NEW ADDITIONS TO THE NORTH AMERICAN MID-CRETACEOUS PALEOPRECIPITATION δ18O DATASET: INTEGRATION OF PEDOGENIC CARBONATE AND VERTEBRATE FOSSIL PROXIES

Compilations of δ¹⁸O data from mid-Cretaceous pedogenic siderite (Ufnar et al., 2002, P3 188) and pedogenic calcite (M. Suarez et al., 2011, P3 307) spanning from Colombia to northern Alaska have served as a foundation for exploring mass-balance changes in the hydrologic cycle of the northern hemisphere during the Cretaceous Greenhouse World. Newer siderite δ¹⁸O data from the mid-Cretaceous Nanushuk Fm, and integrated siderite and dinosaur tooth enamel phosphate δ¹⁸O data (C. Suarez et al., 2013, GSL-SP 382) from the Maastrichtian Prince Creek Fm of the Colville Basin in Alaska (> 70° N paleolatitude) lend further credence to the earlier conclusions of Ufnar et al. (2004, GSA Bull 116) that the δ¹⁸O values of Cretaceous Arctic paleoprecipitation were substantially lower than those observed in the modern climate system. Recent investigations in the mid-latitude (34° N) Cedar Mountain Fm of the proximal foreland basin in eastern Utah have integrated δ¹⁸O data from palustrine carbonates (Ludvigson et al., 2010, JSR 80) and vertebrate fossil phosphate (C. Suarez et al., 2013, P3 313; C. Suarez et al., in press to JSR) that show compatible estimates for local paleoprecipitation δ¹⁸O values from pedogenic carbonates, turtle scutes, and crocodilian teeth. Water δ¹⁸O estimates from dinosaurian tooth enamel at the same stratigraphic positions are notably lighter, by from a few up to 16 per mil, and differ among dinosaurian taxa. These results suggest that some dinosaurs ingested water from fluvial discharge from highlands in the Sevier Orogen, possibly including seasonal snowmelt. A new initiative is underway to investigate the δ¹⁸O values of pedogenic carbonates from mid-Cretaceous calcic paleosols of the Wayan (Idaho) and Blackleaf (Montana) fms at 42° N paleolatitude from the leeward rain shadow of the Sevier Orogen. Finally, reports of pedogenic siderites at 25° N paleolatitude from the Cenomanian Tuscaloosa Fm in Mississippi (Ufnar, 2007, Strat. 4) and the Woodbine Fm in east Texas are indicative of humid subtropical environments, and might suggest southward contraction of the Cenomanian Hadley Cell from positions established by earlier Aptian-Albian calcic paleosols. This idea has also been proposed from the distribution of Cretaceous terrestrial paleoenvironments in Asia (Hasegawa et al. 2012, COTP 8).