The geochemistry, metasomatism and petrogenesis of the granites of the English Lake District

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doi: 10.1144/gsjgs.142.6.1139
Authors:O'Brien, C.; Plant, J. A.; Simpson, P. R.; Tarney, J.
Author Affiliations:Primary:
Univ. Leicester, Dep. Geol., Leicester, United Kingdom
Br. Geol. Surv., United Kingdom
Volume Title:Journal of the Geological Society of London
Source:Journal of the Geological Society of London, Vol.142 ( Part 6), p.1139-1157. Publisher: Geological Society of London, London, United Kingdom. ISSN: 0016-7649
Publication Date:1985
Note:In English. 65 refs.; illus. incl. 5 tables, geol. sketch map
Summary:New analytical data for major and trace elements (including REE) are presented for >150 samples of granitic rocks of this area. Pervasive high-T metasomatism which affected the Shap, Skiddaw and Eskdale intrusions was accompanied by remobilization of the LIL elements (K, Rb, Sr, U) and Li and B, although high-field-strength elements, including REE, remained unaffected except near greisen and mineral veins. The Threlkeld intrusion appears to have suffered loss of Ba and Sr during a low-T event. There is no consistent relationship, however, between granite composition, hydrothermal activity and mineralization which could be used to support a granite cupola model for the mineralization in the area. Three distinct groups of intrusions can be recognized: the Carrock granophyre is a product of tholeiitic fractionation and the Threlkeld and Ennerdale bodies are more typical calc-alkaline intrusions, whereas the Eskdale, Shap and Skiddaw plutons show a progressive evolution towards more complex geochemical patterns, suggesting decreasing hornblende but increasing plagioclase control of fractionation. None of the Lake District granites is convincingly S-type (i.e. formed by partial melting of a sedimentary protolith), and a model of subcrustal magma genesis beneath an evolving arc or continental margin is thought to be more appropriate. [R.A.H.]
Subjects:Calc-alkalic composition; Caledonian Orogeny; Chemical composition; Genesis; Geochemistry; Granites; Granophyre; Greisenization; Hydrothermal alteration; Igneous rocks; Interpretation; Magmas; Materials; Metals; Metasomatism; Paleozoic; Petrology; Plutonic rocks; Rare earths; Tholeiitic composition; Trace elements; England; Europe; Great Britain; Lake District; United Kingdom; Western Europe; Carrock; Ennerdale; Eskdale; Shap; Skiddaw; Threlkeld
Coordinates:N540000 N550000 W0025000 W0034000
Abstract Numbers:86M/1969
Record ID:1986066995
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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