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	THE ORE DATABASE
	Deposit Area 1924 - 019
	(Last updated 07.mar.2017)

Importance

Public:

Little Importance (reg. 02.06.2015)

Economical:

Minor interest , (Confirmed 02.jun.2015 by Terje Bjerkgård)

Operations

	From - To	Activity	Comments
	2011 - 2011	Geophysics	Company/Institution :NGU
			Aerial survey (mag., EM, radiometry)
	2011 - 2013	Geology	Company/Institution :NGU

Mineralization

	Era:	Proterozoic	Period:	Mesoproterozoic
	Dating:		Method:
	Genesis:	Chemical sediment	Form:	Lens
	Main texture:	Banded	Min. distribution:	Semi-massive (20-50 % ore minerals)

Main grain size:

Medium grained (1-3 mm)

Main alteration:

No country rock alteration

	Strike/Dip:		Direction:
			Plunge:

Stratigraphic classification of host rock

Era:

Proterozoic

Period:

Mesoproterozoic

	Province:	Troms-Finnmark Basement Province
	Geotec.unit:
	Tectonic complex:	Mauken Tectoni Window
	Igneous complex:

Group:

Målselva Group

Formation:

Myrefjellet Formation

Mineralogy

	Relationship	Mineral	Amount
	Gangue mineral	Carbonate	Major mineral (>10%)
	Gangue mineral	Grunerite	Major mineral (>10%)
	Gangue mineral	Quartz	Major mineral (>10%)
	Gangue mineral	Biotite	Subordinate mineral (1-10%)
	Gangue mineral	Chlorite	Accessory mineral (<1%)
	Ore mineral	Magnetite	Major mineral (>10%)
	Ore mineral	Pyrite	Accessory mineral (<1%)

Lithology:

	Relationship	Rock	Origin
	Wall rock	Greenschist/tuffite	Sedimentary Original rock :Tuffite
			Metamorphic facies :Greenschist
	Wall rock	Greenstone	Extrusive Original rock :Basalt
			Metamorphic facies :Greenschist

Information(s) in free text format

Free text

The iron formation is exposed in the pronounced Bjelma valley to the west of Myrefjellet. This valley (with the Bjelma stream), marks the boundary between the banded, tuffitic greenschist and the generally massive greenstone/ metabasalt. It gives a well-defined magnetic anomaly. The iron formation is located in the northwestern part of this valley, in the extension of a layer of calc-brecciated greenstone. It has a length of at least 700 m and a thickness of up to 30 m close to the major bend of the Bjelma stream. The iron formation varies in composition across strike, from quartz- to carbonate-rich. The carbonate is generally a brown, Fe-rich calcite or ankerite. Fine-grained magnetite is present in thin bands throughout the formation, generally the thin bands are found in zones less than one meter in thickness. Some zones in the formation are enriched in sulfides, mainly pyrite. One sample analyzed of the carbonate-rich part contains 25.5 % Fe2O3, 0.07 % TiO2 and 0.18 % P2O5, and one quartz-rich sample contains 33.0 % Fe2O3, 0.03 % TiO2 and 0.14 % P2O5. A 5-20 m thick layer of banded to laminated schist quite strongly enriched in magnetite is present in the banded greenschist some meters from the boundary to the greenstone. The unit contains bands with 2-4 % magnetite (measurements by handheld susceptibility meter. The unit can be followed for more than 1 km along strike. It is possible that this unit somehow is related to the iron formation.

Bibliography:

From NGU's Reference Archive:

Bjerkgård, Terje; Henderson, Iain; Sandstad, Jan Sverre; Schönenberger, Johannes; Slagstad, Trond , 2015

	Geology of the Mauken tectonic window, Målselv, Troms

;Norges geologiske undersøkelse;RAPPORT;NGU-rapport; No.2015.013;60+kart pages

Abstract:

This report presents the results from bedrock mapping in the Mauken tectonic window, carried out in several periods in 2011-2013. During the NGU MINN program, the Mauken area has been subject to a high-resolution airborne geophysical survey (magnetometry, radiometry, EM), followed by bedrock mapping and structural geology investigations. The work in the Mauken area is part of a larger project in southern Troms, with the goal to work out a structural-tectonic-metallogenic model and interpretaion for the basement areas in the whole region.

Fieldsamples

	Sample No.	Sample type	Miscellanrous
	TBMA_5	Bedrock	Sampler :T. Bjerkgård/...Stored :Løkken Comment :Carbonate-banded iron formation No. of registrated element analyses = 1
	TBMA_72	Bedrock	Sampler :T. Bjerkgård/...Stored :Løkken Comment :Quartz-banded iron formation 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 1924 - 019 Bjelma

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#
TBMA_5	Bedrock	158	25	-3	30	27
TBMA_72	Bedrock	337	8	2	12	18	.6	5.4

------------------

Sample No.	As*	Cd*	Ba*	Mo*	Sb*	Bi*	Se*	Ga*	Ge*
TBMA_5			126	3.00				2.00	2.00
TBMA_72	2	-1.0	31	-1.00	1	-1	-1.00	1.00

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Sample No.	S%	V*	Cr*	Mn*	Fe%	Th*	U*	W*	Rb*
TBMA_5		44	45	9217	17.83	-4.00	-2.00	-5	3.0
TBMA_72	-.02	18	44	3330	23.06	-1.00	-1.00	2	4.0

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Sample No.	Sr*	Y*	Zr*	Nb*	Ta*	Cs*	La*	Ce*	Pr*
TBMA_5	12.0	17.0	19	2.00	-4.00	-10.00	-20.00	90.00
TBMA_72	5.0	13.0	14	-1.00	-1.00	-1.00	9.00	21.00	2.00

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Sample No.	Nd*	Sm*	Eu*	Gd*	Tb*	Dy*	Ho*	Er*	Tm*
TBMA_5	21.00	14.00
TBMA_72	9.00	2.00	-1.00	2.00	-1.00	2.00	-1.00	1.00	-1.00

------------------

Sample No.	Yb*	Lu*	Na*	Mg*	Al*	Si*	P*	K *	Ca*
TBMA_5	-5.00		371	15316	6827	######	790	1312	13508
TBMA_72	1.00	-1.00	37	3377	3493	######	611	249	3359

------------------

Sample No.	Sc*	Ti*	Hf*	Hg*
TBMA_5	5.00	396	-5.00
TBMA_72		180	-1.00	-1

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The fact sheet was created on 10.05.2024

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

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