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	INDUSTRIMINERALDATABASEN
	Forekomstområde 1112 - 302
	(Sist oppdatert 14.okt.2024)

Betydning

Offentlig:

Internasjonal betydning (reg. 20.05.2015)

Økonomisk:

Meget viktig , (Stadfestet 23.jan.2013 av Havard Gautneb)

Produkt

	Element/produkt	Gehalt/Kvalitet
	APATIT	%

Mineralisering

	Æra:	Proterozoikum	Periode:	Neoproterosoikum
	Datering:		Metode:
	Genese:	Dypbergart	Form:	Lag
	Hovedtextur:	Skifrig	Min. fordeling:	Disseminert

Kornstørrelse:

	Strøk/Fall:		Retning:
			Feltstupning:

Stratigrafisk klassifikasjon av vertsbergart

Æra:

Periode:

	Provins:
	Geotek.enhet:
	Tektonisk complex:
	Intrusivt komplex:	Egersundanortosittkomplekset

Gruppe:

Formasjon:

Opplysning(er) i fritekstformat

Sammendrag

Oxide- and apatite-rich modally layered gabbronorite in the Bjerkreim-Sokndal Layered Intrusion in the Rogaland Anorthosite Province. The stratigraphic sequence, to wich the Teksevatnet-Lauvneset deposit belongs, is conventionally denoted MCU4-e and may be followed along strike from Rappstad in the southern extension around the hinge of the Bjerkreim lobe to Heskestad in the northeastern extension - a total distance of approximately 25 km. The thickness of the zone is variable, both stratigraphically and in exposure, decreasing from up to 2000 m in the central most part to around 500 m on the flanks. The economic part of this zone forms a 10 km long and 50 m to 170 m thick zone from the Terland area to the Ualand area. A persistent melanocratic inteval at the base of MCU IVe has been documented through 9 surface sampling profiles and two short drill holes Currently, apatite has to be considered the prime commodity with ilmenite and vanadian magnetite as important bi-products. At Lauvneset the thickness of MCU IVe is in the order of 500 m. The economic part has a thickness of approximately 80m. The mineralised zone of MCU IVe has been surveyed through 9 surface sampling profiles and two short drill holes by lito rigg. This leads to the following assessment: Resource area : 30 – 90 m x 8500 m, eq. 250000 - 700000 m2 Average value mineral content : Apatite: 10 % Ilmenite: 14 % Magnetite: 8 % MgO (in ilmenite): 1.0-1.8 % V2O3 (in magnetite): 0.90 Assumed continuity to a depth of 100 m gives a resource base of around 190 Mt Grades may be increased by further constraining width or length of deposit area.

Litteraturfortegnelser:

Fra NGU's Referansearkiv.:

Duchesne, Jean-Clair ; Auwera, Jacqueline Vander , 2003

	Fe-Ti-V-P deposits in anorthosite complexes: the bearing of parental magma composition and crystallization conditions on the economic value.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;Special publication; No.9;60-61 sider

Gautneb, Håvard , 2003

	SEM elemental mapping and characterisation of ilmenite, magnetite and apatite from the Bjerkreim-Sokndal layered intrusion.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;Special publication; No.9;65-68 sider

Korneliussen, A.; Furuhaug, L.; Gautneb, H.; McEnroe, S.; Nilsson, L.P.; Sørdal, T. , 2001

	Forekomster med ilmenitt, vanadiumholdig magnetitt og apatitt i norittiske bergarter i Egersundfeltet, Rogaland

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.2001.014;29 sider

Abstrakt:

Ved tidligere undersøkelser er det påvist at norittiske bergarter i omrpåden Sokndal og Bjerkreim inneholder betydelige mengder av apatitt, ilmenitt og vanadiumholdig magnetitt, men at forekomstene er lavgehaltige. En rekke norittrelaterte forekomster inneholder i størrelsesorden 10% apatitt, 10% ilmenitt og 10% magnetitt. De minerallogiske kvaliteter synes å være gode. For eksempel forekommer ilmenitt med relativt lavt MgO-innhold (i størrelsesorden 1%) og magnetitt med høyt V-innhold (0.7-1.2% V2O2) sammen med C1-fattig apatitt i visse deler av området, noe som er positivt med tanke på mulighetene for framtidig gruvedrift. Samtidig er de samlede ressurser av kombinert apatitt ilmenitt og vanadiumrik magnetitt store. Og det burde være rimelig gode muligheter til å påvise nye forekomster med minst like gode kvaliteter som de som er påvist fram til nå.

Wilson, J. R.; Robins, B.; Nielsen, F. M.; Duchesne, J. C.; Auwera, J. Vander , 1996

	The Bjerkreim-Sokndal layered intrusion, Southwest Norway.

;Elsevier Science;ARTIKKEL;Layered intrusions; R.G. Cawthorne (editor);231-255 sider

Abstrakt:

The Bjerkreim-Sokndal Layered Intrusion is a large (-230 km²), discordant, Late Proterozoic, post-orogenic pluton in the Egersund-Farsund Igneous Province. The intrusion was emplaced shortly after massif-type anorthosite plutons and is cut by jotunite dykes. It contains a >7000 m thick Layered Series consisting of rocks belonging to the anorthosite kindred: andesine anorthosite, leuconorite, troctolite, norite, gabbronorite, mangerite, and quartz mangerite. Cumulates in the Layered Series are organized in 6 megacyclic units (MCU 0 to IV), individually up to 1800 m thick, but varying considerably in thickness and development along strike. The highest-temperature cumulates are troctolites containing plagioclase of ~An54 and olivine of ~Fo77. Phase contacts in the macrocyclic units reflect crystallization of the silicate minerals in the order plagioclase (± olivine), orthopyroxene, Ca-rich pyroxene, pigeonite. Ilmenite crystallized early and apatite appeared as a cumulus mineral at about the same time as Ca-rich pyroxene. Cumulus magnetite followed orthopyroxene and preceded Ca-rich pyroxene in MCU III and IV, but crystallized after Ca-rich pyroxene in MCU IB. MCUs 0, IA, and II do not contain cumulates with cumulus magnetite or Ca-rich pyroxene. Olivine (~Fo50) reappears in the uppermost part of the Layered Series where there is a rapid stratigraphic transition to mangerite and quartz mangerite. The basal parts of MCUs III and IV are characterized by thin sequences of plagioclase, plagioclase-orthopyroxene-ilmenite and orthopyroxene-ilmeinte cumulates in which there are systematic upward decreases in initial Sr isotope ratios. They are overlain by tractolite (plagioclase-olivine cumulate) and are believed to have crystallized from hybrid magmas. (...)

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Faktaarket ble generert 22.11.2024

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