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UNIVERSITY OF LONDON
BSc and MSci EXAMINATION 2005
For internal students of Imperial College London
Taken by students of Geoscience
This paper is also taken for the relevant examination for the Associateship of the Royal School of Mines
MINERAL DEPOSITS GEOLOGY
Tuesday 26th April 2005, 14:00 to 17:00
Answer ALL questions from Section A and THREE questions from Section B
The structure of this examination paper is as follows:
Section A (2 questions)
Section B (6 questions)
DO NOT OPEN THIS EXAMINATION PAPER UNTIL
INSTRUCTED TO DO SO BY THE INVIGILATOR
SECTION A
1. Ore-forming processes.
(i) Outline the different processes that can lead to ore formation, giving examples of the types of deposits formed by each process. (10 marks)
(ii) Describe, with the aid of a diagram, the relationship between different plate tectonic environments and ore-forming magmatic and hydrothermal processes. (10 marks)
2. The genesis of Irish Zn-Pb deposits.
(i) With the aid of a diagram, describe the fluid flow models proposed by Hitzman (epigenetic) vs Russell (syngenetic) for the genesis of these deposits. (10 marks)
(ii) What evidence, including geochemical data, exists to support ‘Russell-type’ models?
(10 marks)
SECTION B
3. VHMS and SEDEX deposits.
(i) Describe the geology and tectonic setting of VHMS deposits. (10 marks)
(ii) List the main differences between VHMS deposits and SEDEX deposits. (10 marks)
4. Orthomagmatic deposits.
(i) List the main metals of economic interest concentrated by sulphide immiscibility in magmas. (4 marks)
(ii) Discuss the factors that govern the solubility of sulphur in magmas and the processes that are conducive to sulphur saturation. (6 marks)
(iii) Describe the geological characteristics and formation of an ore deposit with which you are familiar that falls into the orthomagmatic category. (10 marks)
5. Iron and aluminium.
(i) Describe the geology and tectonic setting of the main deposit types in which iron and aluminium are the primary economic constituents. (15 marks)
(ii) Name the main ore minerals that contain iron and aluminium, and give the chemical formulae of these minerals. (5 marks)
6. Hydrothermal gold deposits.
(i) Explain how gold is transported in hydrothermal fluids. (5 marks)
(ii) Summarise the geology of epithermal gold deposits, and discuss possible mechanisms for gold precipitation in these deposits. (15 marks)
7. Summarise the geology and tectonic setting of porphyry copper deposits. Include a diagram outlining the nature of hydrothermal alteration within these systems. (20 marks)
8. Classification of mineral deposits.
(i) Describe the thermal divisions of hydrothermal mineral deposits as proposed by Lindgren (1911). (10 marks)
(ii) Discuss other approaches to the classification of mineral deposits. (10 marks)