98315 - GEOCHEMICAL INDICATORS OF GEOLOGICAL PROCESSES

Scheda insegnamento

SDGs

L'insegnamento contribuisce al perseguimento degli Obiettivi di Sviluppo Sostenibile dell'Agenda 2030 dell'ONU.

Istruzione di qualità Acqua pulita e servizi igienico-sanitari La vita sott'acqua

Anno Accademico 2021/2022

Conoscenze e abilità da conseguire

This course will provide an integrated and quantitative understanding of the geochemical processes affecting particular groups of elements which can help us understand a range of geological processes. Particular groups of elements act as tracers or indicators for certain geological events, from, for example, the partitioning of trace elements during the differentiation of planetary bodies, to compositional change in magmas during melting and crystallisation, or the changes in solubility of metals in ocean waters associated with redox changes. Certain geological events are better explained by using selected indicator elements to define the physical processes, and this course will follow that outline.

Contenuti

The course will be delivered in two modules.

Module 1 will cover two broad areas of the Earth System (i) processes and the chemical consequences of those in the primary environment (i.e. planetary scale processes of formation and differentiation) (ii) low temperature environments, particularly ocean- and hydro-chemistry. In addition, in Module 1, we will consider some applications of statistical and numerical methods for comparative geochemistry in volcanological and archaeological studies.

Module 2 will cover a range of geochemical processes related to the flow of high-temperature fluids in the lithosphere. These include the transport of metals within hydrothermal aqueous fluids (ore fluids), the precipitation of ore minerals, and the interaction between ore fluids and host rocks (hydrothermal alteration).

The objective of this course is to give students an introduction to a range of geochemical processes, and techniques which allow a range of geological processes to be modelled and understood using geochemical data. These processes allow us to evaluate the processes operating within the solid Earth and hydrosphere, where element concentrations respond to changes in, for example, mineral phase assemblages, or stability/precipitation conditions or sorption characteristics associated with environmental redox or pH variations. Differences in the extent to which various processes operate cause variations in compositions, and awareness of how to assess the extent of these differences may be relevant in attempts to correlate materials between locations or understand the effectiveness of process (from volcanic hazard studies, archaeological provenancing to mine water remediation). We will also therefore look at some appropriate statistical methods to assess differences or similarities in sets of geochemical data.

The causes of any compositional change through a geological process relate to the geochemical behaviour of individual elements, and to explain and understand this, the behaviour of different element groups will be considered in arrange of environments e.g. the REE or transition metals in solid and aqueous environments, or, the where they can be used as proxies for other environmentally sensitive elements (e.g. the REE as proxies for the actinides). Applications related to understanding the behaviour of these geochemical indicators help in environmental studies (e.g. remediation associated with waste disposal or extractive industries) allowing us to plan and manage environmental risk associated with remediation and rehabilitation of natural and man-made pollution.

The high-temperature aqueous fluids will be studied starting from the fundamental properties of water as a solvent, the differences between H2O properties at high- and low-temperature, and their effects on metal transport. These will contrast with the low-temperature fluids in the hydrosphere. Metal transport will be investigated from the perspective of Lewis (Pearson) acid-base classification, which leads to the identification of systematic criteria for metal transport in hydrothermal fluids. The fluid-rock interaction processes will be studied using the mass-transfer calculation approach.

At the end of the course, students will be able to quantify and model geochemical processes in both the primary and secondary environments, and from this to understand how geochemical data can be used to understand or model geological processes, and how the behaviour of different element groups is affected by environment or process, and have the tools how to quantitatively assess these.

Testi/Bibliografia

White W.M. 2020 Geochemistry 2nd edition 960 pp Wiley

Albarede F. 2013. Geochemistry - An Introduction 2nd edition

Chester R. 2002 Marine Geochemistry 2nd edition /Chester and Jickells 2012 Marine Geochemistry 3rd Edition

Treatise on Geochemistry series – The Mantle and Core

The Crust

Oceans and Marine Geochemistry

Environmental Geochemistry.

Langmuir D. 2005 Aqueous Environmental Geochemistry. Prentice-Hall

Additional reading material, from other books, journals or on-line resources, will be indicated to students as required during the course.

Metodi didattici

A range of teaching methods will be employed.

Class teaching will be delivered by lectures, with associated laboratory exercises. Laboratory exercises will include numerical examples, some software modelling and laboratory calculation exercises based on data interpretation.

Student presentations – a 15-minute presentation (as part of Module 1 and Module 2) on the geochemical behaviour of a particular element (prepared by the student) and the geological processes which it indicates. Elements will be chosen for students by a “lottery”. This will give students an opportunity to practice presentation skills and equip themselves for making a presentation in English to a group. Advice on how to prepare an academic presentation will be provided, and the presentation will form the basis for the Oral Exam for Module 1.

Modalità di verifica e valutazione dell'apprendimento

Different assessment methods will be used to evaluate the students: content-based, competence-based and impact-based assessments. Content-based assessment refers to assessment tasks that mainly ask the learner about facts. Competence-based assessments refers to assessment of intended learning outcomes that ask the learner to show ability to also use these facts.

Class participation (for both Module 1 and 2): 10%

Laboratory and other assessed exercises (Module 1): 40% A selection of the laboratory exercises and other assignments will be submitted at particular points throughout the course and be assessed. Submissions must be made on time (timetable will be arranged at the start of the course), unless there are significant mitigating circumstances (e.g. documented medical issues etc) to allow extensions.

Written exam (Module 2): 20%

Presentation and Oral exam (for Module 1 and Module 2): 30%

Strumenti a supporto della didattica

Lectures and seminars

Laboratory exercises

Orario di ricevimento

Consulta il sito web di Nicholas John Geoffrey Pearce

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