Clinopyroxenes ofthe gabbro cumulates of the Kap Edvard Holm complex, east Greenland
series of conspicuously banded gabbroic rocks. The primary minerals of both lower and upper layered series how a progressive change in composition, from higher to lower temperature phases, with increasing height in the complex. Minor fluctuations in the differentiation of the two series occur but th...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.606.2686 http://www.minersoc.org/pages/Archive-MM/Volume_34/34-268-177.pdf |
| Summary: | series of conspicuously banded gabbroic rocks. The primary minerals of both lower and upper layered series how a progressive change in composition, from higher to lower temperature phases, with increasing height in the complex. Minor fluctuations in the differentiation of the two series occur but the division of the layered rocks into the lower and upper series is based on abrupt and major changes in the compositions of the pyroxenes, olivine and plagioclase. This break is cor-related with the injection of a large volume of undifferentiated magma which oc-curred after much of the lower layered series had consolidated, and from which the rocks of the upper layered series were formed. Twelve pyroxenes, five from the lower and seven from the upper layeT'e d series have been analysed; the relationships between their optical properties and chemical composition, and between the cell parameters and composition are considered. The crystallization trend of the pyroxenes i compared with that of the Skaergaard calcium-rich pyroxenes; it is suggested that the restricted enrichment in iron shown by the Kap Edvard Holm pyroxenes may be related to the higher water-vapour p essures which prevailed |
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