Oxygen isotope paleotemperatures across the Cretaceous supergreenhouse at southern high latitudes (Naturaliste and Agulhas Plateau)

Author(s): Huber, Brian T.; MacLeod, Kenneth G.; Petruny, Loren; Dickie, Morgan
Author Affiliation(s): Primary:
Smithsonian Institution, Department of Paleobiology, Washington, DC, United States
Other:
University of Missouri, United States
American University, United States
Volume Title: Geological Society of America, 2014 annual meeting & exposition
Source: Abstracts with Programs - Geological Society of America, 46(6), p.274; Geological Society of America, 2014 annual meeting & exposition, Vancouver, BC, Canada, Oct. 19-22, 2014. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: New oxygen isotope paleotemperature estimates from δ8O measurements of well-preserved planktic and benthic foraminifera are presented for the middle Albian of Deep Sea Drilling Project DSDP Site 257 and Turonian through early Campanian of DSDP Site 258 (62-63°S paleolatitude, southeast Indian Ocean) and late Campanian piston core sites on southern Agulhas Plateau (62°S paleolatitude; southwest Indian Ocean). Results are consistent with the long-term planktic and benthic foraminiferal paleotemperature records documented from Falkland Plateau (63°S paleolatitude, southern South Atlantic) and global compilations of deep-sea benthic foraminifera. Assuming mean ocean δw of -1.2 ppm in an ice-free world and standard paleotemperature equation for non-symbiotic foraminifera, southern Indian Ocean middle bathyal δ18O paleotemperatures warmed from 13°C during the middle Albian to a maximum of 19°C during the Turonian, cooled to 14-16°C during the Coniacian- Santonian, and further cooled to 8°C by the late Campanian. Mixed layer planktonic δ18O paleotemperatures parallel the benthic record with maximum warmth of 30°C documented during the Turonian, sustained warmth of between 14 and 16°C from the Coniacian-Santonian and cooling to 8°C by the late Campanian. Extreme warmth during the Turonian-Santonian has been generally attributed to an increase in atmospheric CO2 from volcanic sources in the Caribbean and elsewhere, but how such warm global temperatures were maintained for nearly nine million years is not understood. The timing for termination of the Cretaceous Supergreenhouse interval needs to be better constrained, and the cause for the switch to long-term cooling will also require further investigation.
Year of Publication: 2014
Research Program: DSDP Deep Sea Drilling Project
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Agulhas Plateau; Cretaceous; DSDP Site 257; DSDP Site 258; Deep Sea Drilling Project; Greenhouse effect; Indian Ocean; Isotope ratios; Isotopes; Leg 26; Mesozoic; Naturaliste Plateau; O-18/O-16; Oxygen; Paleoclimatology; Stable isotopes; Wharton Basin
Coordinates: S334742 S334741 E1122826 E1122825
S305910 S305909 E1082100 E1082059
Record ID: 2015026354
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States