Biogenic Calcic Horizon Development Under Extremely Arid Conditions

Nizzana Sand Dunes, Israel

R. Amit and J.B.J. Harrison

Advances in GeoEcology, 1995, 28, 65-88

Calcic horizons are forming in sandy parent material in the arid environment of the Nizzana sand dunes. In arid environments pedogenic carbonates have been described as Alpha forms which precipitate primarily under physico-chemical processes and are related to the wetting depth and rainfall intensity. However, in the Nizzana sand dunes, biogenic calcium carbonate of the Beta type is occurring under an arid climate.

It was found that the conditions needed for the formation of biogenic calcrete horizons in the study site are parent material with high permeability and intensive biogenic activity including burrows, microorganisms such as fungi and bacteria, and dense vegetation cover. The study demonstrates that depth of carbonate accumulation in an arid environment is not a linear function of precipitation but is initiated by biogenic processes. Surficial soils and paleosols at the study site revealed that at first a biogenic calcite deposition process occurs by fungi and bacteria mainly around roots and burrows, and is then accompanied by physico-chemical deposition as a result of changes in soil permeability.