Title page for ETD etd-12192000-091339

Type of Document Master's Thesis
Author Reed, Ryan R.
Author's Email Address rreed@vt.edu
URN etd-12192000-091339
Title Factors Influencing Biotite Weathering
Degree Master of Science
Department Crop and Soil Environmental Sciences
Advisory Committee
Advisor Name Title
Zelazny, Lucian W. Committee Chair
Eick, Matthew J. Committee Member
  • vermiculitization
  • kaolinization
  • hydroxy-interlayered vermiculite
  • biotite
Date of Defense 2000-12-09
Availability unrestricted
Factors Influencing Biotite Weathering


Ryan Reed

Lucian W. Zelazny, Chairman

Crop and Soil Environmental Sciences


Weathering of biotite supplies nutrients such as K+ and weathers into vermiculite/montmorillonite or kaolinite, which have varying influences on soil properties and characteristics. This study was conducted to determine if the weathering mechanisms of biotite are controlled by temperature, or if other factors, such as vegetation or leaching intensity dominantly influence the weathering process. A column study investigation was conducted to assess the influence of different acids, simulated rainfall rates, surface horizons, and temperature on the weathering and cation release of biotite. A field investigation was also conducted on the clay mineral fraction of soils in Grayson County, VA formed above biotite granite. Selected acid leachates did show a greater Al+3, Fe+2, and Si+4 release with organic acids (ascorbic, citric, and fulvic) than that with hydrochloric acid treatment at high leachate rates. Loss of K+ is greater with ascorbic acid than all other acids at high leachate rates. Leachate rate interaction with low temperature was an influencing factor in cation release. Field investigations revealed a greater weathering intensity at high elevations evidenced by; (i) higher clay content, (ii) a dominance of 2:1 minerals, (iii) greater surface area in the upper horizons, (iv) minerals indicative of later stages in the biotite weathering mechanism, and (v) precipitation of halloysite in the C horizon at the high elevation site where temperature is lower and a suspected higher leaching intensity occur.

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