Early Maastrichtian carbon cycle perturbation and cooling event; implications from the South Atlantic Ocean

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doi: 10.1029/2008PA001654
Author(s): Friedrich, Oliver; Herrle, Jens O.; Wilson, Paul A.; Cooper, Matthew J.; Erbacher, Jochen; Hemleben, Christoph
Author Affiliation(s): Primary:
Universität Tübingen, Institut für Geowissenschaften, Tubingen, Federal Republic of Germany
Other:
University of Alberta, Canada
University of Southampton, United Kingdom
Bundesanstalt für Geowissenschaften und Rohstoffe, Federal Republic of Germany
Volume Title: Paleoceanography
Source: Paleoceanography, 24(2). Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 83 refs.; illus.
Summary: Published stable isotope records in marine carbonate are characterized by a positive δ18O excursion associated with a negative δ13C shift during the early Maastrichtian. However, the cause and even the precise timing of these excursions remain uncertain. We have generated high-resolution foraminiferal stable isotope and gray-scale records for the latest Campanian to early Maastrichtian (∼73-68 Ma) at two Ocean Drilling Program sites, 525 (Walvis Ridge) and 690 (Weddell Sea). We demonstrate that the negative δ13C excursion is decoupled from the δ18O increase with a lag of about 600 ka. Our δ13C records (both planktic and benthic) show an amplitude for the negative excursion of 0.7ppm that falls between about 72.1 and 70.7 Ma. Our planktic δ18O records indicate an overall increase of 1.2ppm from 73 to 68 Ma at Site 690, whereas at Site 525 they record a slightly smaller increase (∼1ppm) that peaks around 70.1 Ma with decreasing values thereafter. Our benthic δ18O data indicate an increase of ∼1.5ppm at Site 525 and ∼0.7ppm at Site 690 between about 71.4 and 69.9 Ma. Benthic δ18O values show different baseline values at the two sites before and after the excursion, but the larger increase at Site 525 means that the values attained at the peak of the excursion are similar at the two sites. We interpret this observation in terms of water mass changes. The excursion is interpreted to reflect a cooling of bottom waters in response to the strengthening contribution of intermediate- to deep-water production in the high southern latitudes rather than increased ice volume. The associated carbon cycle perturbations that we observe are interpreted to reflect a weakening of surface water stratification and increased productivity, as supported by our gray value data.
Year of Publication: 2009
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; C-13/C-12; Carbon; Carbon cycle; Chemostratigraphy; Cretaceous; DSDP Site 525; Deep Sea Drilling Project; Foraminifera; Geochemical cycle; IPOD; Ice; Invertebrata; Isotope ratios; Isotopes; Leg 113; Leg 74; Lower Maestrichtian; Maestrichtian; Marine environment; Maud Rise; Mesozoic; Microfossils; O-18/O-16; ODP Site 690; Ocean Drilling Program; Oxygen; Paleo-oceanography; Paleoclimatology; Paleoenvironment; Protista; Senonian; South Atlantic; Southern Ocean; Stable isotopes; Upper Cretaceous; Walvis Ridge; Weddell Sea
Coordinates: S650938 S650937 E0011218 E0011218
S290415 S290414 E0025908 E0025907
Record ID: 2010081644
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