Growth zoned manganese garnet in chloritoid, graphite schists near Morlaix, North-west France

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Authors:Power, G. M.
Author Affiliations:Primary:
University of Portsmouth, Department of Portsmouth, Portsmouth, United Kingdom
Volume Title:Annual conference of the Ussher Society
Volume Authors:Williams, B.J., editor
Source:Proceedings of the Ussher Society, Vol.8(Part 2), p.132-137; Annual conference of the Ussher Society, United Kingdom, Jan. 1993, edited by B.J. Williams. Publisher: Ussher Society, Bristol, United Kingdom. ISSN: 0566-3954
Publication Date:1993
Note:In English. 17 refs.; illus., incl. 2 tables, geol. sketch map
Summary:Lower Devonian schists near Morlaix, NW Brittany, contain the assemblage garnet-chloritoid-quartz-muscovite-chlorite-rutile- graphite- pyrite. Garnet and chloritoid grew after the first and before the second foliation. Contoured composition maps of garnet reveal Mn-rich cores and sharp increases in Fe close to the rims. Textural sector-growth is well-developed in the cores. The Mn-rich garnet grew below biotite-zone T, promoted by the high Mn in the rock and by CO2, CH4 and H2S in the fluid phase. The second foliation involved extensive pressure solution of quartz and dissolution of chloritoid, and textural sector-growth ceased with this change in conditions. [R.A.H.]
Subjects:Chloritoid; Devonian; Fluid phase; Garnet group; Manganese; Metals; Metamorphic rocks; Mineral assemblages; Nesosilicates; Orthosilicates; Paleozoic; Petrography; Schists; Silicates; Textures; Brittany; Europe; Finistere France; France; Morlaix France; Western Europe; Northwestern France
Abstract Numbers:94M/3821
Record ID:1995010490
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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