Learning objectives
The main objective of this course is to provide a basic understanding of the magma generation in the different geodynamic environments through time and the relations between magmatic/metamorphic processes and plate tectonics. The acquired skills will also enable the analysis and resolution of issues related to the origin and exploration of critical raw materials for the energy transition.
Prerequisites
Basic (first degree) knowledge of chemistry, mineralogy, petrography, geochemistry.
Course unit content
1-APPLICATION OF TRACE ELEMENT AND ISOTOPE GEOCHEMISTRY TO PETROLOGY
2-PETRO-TECTONIC ASSOCIATIONS:
-Mid-ocean ridge magmatism
-Mantle plumes and oceanic islands
-Arc magmatism (island arcs, active continental margins)
3-CASE STUDIES BASED ON FIELD OCCURRENCES IN THE ALPS AND NORTHERN APENNINE
Within the course, the natural carbonation processes of rocks (with implications for CCSs) will be also considered, as well as the formation of deposits of some critical elements (Lithium, Rare Earths, Copper, Cobalt) in relation to petrogenetic processes in different geodynamic environments.
Full programme
INTRODUCTION
-Mantle composition and heterogeneity
-Causes of melting and origin of magmas
1-GEOCHEMISTRY OF TRACE ELEMENTS AND RADIOGENIC ISOTOPES: PETROLOGICAL APPLICATIONS
-Principles of geochemistry of trace elements: partition coefficients, compatible and incompatible elements, representation of trace elements (normalizations)
-Geochemical models of crystallization, mixing, AFC, partial melting
-Radiogenic isotopes as tracers of petrogenetic processes: Rb / Sr, Sm / Nd, Lu / Hf, Re / Os, U-Pb-Th systems
-Model ages, internal isochrons, closure temperature
2-GEOCHEMICAL CHARACTERISTICS OF MAGMAS AND PETROGENETIC PROCESSES AT DIFFERENT GEODYNAMIC SETTINGS:
DIVERGENT PLATE BOUNDARIES AND MID-OCEAN RIDGES
-structure, composition and lithologies in the modern and fossil oceanic lithosphere
-oceanic lithosphere at fast, slow and ultra-slow spreading-ridges; oceanic core complexes
-mineralogy and geochemistry of MORB and of the lower oceanic crust
-petrogenesis of MORBs, segregation and ascent: from single melt increments to aggregated melts
-geochemical and isotopic heterogeneity in the MORB source
-plume-ridge interactions
-hydrothermal alteration of the oceanic crust
-serpentinization processes and their petrogenetic relevance
MAGMATISM AT CONVERGENT PLATE BOUNDARIES
- distribution, type and structure of magmatic arcs
- magmatic series in intra-oceanic arcs: petrographic, mineralogical and geochemical characters (FAB, boninites, adakites, arc tholeiites, shoshonites)
- sources of magmas and their evolution
- melting/ dehydration of subducted lithosphere
- melting of the mantle wedge
- release of fluids / melts from the slab and transfer of components from the slab to the mantle wedge: experimental studies and HP-UHP
metamorphic rocks as natural laboratories
- role of serpentinites
- new petrogenetic models involving diapiric ascent and melting of melanges from the subducted slab
- isotopic tracers of arc processes (Sr, Nd, Pb, B, Be)
- brief overview of some element cycling (e.g. C and S)
- continental arcs: magmatic series and the role of the continental lithosphere; examples from the Andes and the Cascade Range
- origin of granitic magmas: processes of differentiation, anatexis (fluid-present and fluid-absent melting), hybridization
OCEANIC INTRAPLATE MAGMATISM AND MANTLE PLUMES
-global distribution and tomographic images of hotspots and of subducted plates
-type of OIB magmas
-isotopic variations of Sr, Nd, Hf, Pb, Os and mantle reservoirs (“geochemical geodynamics and the mantle zoo”)
-relationships between mantle plumes and crustal recycling processes
-nature and origin of components in the sources of OIB magmas
-role of pyroxenites
-Sobolev model and Di-CaTsch-Fo-Qtz system
-structure and melting in a mantle plume
CONTINENTAL INTRAPLATE MAGMATISM
-basaltic plateaux
-composition and origin of carbonatitic magmas
-ultrapotassic magmas
3- CASE STUDIES:
-ophiolites of the Internal Ligurian Units (N Apennine) as example of oceanic lithosphere formed at a slow/ultra-slow spreading ridge
-ophiolites of the External Ligurian Units (N Apennine) as example of oceanic lithosphere originated at an ocean-continent transition zone
-continental rifting and oceanization processes
-post-Variscan magmatism and the crustal section of the Ivrea area (Southern Alps)
-notes on the architecture of the Alpine and Apennine chain and the main magmatic and metamorphic events
-Plio-Quaternary magmatic activity in Italy
Bibliography
Slides, scientific articles and links to web sites will be available to download by the students on the web platform “Elly”.
Materials could be updated during the Course.
TEXTBOOKS
- John D. Winter (2010), Principles of igneous and metamorphic petrology, Ed. Prentice Hall
- H. Rollinson (1998) - Using geochemical data (cap. 4 e 6)
- W.M. White: Geochemistry (Wiley)
- A. Philpotts and J. Ague, Principles of Igneous and Metamorphic Petrology (Cambridge University Press)
Teaching methods
Slides provided during classes will be weekly available to download on Elly platform. To download the slides, students need to be registered on-line to the Course. Please note that the slides cannot replace lectures or Textbooks but are considered part of the accompanying instructional materials. Students should frequently control materials and other informations provided n the Elly web site.
- 1. Lectures
- 2. Field excursions: 5 days of fieldwork on selected and well known outcrops from the N Apennine/W Alps/Elba Island which will provide examples of oceanic lithosphere, mantle heterogeneity, continental lower crust and orogenic metamorphism
Assessment methods and criteria
The assessment of learning will take place through a single final test via oral exam including:
-discussion of a scientific article from the recent literature on a topic of the course chosen by the student
-one question concerning trace element and radiogenic isotope geochemistry
-two questions about magmatic associations and related geodyamic settings
-one question about case studies from Alps and Apennines
Other information
Information on the aim and content of the course (see above and below) are associated with the relative "Dublin Indicators" (DI) that characterize their purposes. Dublin Indicators: - Knowledge and understanding; - Applying knowledge and understanding; - Making judgements; - Communication skills; - Learning skills.
2030 agenda goals for sustainable development
4
