Abstract
Polymineralic aggregates composed of clinopyroxene, Fe-Ti oxide minerals, apatite and accessory K-feldspar, biotite, and amphibole are enclosed in cumulus plagioclase grains in the Middle Zone of the Skærgaard intrusion. The chemistry of the minerals in the aggregates, and the textural relations between the aggregates and the host plagioclase grains indicate that they represent inclusions of the contemporaneous melt of the Skærgaard intrusion. Through mass balance calculations a quantitative estimate of the melt composition for this level in the intrusion can be obtained, and this estimate confirms that the silica content in the Middle Zone melt was similar to, or possibly even lower than, the silica content in the initial Skærgaard melt, and relatively enriched in iron.
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Hanghøj, K., Rosing, M.T. & Brooks, C.K. Evolution of the skærgaard magma: evidence from crystallized melt inclusions. Contr. Mineral. and Petrol. 120, 265–269 (1995). https://doi.org/10.1007/BF00306507
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DOI: https://doi.org/10.1007/BF00306507