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	MALMDATABASEN
	Forekomstområde 2030 - 023
	(Sist oppdatert 01.mar.2005)

Betydning

Offentlig:

Ikke vurdert (reg. 20.03.2017)

Økonomisk:

Kan være viktig , (Stadfestet 15.feb.2005 av Peter Ihlen)

Operasjoner

	Fra - Til	Aktivitet	Kommentar
	1993	Geologi	Selskap/Institusjon:NGU
	1995 - 1996	Geofysikk	Selskap/Institusjon:NGU
	1996	Kjerneboring	Selskap/Institusjon:NGU

Mineralisering

	Æra:	Proterozoikum	Periode:	Paleoproterosoikum
	Datering:		Metode:
	Genese:	Skjærsone-mineralisering	Form:	Plate
	Hovedtextur:	Sprekkefylling	Min. fordeling:	Disseminert

Kornstørrelse:

Finkornet (<1 mm)

Hovedomvandling:

	Strøk/Fall:		Retning:
			Feltstupning:

Stratigrafisk klassifikasjon av vertsbergart

Æra:

Proterozoikum

Periode:

Paleoproterosoikum

	Provins:	Troms-Finnmark grunnfjellsprovins
	Geotek.enhet:	Polmak-Pasvikgrønnsteinsbeltet
	Tektonisk complex:	South Pechenga
	Intrusivt komplex:

Gruppe:

Langvann Group

Formasjon:

Mineralogi

	Relasjon	Mineral	Mengde
	Gangmineral	Kvarts	Hovedmineral (>10%)
	Gangmineral	Aktinolitt	Underordnet mineral (1-10%)
	Gangmineral	Plagioklas	Underordnet mineral (1-10%)
	Gangmineral	Grafitt	Underordnet mineral (1-10%)
	Gangmineral	Kalkspat	Underordnet mineral (1-10%)
	Malmmineral	Arsenkis	Hovedmineral (>10%)
	Malmmineral	Svovelkis	Hovedmineral (>10%)
	Malmmineral	Gull	Hovedmineral (>10%)
	Malmmineral	Kobberkis	Underordnet mineral (1-10%)
	Malmmineral	Magnetitt	Underordnet mineral (1-10%)
	Malmmineral	Magnetkis	Underordnet mineral (1-10%)

Opplysning(er) i fritekstformat

Fri tekst

In 1993 gold-bearing quartzite boulders assumed to represent true outcrops were discovered by NGU during regional geological investigations of the Paleoproterozoic Pasvik-Polmak Greenstone Belt (Melezhik, 1995). The discovery point is located on the southern shore of a small shallow lake which Melezhik (1995) termed Gjedde or Pike Lake since his discovery of arsenopyrite-rick quartz boulders was the result of an attempt to stone a big pike. However, on a recently published orienteering map the lake is designated Lake Støvlevann (1:15 000, "Sukkeråsen", I.L. Pasvik-Hauk/Sandnes I.L., 1995). Core drilling in 1996 including 12 DDH with a total length of 600 m over a strike length of 350 m, showed that the mineralised outcrops at the shore of the lake actually represent large blocks of the underlying bedrocks. The gold mineralisation is therefore totally covered by blocky till. Based on the results of magnetic and electromagnetic (IP, SP, VLF) ground-surveys it can be concluded that the mineralisation gives no clear response. Detailed geochemical surveys of tills and top-soils in the area around the lake gave only weak anomalies in the mineralised area, except for the area west of the lake where mineralised bedrocks subsequently have been found by drilling by Scannor. The Gjeddevann gold occurrence is located to the lower peripheral part of the South Pasvik Thrust Zone, a regional thrust zone along the upper margin of the Pasvik Greenstone Belt. The gold mineralisation is hosted by a strongly sheared and imbricated volcanic sequence with planar structures striking E-W and dipping 30°-45° south. The host rocks comprise various phyllonitic biotite-, hornblende- and/or chlorite-rich schists as well as amphibolites and thin tectonic lenses of fine-grained quartzites (£ 5m). The sequence has been affected by three regional scale deformational events (D1-D3). Progressive N-S shortening with associated folding and thrusting occurred during the D1 and D2 events, when the sequence was infiltrated by large volumes of hydrothermal fluids as indicated by the high density of discordant and foliation-concordant quartz±calcite veins/stringers as well as widespread silicification. Native gold and arsenopyrite were probably precipitated during the end of the D2 event and preferentially as dissemination both in the schists adjacent to concordant quartz veins and along their margins. Native gold forms 1-100mm grains, occurring mainly as inclusions and micro-veinlets in cataclastic arsenopyrite and more rarely as isolated grains interstitial to arsenopyrite, pyrrhotite and/or gangue minerals. High gold concentrations (>1g/t) are invariably restricted to areas containing visible arsenopyrite, which means the westernmost 50m of the drilled area, i.e. in DDH 2, 3, 4, 5, 8 and 9. All of these drill holes, except for DDH 4 and 8 (not analysed), contain 1m-sections with average grades in the range 1.3-6.3 g/t Au. Although the gold mineralisation is hosted by a number of different lithologies, the highest gold grades are encountered in the main grunerite quartzite of DDH 2 with a maximum of 14.7 g/t Au over 0.25m. This quartzite carries three 1m-sections averaging 2.9, 6.0 and 6.3 g/t Au or combined, 2.5 g/t Au over 3.25m. The gold grades and the length of mineralised sections are either too low or too short to be of any economic significance. However, the gold mineralisation may represent the eastern peripheral part of a auriferous hydrothermal system which may have its centre further west along strike.

