2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 53-12
Presentation Time: 4:15 PM


IBARRA, Daniel E.1, JONES, Matthew M.2, GRAHAM, Stephan A.3, SAGEMAN, Bradley B.4 and CHAMBERLAIN, C. Page1, (1)Earth System Science, Stanford University, 473 Via Ortega, Rm 140, Stanford, CA 94305, (2)Earth and Planetary Sciences, Northwestern University, 2145 Sheridan Road, Technological Institute, Rm. F374, Evanston, IL 60202, (3)Department of Geological Sciences, Stanford University, 450 Serra Mall, Bldg. 320, Stanford, CA 94305-2115, (4)Earth and Planetary Sciences, Northwestern University, 2145 Sheridan Rd, Evanston, IL 60208, danieli@stanford.edu

The terrestrial response to carbon cycle perturbations during the Cretaceous is largely undetermined. However, the Songliao Basin (northeast China) preserves the record of a long-lived lake system allowing investigation of mid-latitude terrestrial responses to major ocean-climate perturbations, such as the Cretaceous Oceanic Anoxic Events (OAEs). A major challenge in evaluating synchronous environmental change between marine and terrestrial realms is chronostratigraphic uncertainty due to limited biostratigraphic control. Recently published astrochronologies and U-Pb age determinations reduce age uncertainty for the Late Cretaceous Qingshankou and Yaojia Formations, and permit preliminary interpretation of chemostratigraphic data from the Songliao Basin in a global context. In this study we investigate the terrestrial response and hydrologic evolution of the Songliao Basin system during the OAE 3 interval (~88 to 86.5 Ma) from the SK-1 (S) core by: (1) modeling oxygen isotope and trace element variations in ostracod valves; and (2) presenting a new δ13C record from lacustrine organic matter to compare to the existing ostracod δ13C record and marine δ13C records. The modeling approach uses a system of total differential equations describing variations in measured δ18O, Sr/Ca, and Mg/Ca as a function of temperature, runoff and evaporation for a terminally draining lake system. The ostracod valve δ13C record exhibits a broad ~+2.5 ‰ excursion, hypothesized to define OAE 3, followed by a sharp ~-4 ‰ decrease. During and after the putative OAE 3 we find two warming events of 3 to 5°C accompanied by sustained ~10% increase in lake size over the interval. Previous workers have suggested that OAE 3 was limited to the Western Hemisphere; however, our modeling and chemostratigraphic data suggest that OAE 3 is recorded in the Songliao Basin. Preliminary comparison of astronomically tuned δ13C curves from the Western Interior Basin and astronomically tuned OAE 3 ostracod δ13C data in the Songliao Basin indicates a 0.5 to 1 Myr lag in the peak δ13C excursion and warming in the Songliao Basin. Future work comparing existing ostracod and new organic matter δ13C records will provide further information linking Songliao Basin to the Northern Hemisphere response to the OAE 3 carbon cycle perturbation.