Meyers, Stephen Richard and Sageman, Bradley (2004): Cenomanian/Turonian orbital chronologies and burial flux estimates; calibrating the biogeochemical reconstruction of oceanic anoxic event II

Leg/Site/Hole:
Identifier:
2005-059862
georefid

Creator:
Meyers, Stephen Richard
Yale University, Department of Geology and Geophysics, New Haven, CT, United States
author

Sageman, Bradley
Northwestern University, United States
author

Identification:
Cenomanian/Turonian orbital chronologies and burial flux estimates; calibrating the biogeochemical reconstruction of oceanic anoxic event II
2004
In: Anonymous, Geological Society of America, 2004 annual meeting
Geological Society of America (GSA), Boulder, CO, United States
36
5
198
The calculation of geochemical proxy fluxes and rates of biotic change are critical components of integrated biogeochemical studies of the Earth System. Such estimates provide a decisive tool for interpretation of the causes and consequences of biogeochemical perturbations associated with critical intervals of environmental/oceanographic change. Sufficient time control to constrain these estimates for short-term (<1 Ma) biogeochemical events has largely been limited to the Tertiary. In recent years, however, quantification of Milankovitch orbital cyclicity within strata that record major oceanographic events has made it possible to extend high-resolution burial flux estimates as far back as the Mid-Cretaceous. Unfortunately, orbital reconstructions for the same event may vary depending on geographic location, making a global synthesis of temporally constrained biogeochemical data difficult. In this talk we present a new methodology for the quantitative identification and integration of orbital time scales from geographically distant rhythmic sequences. We demonstrate the method with examples from the Cenomanian/Turonian (C/T) Oceanic Anoxic Event II (OAE II), hypothesized to be a global episode of enhanced organic matter burial and oceanographic change. Published orbital timescales for OAE II range from approximately 320 kyr to approximately 960 kyr. With our new method, which calculates a misfit parameter between observed and predicted bedding frequencies across a range of sedimentation rates, we are able to identify the best-fit sedimentation rate for a given section. Application of the method to C/T sections from the U.S. Western Interior, Atlantic ODP/DSDP sites, Europe, and the Tarfaya Basin allows a quantitative assessment of each orbital record, and construction of a globally coherent C/T time scale. The globally integrated time scale provides an opportunity to assess burial fluxes of organic matter, carbonate, and other constituents at different sites during OAE II, and thus evaluate the relative role of geographically distinct depositional settings on perturbations of the global carbon cycle.
English
Coverage:Geographic coordinates:
North:84.0000
West:-173.0000East: 75.0000
South:8.0000

Stratigraphy; anaerobic environment; biochemistry; biota; calibration; carbon; carbon cycle; Cenomanian; Cretaceous; Deep Sea Drilling Project; Europe; geochemical cycle; geochemistry; global; interpretation; Mesozoic; Milankovitch theory; North America; Ocean Drilling Program; organic compounds; paleo-oceanography; paleoenvironment; quantitative analysis; rates; reconstruction; sedimentation; sedimentation rates; Tarfaya Basin; time scales; Turonian; United States; Upper Cretaceous; variations; Western Interior;

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