Use of multiple oxygen isotope proxies for elucidating Arctic Cretaceous palaeo-hydrology
Celina A. Suarez, G. A. Ludvigson, L. A. Gonzalez, A. R. Fiorillo, P. P. Flaig, P. J. McCarthy, 2013. "Use of multiple oxygen isotope proxies for elucidating Arctic Cretaceous palaeo-hydrology", Isotopic Studies in Cretaceous Research, A.-V. Bojar, M. C. Melinte-Dobrinescu, J. Smit
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Stable oxygen isotope analysis of siderite and dinosaur tooth enamel phosphate from the Campanian–Maastrichtian Prince Creek Formation, Alaska, USA, are analysed to determine the palaeohydrology of the ancient Colville Basin north of the Ancestral Brooks Range. δ18O of freshwater siderites relative to V-PDB ranges between −14.86 and −16.21‰. Dinosaur tooth enamel δ18O from three different sites (Kikak–Tegoseak, Pediomys Point, Liscomb) range between +3.9‰ and +10.2.0‰. δ18Ometeoric water are calculated from δ18Osiderite that formed at seasonal temperatures ranging from −2 to 14.5 °C, with a mean annual temperature of 6.3 °C. At 6.3 °C, the δ18Ow calculated from siderite ranged between −22.23 and −20.89‰ V-SMOW. Ingested water compositions are estimated from dinosaur teeth assuming body temperatures of 37 °C and local relative humidity of 77.5%, resulting in values ranging from −28.7 to −20.4‰ V-SMOW, suggesting consumption of meteoric water and orographically depleted runoff from the Brooks Range. The ranges in calculated δ18Ometeoric water are compatible between the two proxies, and are mutually corroborating evidence of extremely 18O-depleted precipitation at high latitudes during the Late Cretaceous relative to those generated using general circulation models. This depletion is proposed to result from increased rainout effects from an intensified hydrological cycle, which probably played a role in sustaining polar warmth.
Parameters used for generation of equations compared to Kohn (1996) can be found at http://www.geolsoc.org.uk/SUP18642
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Isotopic Studies in Cretaceous Research
The Cretaceous was a period characterized by very warm climate, oceanic anoxic and oxic events and enhanced volcanic activity. The end of the Cretaceous is punctuated by a well-documented asteroid impact and the extinction of, among other groups, the dinosaurs. This volume elucidates various aspects of Cretaceous marine and continental environmental conditions. The articles in this book present a broad range of interdisciplinary contributions, which are grouped into sections on marine environments(including anoxic and oxic events, volcanism and the Cretaceous–Palaeocene boundary); mixed marine–freshwater environments and continental records. The isotopic data are combined with further geochemical, palaeontological, lithological and mineralogical proxies. The interdisciplinary approach offered here gives a solid investigation base for this fascinating period. There are examples from Europe, Asia, South and North America, and from the Early Cretaceous to the Cretaceous–Paleogene boundary.