Norsk versjon
	THE ORE DATABASE
	Occurence 5022 - 015 Bjørkåsen
	(Object Id: 4278) (Last updated: 01.07.1998)

Operations

	From - To	Activity	Comments
	1997 - 1997	Sampling	Company/Institution :NGU-Malmreg.

Mineralization

	Genesis:	Sedex	Form:
	Main texture:	Banded	Min. distribution:	Semi-massive (20-50 % ore minerals)

Main grain size:

Fine grained (< 1 mm)

Main alteration:

	Strike/Dip:		Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Period:

	Province:	Caledonides
	Geotec.unit:	Trondheim Nappe Complex
	Tectonic complex:	Gula Nappe
	Igneous complex:

Group:

Gula

Formation:

Undal

Mineralogy

	Relationship	Mineral	Amount
	Gangue mineral	Biotite	Major mineral (>10%)
	Gangue mineral	Quartz	Major mineral (>10%)
	Gangue mineral	Chlorite	Major mineral (>10%)
	Gangue mineral	Graphite	Major mineral (>10%)
	Ore mineral	Pyrrhotite	Major mineral (>10%)
	Ore mineral	Pyrite	Subordinate mineral (1-10%)
	Ore mineral	Sphalerite	Accessory mineral (<1%)
	Ore mineral	Chalcopyrite	Accessory mineral (<1%)
	Ore mineral	Arsenopyrite	Accessory mineral (<1%)

Lithology:

	Relationship	Rock	Origin
	Host rock	Black schist	Sedimentary Original rock :Bituminous silty mudstone
			Metamorphic facies :Greenschist
	Wall rock	Carbonaceous grey-green schist	Sedimentary Original rock :Tuffite
			Metamorphic facies :Greenschist
	Wall rock	Quartzite	Sedimentary Original rock :Sandstone
			Metamorphic facies :Greenschist

Structures

	Location:	Type:	Orientation(360 gr.):	Relation to min.:
	Host rock	Fold axis	Dir./Plunge :140 / 35
	Host rock	Mineral lineation	Dir./Plunge :140 / 35	Post-mineralisation ;...Effect :None

Information(s) in free text format

Description

Det lille skjerpet (av Lindberg (1971) kalt Igle grube) ligger like ved bekken i en liten bekkedal sør for Bjørkåsgrenda. I skjerpet ses ca. 1 m (?) mektig finbåndet, semimassiv magnetkis-svovelkis-mineralisering med spor av kobberkis i svartskifer (prøve 01). Kisen opptrer stedvis som breksjerte, meget finkornige aggregater av magnetkis og svovelkis, sementert av grovere slirer og bånd av samme. Magnetkisen kan være anriket i bånd av opptil noen få cm mektighet. På liggsiden av den semimassive mineraliseringen er det kvartsitt med relativt sterk magnetkis-impregnasjon (prøve 02). Samlet mineralisert mektighet er minst 2 m (kan være mer - dårlig avblotning). Skiferen er sterkt foldet etter akse 140/35. I mineraliseringens ligg er det kvartsitt, mens det i blotninger over og under (et stykke fra) er det karbonatholdig grågrønn skifer. Mineraliseringen er ikke funnet blottet utenfor skjerpet.

Bibliography:

From NGU's Reference Archive:

Nilsen, Odd , 1978

	Caledonian sulphide deposits and minor iron-formations from the southern Trondheim region, Norway.

;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU; No.340;35-85 + k pages

Abstract:

Within the southern and central parts of the Trondheim region of the Norwegian Caledonides a great number of small, stratabound cupriferous pyrite deposits are confined to mafic metavolcanics of the Gula, Støren and Fundsjø Groups of the Lower Palaeozoic succession. The deposits occuring within, or in close contact with the metavolcanics are characterized by their association with minor manganiferous oxide/silicate iron-formations - better known as "vasskis" ore type - within the metamorphic low-grade areas. The iron-fprmations of the metamorphic higher grade terrains on the other hand, which are extensively developed within the Gula Group, are mostly of a pyrrhotitic sulphide/silicate type and sulphurization processes are thought to have played an important role during the metamorphism. The pyrite deposits occurring adjacent to the metavolcanics bear no relationship to the iron-formations. They are embedded in pelitic, often carbonaceous assemblages (Gula Group) or within tuffitic members of the volcanogene Støren Group, and they are thought to represent re-sedimented (reworked) deposits. The pyrite deposits display varying degree of metamorphic reconstitution and a tectonic control has apparently determined their disc- or ruler-shaped morphology.

Lindberg, Per Aksel , 1971

	En geologisk og petrografisk undersøkelse med malmgeologiske betraktninger i området Berkåk - Soknedal, Sør-Trøndelag.

;UiO Geografisk inst.;AVHANDLING

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

Nilsen, O. & Rohr-Torp, E. 1976: Rapport fra malmgeologiske undersøkelser i Rennebu sommeren 1976. BV 3913.

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	ST0075.01	Dump	Sampler: Wilberg/...Stored: Løkken Comment: Semimassiv po-min. i svartskifer No. of registrated element analyses = 1
	ST0075.02	Dump	Sampler: Wilberg/...Stored: Løkken Comment: Kvartsitt med po-diss. No. of registrated element analyses = 1

NB! All analyse values are shown at the end of the printout.:

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Analyse Results

from

Deposit Area 5022 - 015 Bjørkåsen

Element analyses

( *=parts pr. million, #=parts pr.billion, Negative values means below detection limit value.)

Sample No.	Sample Type	Cu*	Zn*	Pb*	Co*	Ni*	Ag*	Au#
ST0075.01	Dump	285	103	34	28	171	2.0	30.0
ST0075.02	Dump	152	69	7	3	17	-.3	-1.0

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Sample No.	Pt#	Pd#	As*	Cd*	Ba*	Mo*	Sb*	Bi*	S%
ST0075.01	7.0	4.0	92	3.7	26	24.00	-3	9	27.30
ST0075.02	1.0	-1.0	51	.6	10	3.00	-3	-3	2.39

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Sample No.	V*	Cr*	Mn*	Fe%	Th*	U*	W*	Sr*	La*
ST0075.01	207	20	356	53.85	12.00	-8.00	-2	5.0	6.00
ST0075.02	24	23	136	4.31	-2.00	-8.00	12	2.0	1.00

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Sample No.	B*
ST0075.01	-3
ST0075.02	-3

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The fact sheet was created on 28.04.2024

Questions or comments regarding the fact sheet can be emailed to: ressursdatabaser@ngu.no

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