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	THE ORE DATABASE
	Occurence 625 - 019 Glitrevatnet
	(Object Id: 0625,019,00,00) (Last updated: 13.12.2023)

Mineralization

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According to Schønwandt (1986) the most interesting molybdenite mineralization within the Glitrevann caldera is hosted by the Bordvika ignimbrite where molybdenite occurs in a mineralized stock-work associated with sericite alteration. Along the southeastern shore of Bordvika, molybdenite occur in mineralized fractures and associated sericite alternating in Bordvika ignimbrite. The Bordvika ignimbrite appeas as a homogeneous quartz-feldspar porphyry with grey to black, aphanitic matrix. The feldspar and quartz phenocrysts constitute respectively about 30vol% and 10% vol% of the ignimbrite. Hydrothermal sericite alteration in the Bordvika area occurs in a stockwork-like pattern. This sericite alteration primarily occurs as envelopes along mineralized fractures. In the most intensely altered areas the envelopes can be more than 1 m wide, although generally theyu are in dm-cm range. The sericite altered ignimbrite is white to grey and consists of sericite, quartz and pyrite. The alteration process has destroyed most of the primary textures although quartz appear largely unaffected. The mineralized fractues show mineral assemblages comprising quartz, molybdenite, pyrite, magnetite and alkali-feldspar. The sericite enveloped fractues are cut by several types of mineralized fractues which occur without any visible alteration envelopes. Mineral assemblages of these include: 1) molybdenite-quartz-pyrite 2) pyrite 3) quartz-alkalifeldspar-molybdenite-pyrite. The presence of both altered and unaltered mineralized fractures indicates that at least two molybdenite mineralization events have occured in the stockwork alteration zone. Schønwandt (1986) interprets the molybdenite occurence at Bordvika as a mineralization formed by fumaroclic activity during degassing and welding of the ignimbrite.

Bibliography:

From NGU's Reference Archive:

Meisfjord, Norodd , 1987

	Diamantboring Glitrevann, Drammensmarka

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.87.030;34 pages

Jensen, Inger Spangsberg , 1985

	Geochemistry of the central granitic stock in the Glitrevann cauldron within the Oslo rift, Norway.

;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.65 (3);201-216 pages

Abstract:

Frie emneord: Stokk (Pluton) The central granitic stock within the Glitrevann cauldron comprises three main granitic types, of which the youngest one, an aplitic granite, is associated with significant porphyri-Mo mineralizations. A mineralogical and geochemical differentiation is developed from the older granite types towards this aplitic granite. Quantitative trace element modelling, based on crystal fraction using petrographic mixing calculations relating three main compositions, suggests that the aplitic granite represents a fractionated residual fluid phase, giving rise to the mineralizations.

Bjerkgård, Terje; Ihlen, Peter M.; Sandstad, Jan Sverre , 2016

	De viktigste mineralressursområdene i Buskerud

;Norges geologiske undersøkelse;RAPPORT;NGU-rapport; No.2016.013;20 pages

Abstract:

Inntil nå har de aller fleste av Norges mineralressurser kun vært punktfestet, dvs. uten et definert areal. De har også i liten grad vært verdisatt, dvs. i hvilken grad de er viktige ressurser. Dette er problematisk i forhold til f.eks. kommuneplaner, verneplaner, veiplaner osv. Viktige økonomiske forekomster og områder med et høyt potensial for å finne drivverdige forekomster kan bli båndlagt ved annen aktivitet/utbygging/fredning osv. Det er derfor besluttet at ressursene skal verdisettes og omsluttes av arealer i henhold til standardiserte kriterier.

References not to be found in NGU's Reference Archive.:

Schønwandt, H. K. (1986) The volcanic history and the molybdenite mineralization of the Glitrevann caldera. In Olerud, S. & Ihlen (editors) (1986) Metallogeny associated with the Oslo Paleorift. 7th IAGOD symposium and Nordkalott project meeting. Excusion guide no 1. SGU.

Geyti, A. & Scønwandt, H.C. 1979. A possible porphyry molybdenum occurrence within the Oslo Rift, Norway. Economic Geology, Vol. 74, 1211-1220.

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The fact sheet was created on 23.04.2024

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