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PETROLOGY

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Versione italiana
Academic year
2015/2016
Teacher
COSTANZA BONADIMAN
Credits
6
Didactic period
Secondo Semestre
SSD
GEO/07

Training objectives

The Course gives the chance to understand the geochemical modelling applied to magmatic processes, using the geochemical tolls (mainly analytical geochemistry)
The course is aiming at acquiring the fundamental chemical, physical and petrographic tools for the quantitative modelling of the magmatic processes, both regarding magma production trough partial melting and their differentiation trough fractionation processes in magma chamber.
The basic acquired abilities (that are the capacity of applying the acquired knowledge) will be:
• to reproduce the magma geochemical composition
• to determine the chemical-physical condition of magma formatin
• use of elemental and isotopic geochemistry to incesticgate the geodynamic processes.

Prerequisites

Concepts and the knowledge provided by the Courses of “Geochimica”, “Laboratorio di Petrografia” e “Petrografia” course are mandatory. Basic concepts of the analytical methods to acquire major , trace and isotopic measurements from the “Analisi chimiche dei Geomateriali”” Course are also strongly recommended.

Course programme

The course forecasts 48 hours; 36 of teaching in frontal lectures and 12 of practices, discussing “key studies”.
The use of major elements for petrological modelling (12 hours)
• Whole rock analyses using X-Ray fluorescence (XRF), in situ analyses of single minerals using electron microprobe (EMP), analytical errors, reference standards, energy dispersion system analyses (EDS) and wavelength dispersion system analyses (WDS).
• Determination of redox conditions of magmas andEarth mantle calculated from the mineral analyses.
• Geothermometers and geobarometers.
• Mass balance calculation for the modal composition of rocks and eutectic points.
• Melting and fractionation models.
• Numerical examples and exercise with computer

The use of trace elements in the petrological modelling (12 hours)
• Whole rock analyses using ICP-MS (Inductively Coupled Plasma with Mass Spectrometer), in situ analyses using Laser Ablation Microprobe (LAM) ICP-MS and ion microprobe Secondary Ions Mass Spectrometer)
• Partitioning coefficients, compatible and incompatible elements. Trace element distributions during equilibrium partial melting and magmatic differentiation processes.
• Numerical examples and exercise with computer.

Isotope petrology: stable and radiogenic isotopes, (12 hours)
• Behaviour of radiogenic isotoes during partial melting and differentiation processes. Rb-Sr , Sm-Nd, Lu-hf and Re-Os systematics for defining petrogenetic processes.
• Crustal contamination.
Magmatism and geotectonic environments. Mid-Ocean Ridge, Suprasubduction and Within-Plate magmatic systems. Geochemical component distributions in the Upper and Lower Mantle and their inferences for convective models.

Evaluation, calculation and discussion (12 hours) of key studies related to:
• Magma source mantle petrology (partial melting models)
• Magma petrology (fractionation and differentiation)

Didactic methods

The course is organized as follow:
• frontal lessons on all the course’s topics;
• practices using PC spread sheet reproducing mass balance programmes for fractionation and partial melting processes.

Learning assessment procedures

Oral presentation of scientific paper (selected among those listed ) as “original” research. Students have to reproduce calculation, modelling and graphics and discuss results and conclusion to a public audience of master and PhD students.

Reference texts

Scientific papers published on petrological and geochemical magazines (i.e. Journal of Petrology and Lithos).
Rollinsons H., 1993. Using geochemical data: evaluation, presentation, interpretation. Longman Scientific & Techinal
Wilson M. 1988. Igneous petrogenesis. A global tectonic approach. Unwin Hyman.