The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland
Iron isotopes show small fractionations in igneous rocks emplaced at high temperature , but the processes by which these fractionations originate are still debated. The Skaergaard layered mafic intrusion of East Greenland is a good system to study how iron stable isotopes may fractionate in igneous...
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ftunivnorthcag:oai:libres.uncg.edu/30636 2024-10-29T17:43:19+00:00 The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland NC DOCKS at East Carolina University Pertunen, Brett Anthony 2018 http://libres.uncg.edu/ir/ecu/f/0000-embargo-holder.txt English eng 2018 ftunivnorthcag 2024-10-08T15:22:16Z Iron isotopes show small fractionations in igneous rocks emplaced at high temperature , but the processes by which these fractionations originate are still debated. The Skaergaard layered mafic intrusion of East Greenland is a good system to study how iron stable isotopes may fractionate in igneous systems because it formed from a single pulse of tholeiitic magma. High-precision (0.023 [per mille] , 2-SE) iron isotope ratios were obtained for pyroxene from fresh and altered gabbros and ferrodiorites representative of the Skaergaard intrusion. The [delta]56Fe values of pyroxene vary from -0.102 [per mille] 0.025 [per mille] to +0.114 [per mille] 0.018 [per mille] (2-SE , relative to igneous rocks) , with an overall range of 0.216 [per mille] (n = 13). Poikilitic pyroxene from gabbros of the Lower Zone a and the Upper Border Series g have the lowest [delta]56Fe values , whereas mosaic pyroxene in an altered ferrodiorite of the Upper Border Series [gamma] has the highest [delta]56Fe value. The possible effect of hydrothermal alteration on the iron isotope compositions was investigated for this pyroxene , but it was determined that the pyroxene contains abundant inclusions of magnetite , which increase its [delta]56Fe value , and that hydrothermal alteration did not fractionate iron isotopes in pyroxenes from Skaergaard. The iron isotope composition of pyroxene was investigated in relation to the fractional crystallization of coexisting Fe-Ti oxides magnetite and ilmenite. In the Lower Zone , the [delta]56Fe values of pyroxene systematically increase with magma evolution from the Lower Zone a (-0.102 [plus or equal to] 0.025 [per mille]) to the Lower Zone c (-0.005 [plus or equal to] 0.012 [per mille]). Ferric iron is increasingly incorporated into pyroxene with magmatic evolution in the Lower Zone , allowing for incorporation of more heavy isotopes that result in the increase in [delta]56Fe values. When magnetite saturation occurs at the top of the Lower Zone c , Fe3+ becomes preferentially partitioned into ... Other/Unknown Material East Greenland Greenland University of North Carolina: NC DOCKS (Digital Online Collection of Knowledge and Scholarship) Greenland |
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University of North Carolina: NC DOCKS (Digital Online Collection of Knowledge and Scholarship) |
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ftunivnorthcag |
language |
English |
description |
Iron isotopes show small fractionations in igneous rocks emplaced at high temperature , but the processes by which these fractionations originate are still debated. The Skaergaard layered mafic intrusion of East Greenland is a good system to study how iron stable isotopes may fractionate in igneous systems because it formed from a single pulse of tholeiitic magma. High-precision (0.023 [per mille] , 2-SE) iron isotope ratios were obtained for pyroxene from fresh and altered gabbros and ferrodiorites representative of the Skaergaard intrusion. The [delta]56Fe values of pyroxene vary from -0.102 [per mille] 0.025 [per mille] to +0.114 [per mille] 0.018 [per mille] (2-SE , relative to igneous rocks) , with an overall range of 0.216 [per mille] (n = 13). Poikilitic pyroxene from gabbros of the Lower Zone a and the Upper Border Series g have the lowest [delta]56Fe values , whereas mosaic pyroxene in an altered ferrodiorite of the Upper Border Series [gamma] has the highest [delta]56Fe value. The possible effect of hydrothermal alteration on the iron isotope compositions was investigated for this pyroxene , but it was determined that the pyroxene contains abundant inclusions of magnetite , which increase its [delta]56Fe value , and that hydrothermal alteration did not fractionate iron isotopes in pyroxenes from Skaergaard. The iron isotope composition of pyroxene was investigated in relation to the fractional crystallization of coexisting Fe-Ti oxides magnetite and ilmenite. In the Lower Zone , the [delta]56Fe values of pyroxene systematically increase with magma evolution from the Lower Zone a (-0.102 [plus or equal to] 0.025 [per mille]) to the Lower Zone c (-0.005 [plus or equal to] 0.012 [per mille]). Ferric iron is increasingly incorporated into pyroxene with magmatic evolution in the Lower Zone , allowing for incorporation of more heavy isotopes that result in the increase in [delta]56Fe values. When magnetite saturation occurs at the top of the Lower Zone c , Fe3+ becomes preferentially partitioned into ... |
author |
NC DOCKS at East Carolina University Pertunen, Brett Anthony |
spellingShingle |
NC DOCKS at East Carolina University Pertunen, Brett Anthony The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland |
author_facet |
NC DOCKS at East Carolina University Pertunen, Brett Anthony |
author_sort |
NC DOCKS at East Carolina University |
title |
The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland |
title_short |
The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland |
title_full |
The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland |
title_fullStr |
The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland |
title_full_unstemmed |
The iron isotope composition of pyroxene from the Skaergaard layered mafic intrusion , East Greenland |
title_sort |
iron isotope composition of pyroxene from the skaergaard layered mafic intrusion , east greenland |
publishDate |
2018 |
url |
http://libres.uncg.edu/ir/ecu/f/0000-embargo-holder.txt |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
East Greenland Greenland |
genre_facet |
East Greenland Greenland |
_version_ |
1814272597664202752 |