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Contrasting P-T conditions recorded in ultramafic high-pressure rocks from the Variscan Schwarzwald (F.R.G.)

This paper presents mineralogical and tex-tural data as well as thermobarometric calculations on ultramafic high-pressure rocks from the Variscan basement of the Schwarzwald (F.R.G.). The rocks form small isolated bodies within low-pressure / high-temperature gneisses and migmatites. The results of...

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Bibliographic Details
Main Authors: Kalt, Angelika (Author) , Altherr, Rainer (Author) , Hanel, Michael (Author)
Format: Article (Journal)
Language:English
Published: 1995
In: Contributions to mineralogy and petrology
Year: 1995, Volume: 121, Issue: 1, Pages: 45-60
ISSN:1432-0967
DOI:10.1007/s004100050089
Online Access:Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1007/s004100050089
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Author Notes:Angelika Kalt, Rainer Altherr, Michael Hanel
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Summary:This paper presents mineralogical and tex-tural data as well as thermobarometric calculations on ultramafic high-pressure rocks from the Variscan basement of the Schwarzwald (F.R.G.). The rocks form small isolated bodies within low-pressure / high-temperature gneisses and migmatites. The results of this study constrain contrasting P-T evolutions for four garnet-bearing ultramafic high-pressure rocks. Two magnesian garnet-spinal peridotites sampled near the southern margin of the Central Schwarzwald Gneiss Complex (CSGC) were equilibrated at 670-740° C and 1.4-1.8 GPa. These P-T conditions are similar to those recorded by eclogites intercalated in the same basement unit. Two garnet websterites sampled from the northern part of the CSGC have comparatively low Mg/(Mg + Fe) and low Cr and Ni abundances and are interpreted as former cumulates. These rocks most probably experienced an initial high-temperature stage within the spinel peridotite stability field, followed by re-equilibration at 740-850° C/3.2-4.3 GPa and subsequent recrystallization at lower pressures. Further petrologic studies have to reveal whether ultramafic high-pressure rocks of the Schwarzwald can generally be assigned to these two groups which are mainly defined by contrasting peak pressures.
Item Description:Gesehen am 10.01.2023
Physical Description:Online Resource
ISSN:1432-0967
DOI:10.1007/s004100050089

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