Prelude to the Turonian thermal maximum; Cenomanian foraminiferal oxygen isotope temperature records from southern high latitudes

Author(s): Huber, Brian T.; MacLeod, Kenneth G.; Goughnour, Rebecca
International Ocean Discovery Program, Expedition 369 Scientists
Author Affiliation(s): Primary:
Smithsonian Institution National Museum of Natural History, Department of Paleobiology, Washington, DC, United States
University of Missouri at Columbia, United States
Adrian College, United States
Volume Title: Geological Society of America, 2018 annual meeting & exposition
Source: Abstracts with Programs - Geological Society of America, 50(6); Geological Society of America, 2018 annual meeting & exposition, Indianapolis, IN, Nov. 4-7, 2018. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: The evolution of Cenomanian marine temperatures leading up to the Turonian Thermal Maximum has not been adequately characterized because reliable δ18O data are few especially at high latitudes. Ocean drilling at IODP Sites U1513, U1514, and U1516 in the Mentelle Basin (SE Indian Ocean) recovered a nearly complete late Albian-Cenomanian sediment record deposited at 60°S paleolatitude. Analyses of samples from these cores will improve knowledge of the pre-Turonian austral marine paleotemperature history. Mid- to upper Cenomanian cores from all three sites yield moderately to well-preserved foraminifera with planktic:benthic ratios varying from 70-90%. Benthic foraminifera within this time interval include a relatively diverse assemblage of calcareous and agglutinated species that indicate deposition at bathyal paleodepths. Planktonic assemblages in this interval are small in size and low in diversity, and species used to identify tropical biozones are absent from most samples. Down-core from the lower Cenomanian to upper Albian, foraminiferal assemblages are increasingly dominated by agglutinated species and planktic:benthic ratios vary between 0-50%. Using standard assumptions for the isotopic composition of Cretaceous seawater, preliminary oxygen isotope records from mid- late Cenomanian calcareous benthic taxa indicate warm high latitude temperatures with bottom waters mostly ranging between 14-16°C and surface waters mostly between 19-22°C. Although these oxygen isotope temperature estimates indicate hot greenhouse conditions at southern high latitudes during the Cenomanian, the planktic δ18O values are still more than 1 ppm higher (>4°C cooler) than planktic values obtained from Turonian samples from DSDP Site 258, a site that was drilled previously at the IODP Site U1513 location. Additional foraminiferal stable isotope analyses of Mid-Cretaceous foraminifera from these sites will provide new insight and better resolution on the paleoclimatic and paleoceanographic conditions prior to widespread organic carbon burial during Oceanic Anoxic Event 2 and the subsequent Turonian Thermal Maximum.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
IODP2 International Ocean Discovery Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Albian; Cenomanian; Cretaceous; Expedition 369; Foraminifera; IODP Site U1513; IODP Site U1514; IODP Site U1516; Indian Ocean; International Ocean Discovery Program; Isotope ratios; Isotopes; Lower Cretaceous; Marine environment; Mentelle Basin; Mesozoic; Microfossils; O-18/O-16; Oxygen; Paleoclimatology; Paleoenvironment; Paleotemperature; Stable isotopes; Upper Cretaceous
Coordinates: S342055 S330714 E1130529 E1124758
Record ID: 2019023718
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States