Syllabus
1. Physical properties of magma and diversity of the igneous rocks o Composition of magma vs. composition of magmatic rock o Heat sources for partial melting o Physical properties of magmas: temperature, volatiles, density, viscosity o Classification of igneous rocks
§ Qualitative parameters:
· Texture
· Silica saturation
· Alumina saturation
§ Quantitative parameters:
· Silica contents
· Geochemical data
· Modal vs. normative composition
· QAPF (modal) classification
· TAS (chemical) classification
· Alkaline, sub-alkaline (series)
· Subdivision of the subalkaline series to tholeiitic and calc-alkaline suites
· Alternatives for altered/weathered samples
· Multicationic parameters, millications 2. Graphical presentation and recalculation of whole-rock geochemical data from igneous rocks o Software available for Microsoft Windows – state of the art
§ Spreadsheets
§ Dedicated programs (MinPet, IgPet, PetroGraph…) o What is R language? o Main features of the GCDkit system o Graphical presentation of various types of whole-rock geochemical data
§ Classification of elements, major and trace elements
§ Presentation of unidimensional data, including small datasets
§ Two-dimensional data, Harker plots, log–log diagrams etc.
§ Three-dimensional data – ternary plots, various 3D projections
§ Spiderplots including their modifications
§ Working with large datasets
§ Looking for anomalies
§ Classification diagrams
§ Geotectonic diagrams o Installation of GCDkit and basic operation (practical exercises) 3. Processes determining/modifying the composition of magmatic rocks o Overview of processes affecting the composition of magmatic rocks o Partial melting and its causes, segregation of melts, field evidence o Differentiation (thermal (Soret) diffusion, thermogravitational diffusion, liquid immiscibility, equilibrium and fractional crystallization, crystal accumulation …) including field and textural evidence o Open-system processes (assimilation, AFC, hybridization – magma mixing and mingling)
Using whole-rock major-element data in genetic interpretation of igneous rocks (mass-balance principles) o Mass balance during fractional crystallization (direct modelling) o The mass-balance equation for partial melting o Binary and ternary mixing o Generalized mixing of m components: matrix formulation o Liquid lines of descent o Reverse modelling of fractional crystallization and partial melting by the least-squares method o Everything is mixing! o Why are major elements alone not enough? 5. Trace elements: concept of partitioning for “diluted” elements o Classification of trace elements according to their geochemical behaviour o Subdivision of the trace elements into those “diluted” in major rock-forming minerals and Essential Structural Components (ESC) forming own accessory phases o Henry’s Law o Mineral–melt equilibria, distribution coefficients (KD) o Physical factors influencing values of distribution coefficients o Compatibility concept o Crystallization: fractional (Rayleigh equation) and equilibrium (direct models) o Partial melting, fractional and batch, various formulations (direct models) o Distinguishing between fractional crystallization and partial melting o Reverse modelling of fractional crystallization by the least-squares method o Reverse modelling of batch melting 6. Trace elements forming accessory minerals (Essential Structural Constituents, ESC) and saturation models o Saturation concept o Behaviour of ESC during fractional crystallization and partial melting o Saturation equations for the most important accessories (zircon, apatite, monazite,…), their main parameters and use in thermometry o Identifying the petrogenetic role of accessory minerals o Studying internal structure of accessory minerals (BSE, CL…) o Dealing with accessory minerals in models o Saturation calculations in GCDkit 7. Open-system processes: hybridization, assimilation, AFC o Classification of enclaves, MME o Interaction of contrasting magmas: magma mingling and mixing o Filed evidence for magma mixing o Using cathodoluminescence (CL) o Microtextural evidence of magma interaction o Assimilation and crustal contamination o „Deep Crustal Hot Zones“ o (Binary) mixing – major/trace elements, mixing test o Processes determining/modifying the isotopic composition of magmatic rocks (closed- and open-system processes) o Radiogenic isotopes– a quick recap:
§ Calculating initial ratio
§ Using Nd isotopes: including epsilon values and model ages
§ SrNd plugin in GCDkit o Binary mixing – single nad two isotopic ratios (direct and reverse modelling) o Assimilation and Fractional Crystallization (AFC) o Energy-Constrained Assimilation–Fractional Crystallization (EC-AFC) and similar models 8. Magmatic crystallization o Variability of magmatic textures. Why shall we study crystallization and why do we need kinetics? o Thermodynamics of crystallization: equilibrium conditions, crystallization in one- and multicomponent systems, thermodynamic driving force o Kinetics: undercooling, nucleation and crystal growth, basic physico-chemical theories o Magmatic texture as a record of kinetic processes: Avrami theory, granularity, crystal size distributions (CSD) and their genesis o Magmatic textures as a record of mechanic processes in the magma chamber o Lifestyle and crystallization style of magma chambers: solidification fronts, cumulates, geochemical implications 9. Diversity and petrogenesis of (subalkaline) basaltic rocks o Variability and classification of basaltoids o Volcanology of basaltic magmas o Information on composition of the Earth’s mantle o Heterogeneity of the upper mantle o M
Annotation
The course is taught in English when at least one international student is enrolled. This course is focused on petrological and compositional variability of igneous rocks as well as petrogenetic processes playing role in their origin (partial melting of various source rocks, relations between compositions of the melt and co-existing crystals during melting and crystallisation processes, fractionation and contamination of magmas).
Addressed are peculiarities and petrogenetic problems of selected rock types and suites in individual geotectonic settings. Particular emphasis is on practical exercises demonstrating the techniques commonly employed in graphical presentation and interpretation of major- and trace-element whole-rock geochemical data as well as radiogenic isotopic compositions.