Parental magma of the Skaergaard intrusion: constraints from melt inclusions in primitive troctolite blocks and FG-1 dykes

Jakob K. Jakobsen; Christian Tegner; C. Kent Brooks; Adam J.R. Kent; Charles E. Lesher; Troels F.D. Nielsen; Michael Wiedenbeck

doi:10.1007/s00410-009-0416-3

Parental magma of the Skaergaard intrusion: constraints from melt inclusions in primitive troctolite blocks and FG-1 dykes

Jakob K. Jakobsen
, Christian Tegner
, C. Kent Brooks
, Adam J.R. Kent
, Charles E. Lesher
, Troels F.D. Nielsen
, Michael Wiedenbeck

Department of Mapping and Mineral Resources

Research output: Contribution to journal › Article › Research › peer-review

39 Citations (Scopus)

Abstract

Troctolite blocks with compositions akin to the Hidden Zone are exposed in a tholeiitic dyke cutting across the Skaergaard intrusion, East Greenland. Plagioclase in these blocks contains finely crystallised melt inclusions that we have homogenised to constrain the parental magma to 47.4-49.0 wt.% SiO₂, 13.4-14.9 wt.% Al₂O₃ and 10.7-14.1 wt.% FeO^T. These compositions are lower in FeO^T and higher in SiO₂ than previous estimates and have distinct La/Sm_N and Dy/Yb_N ratios that link them to the lowermost volcanic succession (Milne Land Formation) of the regional East Greenland flood basalt province. New major- and trace element compositions for the FG-1 dyke swarm, previously taken to represent Skaergaard magmas, overlap with the entire range of the regional flood basalt succession and do not form a coherent suite of Skaergaard like melts. These dykes are therefore re-interpreted as feeder dykes throughout the main phase of flood basalt volcanism.

Original language	English
Pages (from-to)	61-79
Number of pages	19
Journal	Contributions to Mineralogy and Petrology
Volume	159
Issue number	1
DOIs	https://doi.org/10.1007/s00410-009-0416-3
Publication status	Published - Jan 2010

Keywords

Bulk composition
East Greenland
Melt inclusions
Parental magma
Skaergaard intrusion

Programme Area

Programme Area 4: Mineral Resources

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10.1007/s00410-009-0416-3Licence: CC BY

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@article{99317d27c5024ab5a43d80032505de76,

title = "Parental magma of the Skaergaard intrusion: constraints from melt inclusions in primitive troctolite blocks and FG-1 dykes",

abstract = "Troctolite blocks with compositions akin to the Hidden Zone are exposed in a tholeiitic dyke cutting across the Skaergaard intrusion, East Greenland. Plagioclase in these blocks contains finely crystallised melt inclusions that we have homogenised to constrain the parental magma to 47.4-49.0 wt.\% SiO2, 13.4-14.9 wt.\% Al2O3 and 10.7-14.1 wt.\% FeOT. These compositions are lower in FeOT and higher in SiO2 than previous estimates and have distinct La/SmN and Dy/YbN ratios that link them to the lowermost volcanic succession (Milne Land Formation) of the regional East Greenland flood basalt province. New major- and trace element compositions for the FG-1 dyke swarm, previously taken to represent Skaergaard magmas, overlap with the entire range of the regional flood basalt succession and do not form a coherent suite of Skaergaard like melts. These dykes are therefore re-interpreted as feeder dykes throughout the main phase of flood basalt volcanism. ",

keywords = "Bulk composition, East Greenland, Melt inclusions, Parental magma, Skaergaard intrusion",

author = "Jakobsen, \{Jakob K.\} and Christian Tegner and Brooks, \{C. Kent\} and Kent, \{Adam J.R.\} and Lesher, \{Charles E.\} and Nielsen, \{Troels F.D.\} and Michael Wiedenbeck",

note = "Funding Information: Acknowledgments This work was part of J. K. Jakobsen{\textquoteright}s PhD project, financed by the Science Faculty at the University of Aarhus. Additional financial support was provided by grants from the Danish Natural Science Research Council (CT) and a Fulbright scholarship (JKJ). H. D. Zimmermann is thanked for help with the vertical furnaces for homogenisation of melt inclusions. We are grateful to S. Grundvig in Aarhus for help with the microprobe and to D. Rhede at GFZ Potsdam for technical support with the ionprobe analyses. A. Ariskin is thanked for providing us with the latest version of the COMAGMAT software. S. Gardio, L. Heister and M. A. Gras are thanked for their help with sample preparation and ICPMS analyses. This study has benefited from discussions and comments by I. V. Veksler, J. R. Wilson and K. Hangh{\o}j as wells as reviews by M. C. S. Humphreys and an anonymous reviewer who greatly improved an earlier version of the manuscript. We will also like to thank Jochen Hoefs for his patience and editorial handling.",

