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Marked Decline in Atmospheric Carbon Dioxide Concentrations During the Paleogene
Stable carbon isotopic values of di-unsaturated alkenones extracted from deep sea cores are used to reconstruct pCO2 from the middle Eocene to the late Oligocene and demonstrate that it ranged between 1000 to 1500 parts per million by volume in the middle to late Eocene, then decreased in several steps during theOligocene, and reached modern levels by the latest Oligaen.
Molecular Paleohydrology: Interpreting the Hydrogen-Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms
The factors and processes that are known to influence the hydrogen-isotopic compositions of lipids-especially n-alkanes-from photosynthesizing organisms are reviewed, and a framework for interpreting their D/H ratios from ancient sediments is provided to identify future research opportunities.
Global patterns in leaf 13C discrimination and implications for studies of past and future climate
A 4.6‰ decline in the δ13C of atmospheric CO2 is estimated at the onset of the Paleocene-Eocene Thermal Maximum, an abrupt global warming event ∼55.8 Ma, leading to better constraints on past greenhouse-gas perturbations.
New insights into Archean sulfur cycle from mass-independent sulfur isotope records from the Hamersley Basin, Australia
We have measured multiple sulfur isotope ratios ( 34 S/ 33 S/ 32 S) for sulfide sulfur in shale and carbonate lithofacies from the Hamersley Basin, Western Australia. The v 33 S values (v 33 SWN 33
Influence of physiology and climate on δD of leaf wax n-alkanes from C3 and C4 grasses
Abstract We measured hydrogen isotope compositions (δD) of high-molecular-weight n-alkanes (C27–C33) from grasses grown in greenhouses and collected from the US Great Plains. In both cases, n-alkanes
Miocene evolution of atmospheric carbon dioxide
Changes in pCO2 or ocean circulation are generally invoked to explain warm early Miocene climates and a rapid East Antarctic ice sheet (EAIS) expansion in the middle Miocene. This study reconstructs
Transient Floral Change and Rapid Global Warming at the Paleocene-Eocene Boundary
Floral response to warming and/or increased atmospheric CO2 during the PETM was comparable in rate and magnitude to that seen in postglacial floras and to the predicted effects of anthropogenic carbon release and climate change on future vegetation.
Fractionation of carbon isotopes by phytoplankton and estimates of ancient CO2 levels.
Reports of the 13C content of marine particulate organic carbon are compiled and on the basis of GEOSECS data and temperatures, concentrations, and isotopic compositions of dissolved CO2 in the
Late Archean rise of aerobic microbial ecosystems
  • J. Eigenbrode, K. Freeman
  • Environmental Science, Medicine
    Proceedings of the National Academy of Sciences
  • 24 October 2006
The data suggest that a global-scale expansion of oxygenated habitats accompanied the progression away from anaerobic ecosystems toward respiring microbial communities fueled by oxygenic photosynthesis before the oxygenation of the atmosphere after 2.45 billion years ago.
Consistent fractionation of 13C in nature and in the laboratory: growth-rate effects in some haptophyte algae.
Before concentrations of dissolved CO2 can be estimated from isotopic fractionations, some means of accounting for variations in growth rate must be found, perhaps by drawing on relationships between [PO4] and Cd/Ca ratios in shells of planktonic foraminifera.