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| Titel |
Magmatic origin of alkaline meta-igneous rocks from Chamberlindalen, SW Svalbard |
| VerfasserIn |
Karolina Goluchowska, Abigail Barker, Maciej Manecki, Jerzy Czerny, Jarosław Majka |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250092600
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| Publikation (Nr.) |
 EGU/EGU2014-6956.pdf |
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| Zusammenfassung |
| This study focuses on the late Neoproterozoic meta-igneous rocks of SW Svalbard
to determine their magmatic evolution, conditions of magma storage and origin.
The samples from the Chamberlindalen area form an alkaline igneous suite, from
which thin dikes and intrusive bodies have been collected. The rocks in question
intrude Late Neoproterozoic metasediments and are surrounded by occurrences of
Neoproterozoic metabasalts in contrast to highly alkaline the Chamberlindalen
intrusions.
The rocks from Chamberlindalen are divided into two groups based on their geochemistry,
mineralogy and field relationships. The dikes, classify as minettes, belonging to the
lamprophyre group and contain mainly euhedral, elongated phlogopite and additionally
clinopyroxene and feldspar. The rest of the samples are highly magnesian and are classified as
alkali gabbro. The alkali gabbros contain primary magmatic minerals such as clinopyroxene,
calcic amphibole and mica in different proportions. The alkali gabbros are enriched in LREE
and HFSE and depleted in P, K and HREE. The minette dikes are always more enriched in
HFSE and REE in comparison to the alkali gabbros. The mineral chemistry of the
alkali gabbros reveals that pyroxenes are represented by diopside with Wo46-51
En35-46 Fs6-14, and calcic amphibole by kaersutite. The Mg# number for diopside is
from 72 - 88, whereas for kaersutite Mg# number is 51 - 74. Thermobarometry
calculations for diopside and kaersutite have been performed. In the alkali gabbros from
Chamberlindalen, diopside crystallized between 0.7 - 8 kbar and 1152 - 1233°C.
Results for kaersutite reveal that they crystallized between 5 - 17 kbar and 1043 -
1215°C.
For diopside the main crystallization was between 10 and 38 km, whereas for kaersutite, the
main crystallization was between 30 and 50 km. Clinopyroxene and minor kaersutite also
show a zone of crystallization at 2 to 10 km. This reflects a main crystallization zone at 10 -
50 km throughout the continental crust and a shallower zone of emplacement at 2 - 10
km.
The geochemistry of the alkali meta-igneous suite at Chamberlindalen will be compared with
local greenstones and their trace elements geochemistry will be used to discuss their
origin.
This research is supported by NCN No.2012/05/N/ST10/03594 |
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