Time evolution of the mineralogical composition of Mississippi Valley loess over the last 10kyr

Climate and geochemical modeling

Yves Goddéris, Jennifer Zan Williams, Jacques Schott, David Pollard, Susan Louise Brantley

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

Anthropogenic and natural climate change affect processes in the atmosphere, biosphere, hydrosphere, and pedosphere. The impact of climate on soil evolution has not been well-explored, largely due to slow rates and the complexity of coupled processes that must be observed and simulated. The rates of mineral weathering in loess deposited 23kyr ago and experiencing soil formation for 13kyr are explored here using the WITCH model for weathering and the GENESIS model for climate simulation. The WITCH model, which uses rigorous kinetic parameters and laws with provision for the effect on rates of deviation from equilibrium, can successfully simulate the depletion profiles in the soil for dolomite and albite if soil CO2 is assumed to rise over the last 10kyr up to about 30-40× the present atmospheric pressure, and if the solubility product of the Ca-smectite is assumed equal to that of an Fe(III)-rich Ca-montmorillonite. Such simulations document that dissolution behavior for silicates and carbonates are strongly coupled through pH, and for Ca-smectite and feldspars through dissolved silica. Such coupling is not incorporated in simple geometric and analytical models describing mineral dissolution, and therefore probably contributes to the long-standing observation of discrepancies among laboratory and field mineral dissolution rates.

Original languageEnglish (US)
Pages (from-to)6357-6374
Number of pages18
JournalGeochimica et Cosmochimica Acta
Volume74
Issue number22
DOIs
StatePublished - Nov 15 2010

Fingerprint

loess
Minerals
Soils
valley
Dissolution
dissolution
climate
Weathering
Chemical analysis
smectite
modeling
mineral
Hydrosphere
weathering
Bentonite
Silicates
hydrosphere
Earth atmosphere
soil
Carbonates

All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology

Cite this

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title = "Time evolution of the mineralogical composition of Mississippi Valley loess over the last 10kyr: Climate and geochemical modeling",
abstract = "Anthropogenic and natural climate change affect processes in the atmosphere, biosphere, hydrosphere, and pedosphere. The impact of climate on soil evolution has not been well-explored, largely due to slow rates and the complexity of coupled processes that must be observed and simulated. The rates of mineral weathering in loess deposited 23kyr ago and experiencing soil formation for 13kyr are explored here using the WITCH model for weathering and the GENESIS model for climate simulation. The WITCH model, which uses rigorous kinetic parameters and laws with provision for the effect on rates of deviation from equilibrium, can successfully simulate the depletion profiles in the soil for dolomite and albite if soil CO2 is assumed to rise over the last 10kyr up to about 30-40× the present atmospheric pressure, and if the solubility product of the Ca-smectite is assumed equal to that of an Fe(III)-rich Ca-montmorillonite. Such simulations document that dissolution behavior for silicates and carbonates are strongly coupled through pH, and for Ca-smectite and feldspars through dissolved silica. Such coupling is not incorporated in simple geometric and analytical models describing mineral dissolution, and therefore probably contributes to the long-standing observation of discrepancies among laboratory and field mineral dissolution rates.",
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Time evolution of the mineralogical composition of Mississippi Valley loess over the last 10kyr : Climate and geochemical modeling. / Goddéris, Yves; Williams, Jennifer Zan; Schott, Jacques; Pollard, David; Brantley, Susan Louise.

In: Geochimica et Cosmochimica Acta, Vol. 74, No. 22, 15.11.2010, p. 6357-6374.

Research output: Contribution to journalArticle

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AU - Schott, Jacques

AU - Pollard, David

AU - Brantley, Susan Louise

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