A textural record of solidification and cooling in the Skaergaard Intrusion
The clinopyroxene^plagioclase^plagioclase dihedral angle, cpp, in gabbroic cumulates records the time-integrated thermal history in the sub-solidus and provides a measure of textural maturity. Variations in cpp through the Layered Series of the Skaergaard intrusion, East Greenland, demonstrate that...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Text |
| Language: | English |
| Published: |
2007
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.570.3733 http://www.geo.umass.edu/petrology/holness et al_2007_skaergaard.pdf |
| Summary: | The clinopyroxene^plagioclase^plagioclase dihedral angle, cpp, in gabbroic cumulates records the time-integrated thermal history in the sub-solidus and provides a measure of textural maturity. Variations in cpp through the Layered Series of the Skaergaard intrusion, East Greenland, demonstrate that the onset of crystalliza-tion of clinopyroxene (within LZa), Fe^Ti oxides (at the base of LZc) and apatite (at the base of UZb) as liquidus phases in the bulk magma is recorded by a stepwise increase in textural maturity, related to an increase in the contribution of latent heat to the total heat loss to the surroundings and a reduction in the specific cooling rate at the crystallization front of the intrusion. The onset of both liquidus Fe^Ti oxide and apatite crystallization is marked by a transient increase in textural maturity, probably linked to overstepping before nucleation. Textural maturation at pyroxene^plagioclase^plagioclase triple junctions effectively ceases |
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