SIlicate Melt Inclusions from a Mildly Peralkaline Granite in the Oslo Paleorift, Norway

T. H. Hansteen and W. J. Lustenhouwer
Mineralogical-Geological Museum, Sars Gate 1, N-0562 Oslo 5, Norway*
Netherlands Organization for Scientific Research (NWO), the Free University, N-1007 MC Amsterdam, The Netherlands
*Present address: Nordic Volcanological Institute, University of Iceland, Geoscience Building, 101 Reyk- javik, Iceland.

Abstract: The mildy peralkaline Eikeren-Skrim granite belongs to the Permian magmatic province of the Oslo rift, south-east Norway. Euhedral quartz crystals from the abundant miarolitic cavities contain primary inclusions of partly crytallized silicate melts and coexisting primary, aqueous fluid inclusions. Micro-thermometric measurements give maximum estimates for the granite solidus of 685–705°C. Quenched silicate melt inclusions are not peralkaline, have normative Or/Ab weight ratios of 1.15–1.44 (compared to 0.49–0.80 in whole-rock samples) and F and Cl contents of 0.1 and 0.21–0.65 wt. %, respectively. Coexisting magmatic fluid inclusions are highly enriched in Na, Cl, S and to some extent K. These chemical characteristics are the results of late-magmatic melt-mineral-fluid interaction in the miarolitic cavities.

Keywords: silicate melt inclusions • granite • peralkaline • Oslo rift • Norway

Mineralogical Magazine; June 1990 v. 54; no. 375; p. 195-205; DOI: 10.1180/minmag.1990.054.375.06
© 1990, The Mineralogical Society
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