ESC3111

Magmatic processes and products

Dr Ian Nicholls and Professor Ray Cas

6 points - Eleven weeks lecture/practical coursework usually first semester - 2-day field excursion (Western District volcanic field) - Prerequisites: ESC2022 - Prohibitions: ESC3011, ESC3022, ESC3051, ESC3062 (refer to department for advice)

Objectives This subject aims to provide basic information on the behaviour of magmas in igneous processes, with a degree of emphasis on the processes and products of basaltic volcanic activity; to treat the global tectonic settings in which magmatism occurs; introduce the chemical principles behind the behaviour of elemental and isotopic systems during generation and evolution of magmas; provide an introduction to the detailed study and interpretation of the mineralogy, textural features, geochemistry and modes of origin of igneous rocks.

Synopsis Igneous petrology examines the origin of magmas by melting of the earth's mantle and crust; magma transport, emplacement and crystallisation; geochemical mass balance in magmatic systems; magma sources and controls on magma genesis in global tectonic settings. Igneous geochemistry includes the principles of the partitioning behaviour of element groups, especially at trace levels, in terms of the chemistry and structures of crystals and melts; trace element and isotopic ratio systematics of magmas and their sources; quantitative trace element modelling of magmatic processes. A volcanology component will examine the magmatic processes involved in various styles of volcanic activity and the nature of the products of contrasted eruptive mechanisms. Practical exercises will emphasise the mineralogy, textures and geochemistry of volcanic and intrusive rocks from a variety of tectonic settings, and also examine the basics of trace element modelling. The field excursion and volcanology practical exercises will examine the field occurrence and physical and mineralogical characteristics of basaltic lavas and pyroclastic deposits.

Assessment Practical work: 30% - Short tests: 5% - Field excursion: 20% - Final examination: 45%

Recommended texts

Cas R A and Wright J V Volcanic successions, modern and ancient Unwin Hyman, 1987
Wilson M Igneous petrogenesis: A global tectonic approach Unwin Hyman, 1989

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