Litteraturfortegnelser:

Fra NGU's Referansearkiv.:

Melezhik, Victor A. , 1995

	The Gjedde Lake gold occurrence in Pasvik

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.95.079;25 sider

Abstrakt:

The Gjedde Lake gold occurrence was found in the Pasvik Valley during field work in the summer of 1993. The area is poorly exposed and this hampered the investigation. The gold mineralisation is related to the upper section of the Early Proterozoic Petsamo Supergroup. The host rocks are represented by cherty quartzites, considered as chemical sediments related to submarine exhalations. The gold mineralistion is assosiated with the sulphide facies of the cherty quartzites, while the oxidised magnetite-bearing sulphide-free rocks do not contain any gold. The highest gold content is ca. 10 ppm. Detailed mapping of discovery site outcrops and limited sampling have been done. Further investigations are recommended, including ground geophysical survey (IP) and mapping of boulders and outcrops within an area of 0.5 km². Some trenching and core drilling are needed in this poorly exposed terrain.

Lauritsen, Torleif , 1996

	Ground VLF and magnetic surveys at the Gjedde Lake in Pasvik, Sør-Varanger, Finnmark, 1996

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.96.085;7 sider

Ihlen, Peter; Often, Morten; Braathen, Alvar , 1996

	Core drilling at Gjedde Lake and regional structural geological investigations in Pasvik, North Norway

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.96.145;68 sider

Finne, Tor Erik , 1997

	Evaluation of detailed C-horizon sampling as prospecting methods at Gjedde Lake gold mineralisation

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.97.172;52 sider

Braathen, Alvar , 1997

	Results from a structural study in Pasvik, North Norway

;Norges geologiske undersøkelse;FAGRAPPORT;NGU-rapport; No.97.018;31 sider

Abstrakt:

This report describes results from structural investigations undertaken in Pasvik in l996. The Early Proterozoic rocks of the Pasvik (Petsamo) and Kobbefoss Groups, and Archaean gneisses were deformed during three ductile to semiductile stages, designated D1, D2 and D3. Typical structures such as foliation, cleavage, lineations and folds support the structural sub- division, and place constraints on the structural position of the Gjedde Lake gold occurrence.

Feltprøver

	Prøvenr.	Prøvetype	Diverse
	SP-30	Løsblokk	Prøvetaker :Melezhik, V. Kommentar :Sulphide-bearing grunerite quartzite Antall registrerte elementanalyser = 1
	SP-33	Fastfjell	Prøvetaker :Melezhik, V. Kommentar :Sulphide-bearing grunerite quartzite Antall registrerte elementanalyser = 1
	93/1	Fastfjell	Prøvetaker :Melezhik, V. Kommentar :Sulphide-bearing grunerite quartzite Antall registrerte elementanalyser = 1
	93/3	Løsblokk	Prøvetaker :Melezhik, V. Kommentar :Sulphide-bearing grunerite quartzite Antall registrerte elementanalyser = 1
	93/4	Løsblokk	Prøvetaker :Melezhik, V. Kommentar :Sulphide-bearing grunerite quartzite Antall registrerte elementanalyser = 1
	93/5	Løsblokk	Prøvetaker :Melezhik, V. Kommentar :Sulphide-bearing grunerite quartzite Antall registrerte elementanalyser = 1
	93/6	Løsblokk	Prøvetaker :Melezhik, V. Kommentar :Sulfidførende kvartsitt Antall registrerte elementanalyser = 1
	93/6-1	Løsblokk	Prøvetaker :Melezhik, V. Kommentar :Sulfidførende kvartsitt Antall registrerte elementanalyser = 1

NB! Alle analyseverdier er vist i slutten av utskriften.:

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Analyseresultater

fra

Forekomstområde 2030 - 023 Gjeddevann

Elementanalyser

( *=parts pr. million, #=parts pr.billion, Negative verdier betyr under deteksjonsgrensen.)

Prøvenr.	Prøvetype	Au#	As*	S%	V*	Cr*	Rb*	Sr*
SP-30	Løsblokk	9630.0	8	.66	28	10
SP-33	Fastfjell	440.0	31500	.44	11	17	55.0	11.0
93/1	Fastfjell	4740.0	13	1.18	17	16
93/3	Løsblokk	1250.0		.87	13
93/4	Løsblokk	1200.0	48	.59	9	7
93/5	Løsblokk	1000.0		.08	13	11
93/6	Løsblokk	4490.0	5842	.09	26
93/6-1	Løsblokk	9100.0	15	.85	21	6

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Faktaarket ble generert 08.05.2024

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