Norsk versjon
	THE INDUSTRIAL MINERAL DATABASE
	Occurence 5601 - 301 Melkevann
	(Object Id: 7019) (Last updated: 17.04.2015)

Mineralization

	Genesis:		Form:
	Main texture:		Min. distribution:

Main grain size:

	Strike/Dip:		Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Period:

	Province:
	Geotec.unit:
	Tectonic complex:
	Igneous complex:

Group:

Formation:

Mineralogy

	Mineral	Amount
	Olivine	Major mineral (>10%)
	Hornblende	Subordinate mineral (1-10%)
	Serpentine	Subordinate mineral (1-10%)
	Pyroxene	Subordinate mineral (1-10%)

Information(s) in free text format

Free text

Seiland. Dunitt med 90-95% svakt serpentinisert olivin, resten pyroksen og hornblende. Dette er det beste området innen den store olivinførende peridotitten mellom Vargsundet og Store Kufjord. Kropper med opptil 200m mektighet opptrer. Olivinen har for høyt jerninnhold (Fo 80).

Bibliography:

From NGU's Reference Archive:

Bennett, M.C.; Emblin, S.R.; Robins, B.; Yeo, W.J.A. , 1986

	High-temperature ultramafic complexes in the North Norwegian Caledonides: I - Regional setting and field relationships.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU Bulletin; No.405;1-40 pages

Abstract:

Forkortet. Four major (25-100 km²) ultramafic complexes were developed in the Sørøy Nappe during the second phase of Finnmarkian deformation in the North Norwegian Caledonides. They were emplaced into layered mafic intrusions and show broadly similar emplacement histories and petrographic variations suggesting a related petrogenesis. The Nordre Bumannsfjord, Melkvann and Kvafjord group of ultramafic complexes developed in part by emplacement of both replacive and dilational ne-normative ultramafic sheets and dykes which progressively fragmented the layered olivine gabbro envelope. The Reinfjord ultramafic complex contains pronounced, subhorizontal modal layering and evidence of at least 3 major magmatic events. The intrusive sequences and petrographic variations represented in the complexes suggest the succesive emplacement of mantle-derived magmas with a diminishing number of liquidus phases, accompanied by in situ liquid-crystal fractionation, subsidiary hybridization and metasomatism.

Oosterom, M.G. , 1954

	En hornblenderik sone i Seiland-peridotitten. Foreløbig meddelelse.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.188;51-53 pages

Abstract:

A hornblende-rich zone in the peridotite of Seiland: In the island of Seiland the presence of an extensive peridotite mass was known from earlier investigations. This rock proved to be of a varying mineral composition, the more common type being hornblende-pyroxene-peridotite. As shown on the map, a zone of hornblende-rich rock crosses the peridotite mass. This rock has about 50 percent hornblende, the rest being olivine and pyroxene. There are poikilitic inclusions of olivine and pyroxene in the large hornblende crystals and there are pocket-like inclusions of peridotite in the hornblende- rich rock. The impression was gained that the hornblende-rich rock was formed by metasomatic alteration of the peridotite in a tectonic zone of weakness.

Oosterom, M.G. , 1963

	The ultramafites and layered gabbro sequences in the granulite facies rocks on Stjernøy.

;AVHANDLING;296 s. pages

Abstract:

På Stjernøy, Seiland og på fastlandet ved Øksfjord og Bergsfjord finne peridotitt, pyroksenitt og lagdelt gabbro innenfor et kompleks av høymetamorfte gabbro gneisser. Den lagdelte gabbro er i alminnelighet konkordant med parallellstrukturen i de omliggende gneiser, men viser lokalt uregelmessigheter (se kart i lommen bak i boken). Også hornblenditt, karbonatitt og nefelinsyenitt forekommer, de er sannsynligvis dannet ved metasomatiske prosesser. (Forkortet)

Roberts, David , 1974

	Hammerfest. Beskrivelse til det 1:250 000 berggrunnsgeologiske kart. (Med geologisk og aeromagnetisk kart)

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL; KARTBESKRIVELSE;NGU; Skrifter; No.301; 10;1-66 + ka pages

Abstract:

General descriptions of the different metasediments, metavolcanics and igneous rocks within the map area are presented. Three principal map-subdivisions are recognized; (a) supracrustal Precambrian (Karelian) rocks occurring in tectonic Windiws; (b) autochthonous late Precambrian to Lower Cambrian (meta)sediments; and (c) a thick allochthonous nappe-complex od Eocambrian to Cambrian metasediments, gneisses and various igneous rocks. In addition to these lithologies, sediments of unknown age (but possibly Silurian) lying unconformably upon allochthonous gneisses are noted from the south-western corner of the map-sheet. Descriptions are given of the many types of plutonic rocks occurring within the Seiland-Stjernøy petrographic province. These include several varieties of gabbro as well as diorites, peridotites, syenite, nepheline syenite, hornblendite, carbonatite, anorthosite, trondhjemite and adamellite. The major tectonic structural subdivisions of the map-area are outlined and it is shown that the matamorphic lithologies of the allochthon, here referred to as the Kalak nappe-complex, can be readily separated into three main tectonic units, or nappes.

Oosterom, M.G. , 1954

	En hornblenderik sone i Seiland-peridotitten. Foreløbig meddelelse.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.188;51-53 pages

Abstract:

A hornblende-rich zone in the peridotite of Seiland: In the island of Seiland the presence of an extensive peridotite mass was known from earlier investigations. This rock proved to be of a varying mineral composition, the more common type being hornblende-pyroxene-peridotite. As shown on the map, a zone of hornblende-rich rock crosses the peridotite mass. This rock has about 50 percent hornblende, the rest being olivine and pyroxene. There are poikilitic inclusions of olivine and pyroxene in the large hornblende crystals and there are pocket-like inclusions of peridotite in the hornblende- rich rock. The impression was gained that the hornblende-rich rock was formed by metasomatic alteration of the peridotite in a tectonic zone of weakness.

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

Yeo, H.S., Jr. 1984: The Melkevann Ultramafic Complex, Seiland igneous province, North Norway: Intrusive mecanisms and petrological evolution. Unpubl. Ph.D. thesis, Univ. of Bristol, U.K.

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