Sheldon,N.D. and Tabor,N.J.(2009): Quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols. Earth-Science Reviews, 95, 1-52.


 Paleosols (fossil soils) are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows. Until recently, paleosols were studied using primarily qualitative methods. In recent years, paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor. Some of this change has been a result of applying existing techniques to new materials, but many of the innovations have been the result of applying new techniques to new materials, including thermodynamic modeling of soil formation, isotope geochemistry, and applications of empirical relationships derived from modern soils. A variety of semi-quantitative and quantitative tools has been developed to examine past weathering and pedogenesis, and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed. Though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions, proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils from at the Earth's surface, in direct contact with the atmospheric and climatic conditions at the time of their formation. Paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance, weathering intensity, mean annual precipitation and temperature during pedogenesis, nutrient fluxes into and out of the paleosols, the atmospheric composition of important gases including CO2 and O2, the moisture balance during pedogenesis, the soil gas composition, reconstructed vegetative covering, and paleo-altitude.

Keywords: paleosols; paleoclimate; paleoenvironments; isotopes; geochemistry; pedogenesis』

1. Introduction
2. Qualitative methods
 2.1. Taxonomic and stratigraphic approaches
 2.2. Semi-quantitative methods
  2.2.1. Compaction
  2.2.2. Ichnology
3. Quantitative methods overview
4. Clay mineralogy of soils and paleosols
 4.1. Occurrence of clay minerals
5. Whole rock geochemistry
 5.1. Analytical methods
 5.2. Provenance and pedogenesis
  5.2.1. Major element ratios and pedogenic processes
  5.2.2. Major element weathering indices
  5.2.3. Trace element ratios
  5.2.4. Rare earth elements
 5.3. Mass-balance calculations
  5.3.1. Pedogenesis and diagenesis
  5.3.2. Precambrian atmospheric CO2 from mass balance
 5.4. Paleotemperature
 5.5. Paleoprecipitation
  5.5.1. Content of Fe-Mn nodules in vertisols
  5.5.2. Depth to Bk horizon
  5.5.3. Bw/Bt horizon geochemistry
 5.6. Long-term chemical weathering
6. Thermodynamic approaches
 6.1. Simple versus complex systems
 6.2. Single-equation approaches
  6.2.1. Precambrian atmospheric CO2
  6.2.2. Earliest Triassic soil formation
 6.3. Multiple-equation approaches
7. Stable isotope approaches
 7.1. Stable isotopic composition of pedogenic minerals as paleoenvironmental proxies
  7.1.1. Mineral-water isotope fractionation and the jargon of stable isotope geochemistry
  7.1.2. Stable isotope fractionation factors of common pedogenic minerals
  7.1.3. Relationship between hydrogen and oxygen isotopes in continental waters
 7.2. Carbon in soils
  7.2.1. One-component soil CO2
  7.2.2. Two-component soil CO2
  7.2.3. Three-component soil CO2
 7.3. Soil and paleosol carbonate
  7.3.1. Pedogenic calcite δ18O values Pedogenic calcite as a proxy for soil moisture δ18O values Pedogenic calcite δ18O values as a proxy of paleotemperature
  7.3.2. Pedogenic siderite as a proxy for soil moisture δ18O values
 7.4. δ13C values of carbonate
  7.4.1. Calcite from one-component of soil CO2
  7.4.2. δ13C of pedogenic siderite
  7.4.3. Calcite derived from 2-component soil CO2 mixing Estimates of paleoatmospheric pCO2 Soil calcite δ13C as a means of assessing soil pCO2 and productivity Pedogenic goethite
  7.4.4. Soil carbonates formed by mixing of three-components of soil CO2 Calcite Goethite
 7.5. δ18O and δD of hydroxylated minerals
  7.5.1. Origin of residual deposits
  7.5.2. Variations in soil moisture δ18O and δD values
  7.5.3. Single-mineral paleotemperature estimates Goethite Smectite and mixed phyllosilicates Kaolinite
  7.5.4. Mineral-pair δ18O values
 7.6. Paleo-vegetation/paleo-photosynthesis
8. Future approaches and challenges
 8.1. Boron isotopes
 8.2. Energy balance models
 8.3. “Clumped isotope” paleothermometry
9. Summary
Appendix A. Supplementary data