Meteoric Water Line and reveal a reported deuterium excess ranging from 7 to 46 per mil. These results confirm the presence of a deuterium excess in Late Cretaceous Arctic paleoprecipitation and provide new insight to assessing possible explanations for this phenomenon.