High latitude meteoric δ 18 O compositions from the Cenomanian Bastion Ridge Formation, Axel Heiberg Island, Canadian Arctic Archipelago: A palaeoclimate proxy from the Sverdrup Basin

• Main Authors: Ross, Jeffrey B., G. A. Ludvigson, C. J. Schröder-Adams, M. B. Suarez
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Geological Society of London 2019
• Subjects: Geology; FOS Earth and related environmental sciences; Arctic; Canadian Arctic Archipelago; Canada; Heiberg; Axel Heiberg Island; Bastion Ridge; Arctic Archipelago; sverdrup basin
• Online Access: https://dx.doi.org/10.6084/m9.figshare.c.4703885.v1; https://geolsoc.figshare.com/collections/High_latitude_meteoric_sup_18_sup_O_compositions_from_the_Cenomanian_Bastion_Ridge_Formation_Axel_Heiberg_Island_Canadian_Arctic_Archipelago_A_palaeoclimate_proxy_from_the_Sverdrup_Basin/4703885/1

Stable isotope analyses of a siderite-cemented siltstone from the Cenomanian Bastion Ridge Formation, Axel Heiberg Island, Canada, produce a range of δ 18 O values of -21.9 to -17 18.4‰ VPDB, and δ 13 C values ranging from 2.0 to 4.4‰ VPDB. A meteoric siderite line of -18.95 ± 0.33‰ VPDB is calculated from siderite cements of the authigenic component. At estimated palaeolatitude of 68-72° N and palaeotemperature range from 12.6 to 13.7°C, the calculated δ 18 O range of palaeoprecipitation is -23.3 to -23.0‰ VSMOW. This result is compatible with other published meteoric water δ 18 O datasets from Cretaceous Arctic studies, but are near the lower end of this range of estimated δ 18 O values. The modern δ 18 O empirical relationship of Dansgaard and Earth System models simulating meteoric δ 18 O values do not yield results for palaeopolar regions that match proxy δ 18 O datasets. Orographic effects of contemporaneous mountain belts, and seasonal biases in groundwater recharge have been proposed to explain this paradox regarding depleted meteoric water δ 18 O values from proxy data in greenhouse worlds. Evidence for local to regional orographic effects and alpine snowmelt biasing groundwater recharge is lacking for the Sverdrup Basin deposits, further indicating that the Dansgaard relationship does not apply to ancient greenhouse worlds.