HR: 14:55h
AN: PP53A-06    [Abstracts]
TI: Climatic and physiological controls on the stable isotope composition of modern and ancient Cupressaceae
AU: * Zinniker, D
EM: david.zinniker@yale.edu
AF: Yale University, Kline Geology Laboratory 210 Whitney Ave., New Haven, CT 06511, United States
AU: Tipple, B
EM: brett.tipple@yale.edu
AF: Yale University, Kline Geology Laboratory 210 Whitney Ave., New Haven, CT 06511, United States
AU: Pagani, M
EM: mark.pagani@yale.edu
AF: Yale University, Kline Geology Laboratory 210 Whitney Ave., New Haven, CT 06511, United States
AB: Unique and abundant secondary metabolites found in waxes and resins of the Callitroid, Cupressoid, and Taxodioid clades of the Cupressaceae family can be identified and quantified in complex mixtures of sedimentary organic compounds. This unusual feature makes it possible to study relatively simple (taxon-specific) isotope systems back in time across the broad array of environments in which these conifers are found. Work on these systems can potentially provide both robust paleoenvironmental proxies (i.e. for source water δD and growing season relative humidity) and quantitative probes into the ecophysiology of these plants in modern and ancient environments. Our research focuses on three genera representing environmental end-members of Cupressaceae - Juniperus, Thuja, and Chamaecyparis - (1) across geographic and environmental gradients in the field, and (2) in specific Holocene and late Pleistocene environmental records. The latter research focuses on peat cores from New England and Oregon and fossil packrat middens from the southwestern United States. Modern transects highlight the sensitivity of Cupressaceae to climatic variables. These include both variables during growth (relative humidity, soil moisture, etc.) and variables affecting seasonal and diurnal growth rates (temperature, winter precipitation, insolation, microhabitat, etc.). Work on ancient records has demonstrated the sensitivity of these unique taxon-specific archives to both subtle and dramatic climate shifts during the Pleistocene and Holocene. This work will result in an improved understanding of climatic and physiological controls on the stable isotopic composition of modern and ancient Cupressaceae - and by extension, other arborescent gymnosperms and C₃ plants - providing a framework for understanding more complexly sourced organic inputs to sediments, coals, and petroleum prior to the advent of C₄ plants. This research also has direct implications for stratigraphic stable isotope studies of gymnosperm markers across the last millenium, the Pleistocene, and important climatic events in the Mesozoic and Tertiary.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1055 Organic and biogenic geochemistry
DE: 1833 Hydroclimatology
DE: 1851 Plant ecology (0476)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting