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Soil Genesis and Mineral Transformation Across an Environmental Gradient on Andesitic Lahar

Soil, Water, and Environmental Science Dep., Univ. of Arizona, Shantz Bldg. no. 38, 1177 E. Fourth St., P.O. Box 210038, Tucson, AZ 85721

Nobuhiko Matsuyama

Faculty of Agric. and Life Science, Hirosaki Univ., 3 Bunkyo, Hirosaki, Aomori 036-8561, Japan

Randy A. Dahlgren, Randal J. Southard and Neil Brauer

Land, Air, and Water Resources, Univ. of California-Davis, One Shields Ave., Davis, CA 95616

View larger version (12K): [in this window] [in a new window]   Fig. 1. Total pedon organic C, clay, and free Fe-oxide content (Fed) for soils derived from andesite across an elevation and climate gradient in the Sierra Nevada of California.

View larger version (13K): [in this window] [in a new window]   Fig. 2. Volcanic glass in the very fine sand (VFS) fraction of surface and subsurface horizons of soils derived from andesite across an elevation and climate gradient in the Sierra Nevada of California. Values for each elevation (biome) represent the following horizons: 2700 m (AL-7) A1 and AC; 2450 m (SA-6) A1 and AC2; 2150 m (RF-5) A1 and Bw2; 1700 m (WF-4) A1 and Bw1; 1150 m (PP-3) A and Bt1; 520 m (PO-2) A and Bt1; and 160 m (BO-1) A1 and Bw2.

View larger version (30K): [in this window] [in a new window]   Fig. 3. X-ray diffractograms for random powder mounts of Mg2+-saturated 25°C very fine sand fractions from subsurface horizons of each biome along an elevation and climate gradient on andesite parent materials in the Sierra Nevada, California. The horizons shown from each respective biome are: AL-7, A2; SA-6, A2; RF-5, Bw1; WF-4, Bw1; PP-3, Bt1; PO-2, Bt1; and BO-1, Bw1. The break between PP-3 and WF-4 represents the transition from rain-dominated systems to snow-dominated systems. Drop lines are in nanometers; unlabeled peaks dominantly derive from feldspars.

View larger version (27K): [in this window] [in a new window]   Fig. 4. X-ray diffractograms for oriented Mg2+-saturated 25°C silt fractions from subsurface horizons of each biome along an elevation and climate gradient on andesite parent materials in the Sierra Nevada, California. The horizons shown from each respective biome are: AL-7, A2; SA-6, A2; RF-5, Bw1; WF-4, Bw1; PP-3, Bt1; PO-2, Bt1; and BO-1, Bw1. The break between PP-3 and WF-4 represents the transition from rain-dominated systems to snow-dominated systems. Drop lines are in nanometers; unlabeled peaks dominantly derive from feldspars.

View larger version (19K): [in this window] [in a new window]   Fig. 5. X-ray diffractograms for the clay fraction of the Alpine (AL-7) biome surface horizon. Drop lines are in nanometers.

View larger version (26K): [in this window] [in a new window]   Fig. 6. X-ray diffractograms for K+-saturated 25°C clay fractions from subsurface horizons of each biome along an elevation and climate gradient on andesite parent materials in the Sierra Nevada, California. The horizons shown from each respective biome are: AL-7, A2; SA-6, A2; RF-5, Bw1; WF-4, Bw1; PP-3, Bt1; PO-2, Bt1; and BO-1, Bw1. The break between PP-3 and WF-4 represents the transition from rain-dominated systems to snow-dominated systems. Drop lines are in nanometers.

View larger version (22K): [in this window] [in a new window]   Fig. 7. X-ray diffractograms of Mg2+-saturated and formamide-solvated clays from all horizons of the PP-3 biome. Drop lines are in nanometers. The 1.0-nm peak represents expansion of the halloysite 0.72-nm peak.