The Magmatic and Fluid Evolution of the Motzfeldt Intrusion in South Greenland: Insights into the Formation of Agpaitic and Miaskitic Rocks
The 1275 Ga Motzfeldt intrusive complex in the Gardar failed-rift Province in South Greenland formed from six successively intruding melt batches (SM1^SM6) interpreted to be derived from a common magma source at depth. Five units (SM1^SM5) crystallized an alka-line to peralkaline, miaskitic mineral...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
| Published: |
2008
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| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.540.7711 http://petrology.oxfordjournals.org/content/49/9/1549.full.pdf |
| Summary: | The 1275 Ga Motzfeldt intrusive complex in the Gardar failed-rift Province in South Greenland formed from six successively intruding melt batches (SM1^SM6) interpreted to be derived from a common magma source at depth. Five units (SM1^SM5) crystallized an alka-line to peralkaline, miaskitic mineral assemblage of amphibole, clino-pyroxene, feldspar, nepheline, Fe^Ti oxides, zircon, apatite, fluorite and rarely olivine.The last magmatic batch (SM6) is characterized by an agpaitic mineral assemblage of aegirine, nepheline, alkali-feld-spar, eudialyte and rare fluorite or sodalite. Coexisting mafic minerals constrain the crystallization conditions of the miaskitic rocks to about 850^6008C, whereas solidus temperatures below 5008C are indicated by coexisting alkali feldspars in the agpaitic rocks. Oxygen fugacities during the orthomagmatic stage are below the FMQ (fayalite^ magnetite^quartz) buffer (FMQ^05 to ^20)whereas late hema-tite provides evidence of a higher relative oxygen fugacity during |
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