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	INDUSTRIMINERALDATABASEN
	Registrering 1806 - 305 Tverrfjellet
	(Objekt Id: 7588) (Sist oppdatert: 26.02.2004)

Mineralisering

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For å komme til forekomsten tar en av fra Råna på E6 og kjører ca. 10 km langs Storvatnet til Rånvassbotn. Enkleste adkomst til forekomsten derfra er å gå opp til Tverrfjellet i bratt lende. Avstanden opp er ca. 2 km, bratt og uten sti. Forekomsten består av en hovedlinse med areal på utgående som er oppgitt. I tillegg finnes flere kropper og lag med ultramafitt fra en relativt godt bevart kumulatsekvens. Det er gjort detaljerte undersøkelser i området med henblikk på platina, palladium og gull i bergartene.

Litteraturfortegnelser:

Fra NGU's Referansearkiv.:

Barnes, Sarah-Jane , 1986

	Investigation of the potential of the Tverrfjell portion of the Råna intrusion for platinum group element mineralization

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.86.201;169 sider

Abstrakt:

En betydelig likhet i krystallisasjonsrekkefølge og mineralkjemi mellom Råna-intrusjonen og Bushveld-intrusjonen (Sør-Afrika), som er verdens viktigste platina-kilde, ledet til den tanke at det kunne være en mulighet for en Marensky Reef type platinaforekomst i Tverrfjellet-delen av Råna- intrusjonen. Etter en petrologisk og kjemisk undersøkelse er konklusjonen at Tverrfjell- delen av intrusjonen ikke inneholder noen platina-forekomst, og at muligheten for en slik forekomst andre steder i intrusjonen er svært liten. En sannsynlig forklaring på det lave innholdet av platina og andre edelmetal- ler i intrusjonen er at edelmetallene har vært oppløst i en sulfidfase som ble fjernet fra primær-magmaet før dannelse av de magmapulsene som formet de til- gjengelige deler av intrusjonen. Magmapulsene har derfor hatt et for lavt platina-innhold til å kunne danne en forekomst, selv om gunstige oppkonsentra- sjons-mekanismer kan ha vært aktive i Tverrfjellet.

Barnes, Sarah-Jane , 1987

	Unusual nickel and copper to noble-metal ratios from the Råna Layered Intrusion, northern Norway.

;Norsk geologisk forening;TIDSSKRIFTARTIKKEL;Norsk geologisk tidsskrift; No.67 (3);215-231 sider

Abstrakt:

Rocks from the Råna Layered Intrusion usually have low concentrations of noble metals but have normal Ni and Cu concentrations. Consequently the rocks have higher Cu/Ir, Ni/Ir, Cu/Pd and Ni/Pd ratios than extrusive rocks from the literature. If a small amount of sulphide was removed from the magma prior to its emplacement at Råna the magma would be deplected in noble metals relative to Ni and Cu, and rocks forming from it would have high Ni and Cu to noble-metal ratios.

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 sider

Abstrakt:

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.

Foslie, Steinar , 1920

	III. Raana noritfelt. Differentiation ved "squeezing".

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

Abstrakt:

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.

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