year = "2010",

month = jan,

doi = "10.1007/s00410-009-0416-3",

language = "English",

volume = "159",

pages = "61--79",

journal = "Contributions to Mineralogy and Petrology",

issn = "0010-7999",

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AU - Jakobsen, Jakob K.

AU - Tegner, Christian

AU - Brooks, C. Kent

AU - Kent, Adam J.R.

AU - Lesher, Charles E.

AU - Nielsen, Troels F.D.

AU - Wiedenbeck, Michael

N1 - Funding Information: Acknowledgments This work was part of J. K. Jakobsen’s PhD project, financed by the Science Faculty at the University of Aarhus. Additional financial support was provided by grants from the Danish Natural Science Research Council (CT) and a Fulbright scholarship (JKJ). H. D. Zimmermann is thanked for help with the vertical furnaces for homogenisation of melt inclusions. We are grateful to S. Grundvig in Aarhus for help with the microprobe and to D. Rhede at GFZ Potsdam for technical support with the ionprobe analyses. A. Ariskin is thanked for providing us with the latest version of the COMAGMAT software. S. Gardio, L. Heister and M. A. Gras are thanked for their help with sample preparation and ICPMS analyses. This study has benefited from discussions and comments by I. V. Veksler, J. R. Wilson and K. Hanghøj as wells as reviews by M. C. S. Humphreys and an anonymous reviewer who greatly improved an earlier version of the manuscript. We will also like to thank Jochen Hoefs for his patience and editorial handling.

PY - 2010/1

Y1 - 2010/1

N2 - Troctolite blocks with compositions akin to the Hidden Zone are exposed in a tholeiitic dyke cutting across the Skaergaard intrusion, East Greenland. Plagioclase in these blocks contains finely crystallised melt inclusions that we have homogenised to constrain the parental magma to 47.4-49.0 wt.% SiO2, 13.4-14.9 wt.% Al2O3 and 10.7-14.1 wt.% FeOT. These compositions are lower in FeOT and higher in SiO2 than previous estimates and have distinct La/SmN and Dy/YbN ratios that link them to the lowermost volcanic succession (Milne Land Formation) of the regional East Greenland flood basalt province. New major- and trace element compositions for the FG-1 dyke swarm, previously taken to represent Skaergaard magmas, overlap with the entire range of the regional flood basalt succession and do not form a coherent suite of Skaergaard like melts. These dykes are therefore re-interpreted as feeder dykes throughout the main phase of flood basalt volcanism.

AB - Troctolite blocks with compositions akin to the Hidden Zone are exposed in a tholeiitic dyke cutting across the Skaergaard intrusion, East Greenland. Plagioclase in these blocks contains finely crystallised melt inclusions that we have homogenised to constrain the parental magma to 47.4-49.0 wt.% SiO2, 13.4-14.9 wt.% Al2O3 and 10.7-14.1 wt.% FeOT. These compositions are lower in FeOT and higher in SiO2 than previous estimates and have distinct La/SmN and Dy/YbN ratios that link them to the lowermost volcanic succession (Milne Land Formation) of the regional East Greenland flood basalt province. New major- and trace element compositions for the FG-1 dyke swarm, previously taken to represent Skaergaard magmas, overlap with the entire range of the regional flood basalt succession and do not form a coherent suite of Skaergaard like melts. These dykes are therefore re-interpreted as feeder dykes throughout the main phase of flood basalt volcanism.

KW - Bulk composition

KW - East Greenland

KW - Melt inclusions

KW - Parental magma

KW - Skaergaard intrusion

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DO - 10.1007/s00410-009-0416-3

M3 - Article

SN - 0010-7999

VL - 159

SP - 61

EP - 79

JO - Contributions to Mineralogy and Petrology

JF - Contributions to Mineralogy and Petrology

IS - 1

ER -

Parental magma of the Skaergaard intrusion: constraints from melt inclusions in primitive troctolite blocks and FG-1 dykes

Abstract

Keywords

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