2001: The hyper-agpaitic stage in the evolution of the Ilímaussaq alkaline complex
The term hyper-agpaitic covers mineral associations characterised by a wealth of Na-rich min-erals such as natrosilite, zirsinalite, ussingite, vuonnemite, vitusite and lomonosovite. This mineral association clearly indicates a higher degree of alkalinity than for agpaitic rocks in general. In the I...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.588.2914 http://www.geus.dk/publications/bull-gl/nr190/nr190_p083-094.pdf |
| Summary: | The term hyper-agpaitic covers mineral associations characterised by a wealth of Na-rich min-erals such as natrosilite, zirsinalite, ussingite, vuonnemite, vitusite and lomonosovite. This mineral association clearly indicates a higher degree of alkalinity than for agpaitic rocks in general. In the Ilímaussaq complex hyper-agpaitic mineral associations occur not only in peg-matites and hydrothermal veins as in the Kola complexes, Khibina and Lovozero, but also in highly evolved lujavrites and in the fenitised volcanic rocks in the roof of the complex. This paper reviews the occurrences of hyper-agpaitic mineral associations in the Ilímaussaq com-plex. The mineral assemblages are determined by an interplay of temperature, pressure, oxy-gen fugacity, alkalinity, especially the concentration of Na, and contents of elements such as |
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