Use of multiple oxygen isotope proxies for elucidating Arctic Cretaceous palaeo-hydrology

摘要: Stable oxygen isotope analysis of siderite and dinosaur tooth enamel phosphate from the Campanian–Maastrichtian Prince Creek Formation, Alaska, USA, are analysed to determine palaeohydrology ancient Colville Basin north Ancestral Brooks Range. dO freshwater siderites relative V-PDB ranges between 214.86 216.21‰. Dinosaur three different sites (Kikak–Tegoseak, Pediomys Point, Liscomb) range +3.9‰ +10.2.0‰. dOmeteoric water calculated dOsiderite that formed at seasonal temperatures ranging 22 14.5 8C, with a mean annual temperature 6.3 8C. At dOw ranged 222.23 220.89‰ V-SMOW. Ingested compositions estimated teeth assuming body 37 8C local humidity 77.5%, resulting in values 228.7 220.4‰ V-SMOW, suggesting consumption meteoric orographically depleted runoff The compatible two proxies, mutually corroborating evidence extremely O-depleted precipitation high latitudes during Late Cretaceous those generated using general circulation models. This depletion is proposed result increased rainout effects an intensified hydrological cycle, which probably played role sustaining polar warmth. Supplementary material: Parameters used for generation equations compared Kohn (1996) can be found http://www.geolsoc.org.uk/SUP18642 isotopic proxies invaluable tools understanding past current climates. Pedogenic carbonates (siderite calcite) commonly composition (Lohmann 1988; Hays & Grossman 1991; Ludvigson et al. 1998; Ufnar 2004a; Suarez 2011). When over latitudes, gradients global groundwater gradients. gradient related precipitation, itself gradients, and, some instances, orographic effects. Isotopic studies particular importance because future climatic conditions (Kiehl 2011) predicted approach (pCO2, temperature) seen various greenhouse worlds Cretaceous. Several on climate have revealed shallow equatorial-topole air ocean (Wolfe Upchurch 1987; Amiot 2004; Jenkyns Puceat 2007), while others indicated equator-to-pole steeper than modern system (Ludvigson 2002; steep has been explained as rainout, thereby increasing latent heat transport equator poles (Ufnar 2004b). These conclusions based empirical From: Bojar, A.-V., Melinte-Dobrinescu, M. C. Smit, J. (eds) Studies Research. Geological Society, London, Special Publications, 382, http://dx.doi.org/10.1144/SP382.3 # Society London 2013. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics by guest June 17, 2013 http://sp.lyellcollection.org/ Downloaded