G9811 Geochemistry of exogenous processes

Faculty of Science
Autumn 2002
Extent and Intensity
2/1. 3 credit(s) (fasci plus compl plus > 4). Type of Completion: zk (examination).
Teacher(s)
doc. Ing. Jiří Faimon, Dr. (lecturer)
Guaranteed by
doc. RNDr. Rostislav Melichar, Dr.
Department of Geological Sciences – Earth Sciences Section – Faculty of Science
Contact Person: Běla Hrbková
Prerequisites (in Czech)
! G9810 Geochem. exogen. proc.
Course Enrolment Limitations
The course is also offered to the students of the fields other than those the course is directly associated with.
fields of study / plans the course is directly associated with
Course objectives
The aim of the course is advanced understanding of the geochemical processes proceeding under conditions of earth surface. There are discussed all physical, chemical, thermodynamic and kinetic aspects of rock weathering. Rock-water interaction is presented from the general view of a diffuse model, reaction model and molecular model (the transition state theory). Part of the course is applied to nucleation and crystal growth. In detail, the geochemistry of clay minerals is discussed. High attention is paid to the models of Al-pH and Al-Si-pH systems and to the diagrams of predominant stability in the systems of Na-Al-Si-H2O, K-Al-Si-H2O, and Ca-Al-Si-H2O. Finally, the transport of weathering products into sedimentary basins, the particle sedimentation, and the evolution of sediments after their deposition is discussed.
Syllabus
  • Rocks stability at surface conditions: Non-stability of igneous and metamorphic rocks. Rock system evolution. Entropy and Gibb's energy. Goldish's scheme.

    Rock weathering: Physical and chemical weathering. Aluminosilicate weathering. Reversibility and irreversibility of processes. The model of diffusion through surface layer. The model of surface reaction. The role of atmosphere and waters. The buffering of waters by CO2. Biogeochemical processes.

    The kinetics of rock-water interaction: Experiments. Box-models. Mass reservoirs, fluxes. Rate equations, rate constants. Steady state, equilibrium. Arhenius' equation. Pre-exponential factor. Activation energy.

    Transition State Theory: Elementary processes. Theory of activated complex. Modeling, computation. Potential barrier. Thermodynamic approach. Rate of interaction. Chemical affinity.

    Saturation state: Thermodynamics of dissolution. Saturation index. Supersaturation, equilibrium and under-saturation of solutions.

    Nucleation theory: Thermodynamics of surfaces. Interfacial surface energy. Polymerization, condensation. Homogenous and heterogeneous nucleation. Clusters, nuclea, and critical nucleus. Potential barrier. Supersaturation influence.

    Crystal growth: Growth mechanisms. Ostwald's step rule, re-crystallization. The formation of secondary mineral phases. Dioctaedral gibbsite layer. Trioctaedral brucite layer. Amorphous SiO2 gels, quartz stability.

    Clay minerals: 1:1 layer minerals: kaolinite, halloysite. Stability and solubility. 2:1 layer minerals: smectite (pyrophyllite, montmorillonite, beidellite), vermiculite. 2:1:1 layer minerals: chlorites.

    Models of secondary phase formation: Al-pH system, equilibrium boundary, solution and mineral stabilities. Al-Si-H2O system, kaolinite, gibbsite, and pyrophyllite stability.

    Diagrams of predominant stability: Geofyzikální faktory (tektonika, teplota, tlak, čas). Geochemické faktory. Syndiageneze (počátční stadium, fáze ranného pohřbení), anadiageneze (lithifikace, srážení tuhé fáze, cementace, rekrystalizace), a epidiageneze (vyzdvižení tělesa, zvýšení propustnosti, zvětrávání). Authigeneze, vznik nových minerálních fází (slídy, zeolity, jílové minerály, sulfidy, sulfáty, gely SiO2, živce, karbonáty)

    systems. Construction. Stability fields. Equilibrium lines. Reaction path and system evolution.

    Dynamic model of rock weathering: Influence of climatic condition. Annual precipitation. Drainage. Soil water composition and concentrations.

    Transport of weathering products: Flow of streams. Potential and kinetic energy of water. Laminar and turbulent flow. Reynolds and Froude number. Critical velocity, critical shear stress. Bed load. Suspended load. Total load. Colloid transport. Transport in porous media.

    Sedimentation: Sedimentary basins. Tectonic influence. Settling of particles: Stokes' and Newton's equations. Effects of motion, particle roughness, and shape. Particle rotation.

    Sediment rheology: Fluid viscosity, effect of particles. Einstein's equations. Behavior of liquid under stress. Newton liquid, shear thinning, shear thickening. Plastic flux, rheopexy, thixotropy. Eddy viscosity.

    Diagenesis: Geophysical factors (tectonics, temperature, pressure, time). Geochemical factors and processes. Syndiagenesis (initial stage, early burial stage). Anadiagenesis (lithification, precipitation, cementation, re-crystallization). Epidiagenesis: (permeability, weathering by meteoric waters). Authigenesis: (phases of diagenesis, micas, zeolites, clay minerals, gypsum-anhydrite, silica gels, feldspars, carbonates).
Literature
  • Chemical weathering rates of silicate minerals. Edited by Art F. White - Susan Louise Brantley. Washington, D.C.: Mineralogical Society of America, 1995, xv, 583. ISBN 0939950383. info
  • DREVER, James I. The Geochemistry of Natural Waters. Prentice Hall, 1997, 450 pp. ISBN 0-13-272790-0. info
  • APPELO, C.A.J. and D. POSTMA. Geochemistry, Groundwater and Polution. 1st ed. Rotterdam/Brookfield: A.A.Balkema, 1994, 519 pp. ISBN 905410 106 7. info
  • STUMM, Werner and James J. MORGAN. Aquatic chemistry : chemical equilibria and rates in natural waters. New York: John Wiley & Sons, 1995, xvi, 1022. ISBN 0-471-51184-6-. info
  • MCLANE, Michael. Sedimentology. New York: Oxford University Press, 1995, xiii, 423. ISBN 0195078683. info
  • Diagenesis, I. Edited by George V. Chilingar - K. H. Wolf. Amsterdam: Elsevier, 1988, 591 s. ISBN 0444427201. info
  • PFEIFFER, Hubert, Thomas KLUPSCH and Werner HAUBENREISSER. Microscopic theory of crystal growth. Berlin: Akademie-Verlag, 1989, 400 s. ISBN 3055006844. info
  • KUKAL, Zdeněk. Základy sedimentologie. 1. vyd. Praha: Academia, 1986, 466 s. info
  • MILLOT, Georges. Geology of clays : weathering, sedimentology, geochemistry. New York: Springer-Verlag, 1970, 429 s. info
Language of instruction
Czech
Further Comments
The course is taught annually.
The course is taught: every week.
Listed among pre-requisites of other courses
The course is also listed under the following terms Autumn 2007 - for the purpose of the accreditation, Autumn 2010 - only for the accreditation, Autumn 2003, Autumn 2004, Autumn 2005, Autumn 2006, Autumn 2007, Autumn 2008, Autumn 2010, Autumn 2011 - acreditation, Autumn 2012, Autumn 2014, Autumn 2016, Autumn 2018, Autumn 2020, Autumn 2022, Autumn 2024.
  • Enrolment Statistics (Autumn 2002, recent)
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