Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway

The Bamble sector of southern Norway comprises metagabbros and metasediments that were metasomatically altered to various extents during a late stage of the Sveconorwegian orogeny (~1.06 Ga). The infiltration of highly saline brines along veins led to penetrative scapolitizationand albitization on a...

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Main Authors: Bast, R., Scherer, E., Mezger, K., Austrheim, H., Ludwig, T., Marschall, H., Putnis, Andrew, Lowen, K.
Format: Journal Article
Published: Springer 2014
Subjects:
Online Access:http://hdl.handle.net/20.500.11937/35594
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author Bast, R.
Scherer, E.
Mezger, K.
Austrheim, H.
Ludwig, T.
Marschall, H.
Putnis, Andrew
Lowen, K.
author_facet Bast, R.
Scherer, E.
Mezger, K.
Austrheim, H.
Ludwig, T.
Marschall, H.
Putnis, Andrew
Lowen, K.
author_sort Bast, R.
building Curtin Institutional Repository
collection Online Access
description The Bamble sector of southern Norway comprises metagabbros and metasediments that were metasomatically altered to various extents during a late stage of the Sveconorwegian orogeny (~1.06 Ga). The infiltration of highly saline brines along veins led to penetrative scapolitizationand albitization on a regional scale and the local deposition of Fe–Ti oxides. Typical secondary mineralassemblages include either scapolite + apatite + amphibole + phlogopite + tourmaline, or albite + epidote + calcite + chlorite + white mica, indicating that the fluids introduced large amounts of Na, Cl, Mg, Ca, K, P, and B to the system. Metasomatic tourmalines associated with different alteration stages as identified by variations in majorelement composition and initial 87Sr/86Sr were analyzedfor B isotopic compositions to constrain possible sources and the evolution of the hydrothermal fluid(s). Measured d11B values range from -5 to +27 ‰ relative to SRM-951, suggesting marine evaporites interlayered with various amounts of continental detritus and pelagic clay as a possible B source reservoir. The influence of a seawater-derived component is clearly indicated by the heavy B isotope signature of tourmaline related to Al–Mg-rich metapelites. In contrast, negative d11B values can be explained by the influence of pneumatolytic fluids associated with granitic pegmatites. On a regional scale (i.e., several km), d11B values in tourmaline vary widely, whereas variations within a single outcrop (tens of m) are typically small and can be ascribed to different generations of tourmaline related to several fluid pulses.
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spelling curtin-20.500.11937-355942017-09-13T15:27:12Z Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway Bast, R. Scherer, E. Mezger, K. Austrheim, H. Ludwig, T. Marschall, H. Putnis, Andrew Lowen, K. Tourmaline Metasomatism Boron isotopes Strontium isotopes Fluid source Bamble sector The Bamble sector of southern Norway comprises metagabbros and metasediments that were metasomatically altered to various extents during a late stage of the Sveconorwegian orogeny (~1.06 Ga). The infiltration of highly saline brines along veins led to penetrative scapolitizationand albitization on a regional scale and the local deposition of Fe–Ti oxides. Typical secondary mineralassemblages include either scapolite + apatite + amphibole + phlogopite + tourmaline, or albite + epidote + calcite + chlorite + white mica, indicating that the fluids introduced large amounts of Na, Cl, Mg, Ca, K, P, and B to the system. Metasomatic tourmalines associated with different alteration stages as identified by variations in majorelement composition and initial 87Sr/86Sr were analyzedfor B isotopic compositions to constrain possible sources and the evolution of the hydrothermal fluid(s). Measured d11B values range from -5 to +27 ‰ relative to SRM-951, suggesting marine evaporites interlayered with various amounts of continental detritus and pelagic clay as a possible B source reservoir. The influence of a seawater-derived component is clearly indicated by the heavy B isotope signature of tourmaline related to Al–Mg-rich metapelites. In contrast, negative d11B values can be explained by the influence of pneumatolytic fluids associated with granitic pegmatites. On a regional scale (i.e., several km), d11B values in tourmaline vary widely, whereas variations within a single outcrop (tens of m) are typically small and can be ascribed to different generations of tourmaline related to several fluid pulses. 2014 Journal Article http://hdl.handle.net/20.500.11937/35594 10.1007/s00410-014-1069-4 Springer restricted
spellingShingle Tourmaline
Metasomatism
Boron isotopes
Strontium isotopes
Fluid source
Bamble sector
Bast, R.
Scherer, E.
Mezger, K.
Austrheim, H.
Ludwig, T.
Marschall, H.
Putnis, Andrew
Lowen, K.
Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway
title Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway
title_full Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway
title_fullStr Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway
title_full_unstemmed Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway
title_short Boron isotopes in tourmaline as a tracer of metasomatic processes in the Bamble sector of Southern Norway
title_sort boron isotopes in tourmaline as a tracer of metasomatic processes in the bamble sector of southern norway
topic Tourmaline
Metasomatism
Boron isotopes
Strontium isotopes
Fluid source
Bamble sector
url http://hdl.handle.net/20.500.11937/35594