The main Dartmoor granites; petrogenesis and comparisons with the Carnmenellis and Isles of Scilly granites

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Authors:Stone, M.
Author Affiliations:Primary:
University of Exeter, Earth Resources Centre, Exeter, United Kingdom
Volume Title:Proceedings of the Ussher Society
Source:Proceedings of the Ussher Society, Vol.8 (Part 4), p.379-384. Publisher: Ussher Society, Bristol, United Kingdom. ISSN: 0566-3954
Publication Date:1995
Note:In English. 32 refs.; illus., incl. 3 tables
Summary:The sequence from marginal coarse-grained megacrystic biotite granite (CGM) through poorly megacrystic granite to fine-grained granite in the Dartmoor pluton is magmatic and broadly follows the variation patterns observed in the other two studied plutons. Like them, the Dartmoor granites contain high trace-alkalis, Nb, F, Sn, U and Th which, together with high Δ18O, suggest a crustal S-type source though, unlike them, the CGM granite is more basic, has a lower initial 87Sr/86Sr ratio, higher total REE, flatter REE patterns, and metaluminous to peraluminous basic microgranite (BM) enclaves containing sporadic hornblende and titanite. These more I-type characteristics suggest the participation of a minor, but important, subcrustal component. Continuity in several features with BM granites indicates transition from granitic rocks with some I-type to mainly S-type features. Additional evidence for the subcrustal role is provided by the associated nearby Permian volcanism and Li-mica granite and recent isotope data. [R.E.S.]
Subjects:Alkaline earth metals; Biotite granite; Carnmenellis Granite; Chemical composition; Genesis; Granites; Igneous rocks; Intrusions; Isotope ratios; Isotopes; Metals; O-18/O-16; Oxygen; Petrology; Plutonic rocks; Plutons; S-type granites; Sr-87/Sr-86; Stable isotopes; Strontium; Devon England; England; Europe; Great Britain; United Kingdom; Western Europe; Dartmoor Granite; Isles of Scilly Granite
Abstract Numbers:96M/2239
Record ID:1997058594
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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