Saturday, 15 July 2006

Geochemical Landscapes of Alaska.

Bronwen Wang1, Larry P. Gough1, David B. Smith1, and Nils Gustavsson2. (1) U.S. Geological Survey, 4200 University Drive, Anchorage, AK 99508, (2) Geological Survey of Finland, P.O. Box 96, Espoo, FIN-02151, Finland

Geochemical patterns are presented for 23 elements, ash yield, and pH in soils and other unconsolidated surficial materials from 265 collection locations throughout Alaska. Originally published in 1988 these ultra-low density data (approximately one sample per 6,000 km2) are now interpreted based on landscape geochemical principles (such as the role of regional soils groups, climate, and vegetation) that influence observed areal patterns. A 5-division ecoregion classification system is used to evaluate feldspar chemical weathering processes and to examine relations among climate (mean annual temperature and precipitation) and soil properties (chemistry, pH, and organic matter). Principal components analysis of these climatic and soil properties resulted in 5 factors that explain 77 percent of the total variance in the data. The factors were identified as (1) clay or reactive oxides, (2) physiographic or latitude, (3) soil organic matter, (4) carbonate and soil ion exchange, and (5) soil potassium feldspar. These data should prove useful in assessing geochemical baselines and interpreting geochemical landscapes to identify broad regional patterns.

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