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Dinosaur tooth enamel isotopes to study polar palaeohydrology

From: Ben Creisler

A new online paper:

Celina A. Suarez, G. A. Ludvigson, L. A. Gonzalez, A. R. Fiorillo, P.
P. Flaig and P. J. Mccarthy (2013)
Use of multiple oxygen isotope proxies for elucidating Arctic
Cretaceous palaeo-hydrology.
Geological Society Special Publications 382: Isotopic Studies in
Cretaceous Research (advance online publication)
doi: 10.1144/SP382.3

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.