Norsk versjon
	THE INDUSTRIAL MINERAL DATABASE
	Occurence 1806 - 336 Råna
	(Object Id: 15057) (Last updated: 26.02.2004)

Mineralization

	Genesis:		Form:
	Main texture:		Min. distribution:

Main grain size:

	Strike/Dip:		Direction:
			Plunge:

Stratigraphic classification of host rock

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	Tectonic complex:
	Igneous complex:

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Formation:

Bibliography:

From NGU's Reference Archive:

Foslie, Steinar , 1920

	III. Raana noritfelt. Differentiation ved "squeezing".

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.87;52 pages

Abstract:

Among the great masses of eruptive rocks, intruded during the period of Caledonain folding in the crystalline cambro-silurian sediments of northern Norway, the basic eruptives, although by far not so abundant as the granitic rocks, are specially of interest, as well from a petrographic as an economic point of view. The present paper deals with the Raana field of noritic intrusives, situated on the south side of the Ofoten fjord, west of the town of Narvik. In the very rugged country with heigh ht differences of more than 4000 feet, the whole mass is exceedingly well exposed, and the results of differentiation can be followed in all details. In the author's opinion this field examplifies excellently the importance of squeezing in certain differentiation processes during orogenic foldings. The eruptive mass occurs in a thick series of garnet-mica-schists with some leading horizons of marble. It is proved definitively, that the norite does not form an inverted syncline, but is injected at a certain horizon between the schists. Moreover, the way of intrusion has been parallel to the schistosity, and cross-cutting dikes of eruptive rocks have not been encountered in the whole district.

Boyd, Rognvald; Mathiesen, Carl O. , 1979

	The nickel mineralization of the Rana mafic intrusion, Nordland, Norway.

;TIDSSKRIFTARTIKKEL;Canadian mineralogist; No.17 (Part 2);287-298 pages

Abstract:

The Råna synorogenic Caledonide intrusion in north Norway contains one known nickel deposit of significance, Bruvann. The mineralization consists of pyrrohotite + pentlandite + chalcopyrite + pyrite, occurring interstitially to to olivine and orthopyroxene in peridotite and grading up to 0.8% sulfide nickel. Locally, associated with certain deformation zones, interstitial sulfide dissemination passes into massive mobilized sulfide with up to 5% nickel. Reserves are 43 million metric tons with 0.33% sulfide nickel, 0.08% copper and approximately 0.015% cobalt. The Råna intrusion consists of a peripheral zone of norite containing bands and lenses of peridotite and pyroxenite, and a core mainly of quartz norite. The Råna mass thus has a gross stratigraphy that conforms to the pattern of many layered intrusions, but, over much of the intrusions, primary structures have been disturbed by the later Caledonian fold phases which also involved local overthrusting; these movements resulted in an infolding and thrusting of units of semipelitic and calc-silicate gneiss and black schist into the intrusion. The body has the form of an inverted, possibly truncated cone with its axis plunging north- westward at a moderate angle. There are problems in placing the Råna intrusion within existing classifications of mafic intrusions. The peridotites show no obvious systematic variation of sulfide or silicate mineralogy across strike. The presence of sulfide-bearing black schists on or close to the contacts of the intrusion and emplaced within it along shear zones and the occurrence of graphite within sulfide disseminated in peridotite suggest assimilation of sulfur from the country rocks. Sulfur isotope studies do not, however, offer confirmation of the hypothesis that an external source of sulfur has had more than very local significance in Råna.

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The fact sheet was created on 29.04.2024

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