HR: 1340h
AN: V23A-1244    [Abstracts]
TI: Geochemical Evolution of Loess-derived soils Predicted Using a GCM and a Reactive Transport Model
AU: * Williams, J Z
EM: jwilliam@geosc.psu.edu
AF: Department of Geosciences, Center for Environmental Kinetics Analysis, Pennsylvania State University, University Park, PA 16802, United States
AU: * Williams, J Z
EM: jwilliam@geosc.psu.edu
AF: Center for Environmental Kinetics Analysis, Earth and Environmental Institute, Pennsylvania State University, University Park, PA 16802, United States
AU: Pollard, D
EM: pollard@essc.psu.edu
AF: Center for Environmental Kinetics Analysis, Earth and Environmental Institute, Pennsylvania State University, University Park, PA 16802, United States
AU: Godderis, Y
EM: godderis@lmtg.obs-mip.fr
AF: LMTG, CNRS-Observatoire Midi-Pyrenees 14, avenue Edouard Belin, Toulouse, 31400, France
AU: Brantley, S L
EM: brantley@essc.psu.edu
AF: Department of Geosciences, Center for Environmental Kinetics Analysis, Pennsylvania State University, University Park, PA 16802, United States
AU: Brantley, S L
EM: brantley@essc.psu.edu
AF: Center for Environmental Kinetics Analysis, Earth and Environmental Institute, Pennsylvania State University, University Park, PA 16802, United States
AB: A North-South transect along the Mississippi River valley provides an opportune environmental gradient across which to investigate chemical weathering. Soil profiles along this transect are interpreted to have developed from a uniform parent, the Peoria Loess, with pedogenesis commencing between 13 - 10 14C ka BP. At the pedon scale, we examine mineral evolution in these soils based on XRF elemental and mineralogical analysis. To interpret concentration changes as a function of depth and their relation to climate variations along this transect, we simulate climate at specific times during the Holocene using the GENESIS global climate model (GCM). Model outputs of predicted temperatures and moisture fluxes from the GCM are used to drive the WITCH model to calculate chemical weathering as a function of time. The WITCH model describes mineral dissolution/precipitation based on laboratory kinetic rate laws. Additionally, this model calculates soil CO2 levels at varying depths. We compare observed to calculated soil profiles to investigate questions related to how temperature and precipitation drive weathering over the last 13 ka. This is the first example of the use of a GCM to drive a geochemical code to predict soil evolution.
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1039 Alteration and weathering processes (3617)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting