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Some aspects of the geochemistry and petrology of the Precambrian Homme granite in the Flekkefjord area, southern Norway

1976; Taylor & Francis; Volume: 98; Issue: 2 Linguagem: Inglês

10.1080/11035897609454355

0016-786X

Torgeir Falkum,

High-pressure geophysics and materials

Abstract The Homme gneissic granite is a deformed and metamorphosed intrusion situated in a banded gneiss—migmatite area. The pluton is relatively homogeneous, with only a few small inclusions, which are mostly confined to two zones near the discordant northern and southern boundaries, together with a zone running east—west in the central part. Assimilation of the different inclusions is believed to have influenced the element distribution within the pluton. Trend-surface analyses of the major elements reveal a consistent pattern, which is interpreted as being due partly to magmatic differentiation and partly to assimilation of inclusions. It is suggested that the SiO2-and K2O-rich zones towards the discordant contacts are the result of assimilation by more or less selective melting of country-rock xenoliths. Extreme biotite-rich inclusions are interpreted as residuals after this anatexis. The granite magma was probably derived by partial melting at considerable depth in a geotectonic belt with magmatic activity.