HR: 0800h
AN: PP41A-0576    [Abstracts]
TI: Mineral Surface Control of Organic Carbon Burial: Secular Rise of Clay Mineral Deposition in the Precambrian and the Rise of Oxygen
AU: * Kennedy, M J
EM: martink@mail.ucr.edu
AF: University of California, Riverside, Department of Earth Science, University of California Riverside, Riverside, CA 92521 United States
AU: Droser, M L
EM: mary.droser@ucr.edu
AF: University of California, Riverside, Department of Earth Science, University of California Riverside, Riverside, CA 92521 United States
AU: Mayer, L
EM: lmayer@maine.edu
AF: Darling Marine Center, University of Maine, Wapole, ME 04573 United States
AU: Pevear, D
EM: p00bare@pdq.net
AF: University of California, Riverside, Department of Earth Science, University of California Riverside, Riverside, CA 92521 United States
AB: Accumulation of oxygen in the earth's atmosphere requires burial of organic matter in marine sediments. Today, the major mode of organic carbon burial is in association with detrital pedogenic clay minerals which serve to protect organic matter against biological oxidation during burial in marine sediments. The bulk of detrital clays that are ultimately deposited in marine sediments are formed in biologically active soils that require plant processes to retain water, concentrate weathering produced solutes, stablize soils, and provide an adsorptive media. At some point in Earth history before the colonization of land surfaces by plants and the formation of biotic soils, clay mineral surface limitation may have severely reduced the preservation potential of organic carbon during burial. An important consequence of this would have also been a reduced flux of oxygen to the atmosphere because organic carbon and oxygen release are coupled. Multiple independent lines of evidence indicate a significant change in continental weathering and pedogenic clay mineral formation and establishment of the `clay factory' that coincides with colonization of land surfaces by primitive plant like organisms in the late Precambrian. The enhanced burial efficiency that would have accompanied the shift to the modern mode of detrital pedogenic clay hosted carbon burial would have driven an increase in oxygen levels toward present values. Evidence suggests that this rise in oxygen occurred just prior to the advent of the first complex animals in the Ediacaran.
DE: 0400 Biogeosciences
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting