Terrestrial Paleoclimatology of the Early Cretaceous Western Interior Foreland Basin of North America

Abstract

A north-south trending foreland basin that extended from the Boreal to Tethyan realms, the Western Interior Basin (WIB) encompassed zonal climatic belts including the subtropical Hadley Cell (northern boundary near 30 °N palolatitude), the mid-latitude Ferrel Cell (northern boundary near 60 °N paleolatitude), and the high-latitude Polar Cell. The zonal belts exerted strong influence on climatically-sensitive terrestrial deposits, including calcic mudstone paleosols in the Hadley Cell, contrasted with coals and sideritic mudstone paleosols in the Ferrel and Polar cells. North-south transects of the δ18O values of pedogenic carbonates (calcic and sideritic) in the WIB have been used to constrain oxygen isotope mass balance models of the mid-Cretaceous hydrologic cycle, and indicate substantial increases in both global and zonal precipitation rates over that of the modern climate system. During sea-level highstands of the mid-Cretaceous, a throughgoing Western Interior Seaway connected Boreal and Tethyan seas in the central United States beginning in the late Albian. The antiquity of Early Cretaceous terrestrial deposits filling the WIB in the central United States is still subject to question, although data suggesting the presence of Neocomian units are starting to emerge. Published terrestrial records of Aptian-Albian Carbon Isotope Excursions (CIEs) generally associated with the Cretaceous Oceanic Anoxic Events 1a, 1b, and 1d show that these global-scale carbon cycle perturbations can be reliably traced into continental deposits. The sedimentologic characters of terrestrial units spanning these CIEs clearly show evidence for major paleoclimatic impacts on land. Pedogenic carbonate pCO₂ time series constructed from Aptian-Albian paleosols in the WIB (Ludvigson et al., 2015, Cret. Res. 56:1-24) and in China (Li et al., 2014, Geol. Mag. 151:830-849) both show an overall long-term fall through the Aptian-Albian interval punctuated by abrupt changes, with peak values near the Aptian-Albian boundary that are temporally associated with OAE 1b.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016