Trace element systematics of tourmaline in pegmatitic and hydrothermal systems from the Variscan Schwarzwald (Germany): The importance of major element composition, sector zoning, and fluid or melt composition

An extensive data set on the compositional variation of tourmaline from granitic pegmatites, from migmatitic gneisses and from various types of hydrothermal veins from the Schwarzwald, Germany, is provided. The investigated tourmalines are members of the alkali and X-vacant groups representing mostl...

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Bibliographic Details
Published in:Chemical geology 2013-04, Vol.344, p.73-90
Main Authors: Marks, Michael A.W., Marschall, Horst R., Schühle, Philipp, Guth, Anna, Wenzel, Thomas, Jacob, Dorrit E., Barth, Matthias, Markl, Gregor
Format: Article
Language:English
Subjects:
calcium
cobalt
crystals
data collection
elemental composition
fractionation
isotopes
lead
magnesium
melting
oxygen
Oxygen isotopes
Schwarzwald
Sector zoning
sodium
strontium
temperature
tin
Tourmaline
Trace elements
zinc
zoning
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Summary:An extensive data set on the compositional variation of tourmaline from granitic pegmatites, from migmatitic gneisses and from various types of hydrothermal veins from the Schwarzwald, Germany, is provided. The investigated tourmalines are members of the alkali and X-vacant groups representing mostly dravite–schorl solid solutions with some analyses belonging to the foitite–Mg–foitite series. Oxygen isotope data on quartz–tourmaline pairs indicate formation temperatures between 550 and 350°C for most of the quartz–tourmaline veins. Most of the tourmalines show strong sector zonation, fractionating certain major (e.g., Na, Mg), minor (e.g., Ti, Ca) and trace elements (e.g., Sr, Pb, REE) among the different crystallographic sectors of the crystals. We conclude that comparison of tourmaline compositions for petrogenetic interpretations must be based on the concentrations in the neutral a sector in order to eliminate the effects of intra-crystalline fractionation. Most trace element contents vary over several orders of magnitude with median concentrations generally between 0.1 and 10μg/g. The highest concentrations are found for Zn, V, Sr, Sc, Sn and Li (median concentrations of several tens to hundreds of μg/g) whereas very low median concentrations (
ISSN:0009-2541
1872-6836
DOI:10.1016/j.chemgeo.2013.02.025