EXPERIMENTÁLNÍ ZVĚTRÁVÁNÍ PERTHITICKÉHO ŽIVCE

Roč.11,(2004)

Karel Vybíhal Jiří Faimon

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Abstrakt
Perthitic feldspar weathered in batch reactor (weight ratio feldspar/water ~ 4/15) during long-term (300 day) laboratory experiments at ambient conditions. During first 50 days of the experiment, aqueous concentrations of Si, Al, K, Na, and Ca reached limiting values 3.4x10-4, 9.2x10-5, 1.5x10-4, 1.2x10-4, 1.1x10-4 mol/l, respectively. Despite the fact, the studied system was still far away from equilibrium. High supersaturation with respect to secondary minerals (gibbsite, pyrophyllite, Ca-beidellite, K-beidellite, Na-beidellite, and kaolinite) and to primary minerals (albite and K-feldspar) was reached in the solution. Reaction paths on predominant stability diagrams crossed the stability field of gibbsite and kaolinite, and points to the Na-beidelite and K-feldspar stability fields. Based on X-ray diffraction, only muscovite and illite were proved. Electron microprobe analyses showed decreasing Al/Si stoichiometry of secondary phases during time.

Klíčová slova:
experiment; modeling; perthitic feldspar; saturation; secondary phase; weathering
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