Climatic Control of the Geography of Clay Minerals Genesis

Abstract

Concentrations of secondary clay minerals (mica, vermiculite, montmorillonite, chlorite, and kaolinite) in the A horizon of 99 U.S. soils were used in a stepwise regression with climate, parent material, and soil property variables to develop models of the occurrence and abundance of each clay mineral species. Climate-especially water balance estimates of soil water surplus, water deficit, and indicators of seasonality-were especially useful variables. These models correctly predicted the dominant (most abundant) clay minerals for 80 of the 99 sites even though the RZ values for individual clays were modest. Maps of predicted and actual clay dominance are in good agreement. In addition, the models may be used to devise a weathering sequence of clay minerals from least to most stable (i.e., mica < montmorillonite < vermiculite < kaolinite). Weathering sequences based on existing models place vermiculite before montmorillonite. The models in this study suggest that vermiculite with aluminum as the interlaying cation is common in U.S. soils and is formed in a more intense weathering environment than is montmorillonite; vermiculite should therefore follow montmorillonite in the weathering sequence. This result agrees with many field studies and suggests that the generally accepted sequences need additions and revision. Finally these models support geochemical theories that imply that seasonal wetting and drying are important controls of the formation of secondary clay minerals.

Polygenetic History of Paleosols In Middle-Upper Pennsylvanian Cyclothems of the Illinois Basin, U.S.A.: Part II. Integrating Geomorphology, Climate, and Glacioeustasy

“…This reflects the observation that regional climate and hydrology are important controls on physical and chemical processes that affect soil morphological and mineralogical development (Birkeland 1984;Folkoff and Meentemeyer 1987;Yemane et al 1996;Wilson 1999). As such, the stratigraphic and spatial distribution of soil morphology and clay mineralogy is commonly used in paleosol studies as an indicator of paleoclimate, paleoecology, paleohydrology, and ancient landscape evolution (Retallack 1983;Joeckel 1991Joeckel , 1995Kraus and Bown 1993;Bestland et al 1997;Stern et al 1997; and has provided a better understanding of the allocyclic and autocyclic processes responsible for sediment accumulation and paleosol development in ancient sedimentary systems (Kraus 1987;Wright and Robinson 1988;Smith 1990; Kraus and Aslan 1993;McCarthy et al 1999;McCarthy and Plint 2003).…”

Polygenetic History of Paleosols In Middle-Upper Pennsylvanian Cyclothems of the Illinois Basin, U.S.A.: Part I. Characterization Of Paleosol Types And Interpretation Of Pedogenic Processes

“…Kaolinite occurs in every paleosol type in the IB. Kaolinite is typically formed by weathering of aluminosilicates under acidic, warm, humid conditions in well-drained and highly weathered soils characterized by long periods of leaching (Schwertmann 1985;Folkoff and Meentemeyer 1987;Dixon 1989;Dixon and Skinner 1992;Wilson 1999). The distinct stratigraphic distribution of the relative abundance of kaolinite in IB paleosols (Fig.…”

Evaluating Soil Genesis and Reforestation Success on a Surface Coal Mine in Appalachia

“…Ptimary minerals such as mica and feldspar provide the initial sources of nutrients in mine soils, dissolving to fotm vermiculite, smectite, kaolinite, and gibbsite depending on climatic conditions (Arocenaetal., 1994;Jackson, 1965;Wilson, 1975). Weathering of these soil minerals is dependent on wet-dry cycles and the overburden particle size (Folkoff and Meentemeyer, 1987) because soil minerals have low solubilities and slow rates of dissolution (Katathanasis, 1989) and clay particles have greater weathering rates than sandiet size particles (Kolka et al, 1996). Therefore, reclaimed soils forming out of sand and siltstone materials could be expected to have a lower nutrient content and may require fertilization (Burger et al, 2005a).…”