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THE ORE DATABASE
Occurence 1813 - 021 Kråa
(Object Id: 2937)
(Last updated: 15.05.2006)

Location
County: Nordland Municipality: Brønnøy (1813)
Map 1:50000: Velfjord (1825-4) Map 1:250000: Mosjøen
Coordinate system: EU89-UTM Zone 33
East: 385122 m. North: 7247598 m.
Longitude: 12.5328530 Latitude: 65.3310550
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Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Zinc
Element(s): Zn Cu Kis
Importance
Raw material meaning: Little Importance (reg. 18.02.2015)

Resources and production
Activity: Exploration Reserves:
Operating method: Historical production:


Operations
From - To Activity Comments
1982 - 1983 Geochemistry Company/Institution :BP Norge A/S Minerals
1983 - 1983 Geochemistry Company/Institution :BP Norge A/S Minerals
1994 - 1994 Sampling Company/Institution :NGU-malmreg.

Mineralization
Era: Paleozoic Period: Ordovician
Genesis: Replacement/Metasomatism Form: Lens
Main texture: Structureless Min. distribution: Semi-massive (20-50 % ore minerals)
Main grain size: Medium grained (1-3 mm) Main alteration: Skarn formation
Strike/Dip: 16 / 90 Direction:
Plunge:
Stratigraphic classification of host rock
Era: Paleozoic Period: Ordovician
Province: Caledonides
Geotec.unit: Helgeland Nappe Complex
Tectonic complex:
Igneous complex: Bindal Batholith
Group: Formation:

Mineralogy
Relationship Mineral Amount
Gangue mineral Pyroxene Major mineral (>10%)
Gangue mineral Feldspar Subordinate mineral (1-10%)
Gangue mineral Hornblende Subordinate mineral (1-10%)
Ore mineral Pyrrhotite Major mineral (>10%)
Ore mineral Sphalerite Major mineral (>10%)
Ore mineral Pyrite Subordinate mineral (1-10%)
Ore mineral Chalcopyrite Subordinate mineral (1-10%)

Lithology:
Relationship Rock Origin
Host rock Kalksilikatgneis Sedimentary
Metamorphic facies :Contact
Wall rock Monzodioritt Intrusive
Original rock :Monzodiorite
Wall rock Marmor Sedimentary
Original rock :Limestone
Metamorphic facies :Contact

Structures
Location: Type: Orientation(360 gr.): Relation to min.:
Host rock Mineral banding Strike/Dip :7 / 15 Pre-mineralisation ;...Effect :None
Host rock Joints/Fractures Strike/Dip :16 / 90 Syn-mineralisation ;...Effect :Controls

Information(s) in free text format
Free text
Forekomsten ble påvist av BP Norge A/S Minerals i forbindelse med oppfølging av bekkesedimentanomalier under gullprospektering i Helgeland 1981-84. Den opptrer innenfor en av de mange inneslutninger av marmor og båndete kalksilikatgneiser i Sausfjellet monzodiorittpluton. Mineralisering finnes over en lengde av 50 m i skjæringene langs tømmerveien mellom Hongset og Sørlia ved Fuglevatn og 50 m SV for plassen Kråa. Langs veien og Kråelva like i SV opptrer finbåndete (1-10 mm) grønnlige kalksilikatgneiser med små kropper og ganger av middels- til grovkornet monzodioritt. Kalksilikatgneisene fører 0,2-1 m brede og ca. N-S strykende soner med magnetkis-, litt kobberkis- og svovelkis-disseminasjon. Sonene opptrer ofte langs kontakten av monzodioritt som også inneholder disseminerte sulfider. Den rikeste mineraliseringen utgjøres av en 0,8 m bred og massiv sinkblendesone/linse (strøk/fall: 16/90) omgitt av sterk magnetkisdisseminasjon i middelskornet grønn klinopyroksen (diopsid) skarn. Kalksilikatgneisene/klinopyroksenskarnet gjennomsettes av opptil 3 cm brede kvarts- og kvarts-kalkspatårer med svart hornblenderand. Langs elven finnes også disseminert magnetkis i gneisene som gjennomsettes av granitt-pegmatittårer med små magnetkis- og svovelkis-aggregater.

Bibliography:
From NGU's Reference Archive:
Myrland, Rolf , 1972
Velfjord. Beskrivelse til det berggrunnsgeologiske gradteigskart I 18 - 1:100 000.
;Norges geologiske undersøkelse;KARTBESKRIVELSE; TIDSSKRIFTARTIKKEL;NGU; Skrifter; No.274; 1;1-30 + ka pages
Abstract:
The various lithologies are described. These comprise granitic basements rocks of supposed Pre-Cambrian age and Cambro-Silurian supracrustals and intrusives. The intrusives are mostly found within the Bindal and Velfjord massifs. These massifs are younger than the supracrustals, but their mutual age relationship is uncertain. Tectonically the rocks are sitated in "the high metamorphic nappe-complex" of central and western Helgeland. The supracrustal rocks have undergone at least three phases of Caledonian folding, the F2 phase producing the main regional structures. The rocks have mineral assemblages which place them in the almandine-amphibolite metamorphic facies.

Barnes, Calvin G.; Prestvik, Tore; Nordgulen, Øystein; Barnes, Melanie A. , 1992
Geology of three dioritic plutons in Velfjord, Nordland.
;Norges geologiske undersøkelse;TIDSSKRIFTARTIKKEL;NGU Bulletin; No.423;41-54 pages
Abstract:
Dioritic plutons in the Velfjord area of Nordland intrude calc-silicates and migmatitic pelites of the Helgeland Nappe Complex (HNC). The three largest plutons were emplaced in a zone of NNW-SSE regional strike rather than the more typical NE-SW strike. The plutons postdate Caledonian F2 structures; however, anatectic granites increase in abundance toward the plutons, which suggests emplacement and subsequent partial melting of the pelitic host rocks soon after peak metamorphism. The dioritic and granitic bodies were deformed with interstitial melt present; deformation continued during cooling to greenschist facies conditions. Structural position, style and timing of deformation, and assymetric zoning of the plutons are consistent with intrusion into a dilatant part of a regional sinistral shear zone.

Fieldsamples
Sample No. Sample type Miscellanrous
NO0835.01 Bedrock
Sampler: Ihlen, P.M./...Stored: Løkken
Comment: Semi-massiv grovk. sl-malm med litt po.
No. of registrated element analyses = 1
NO0835.02 Bedrock
Sampler: Ihlen, P.M./...Stored: Løkken
Comment: Middk. rik po-diss. og et par py- og sl-slirer i grønn pyroksenskarn med diorittiske rester (hbl. + plag.).
No. of registrated element analyses = 1
NO0835.03 Bedrock
Sampler: Ihlen, P.M./...Stored: Løkken
Comment: Svak po-diss. i nebulittisk monzodioritt.
No. of registrated element analyses = 1
NO0835.04 Bedrock
Sampler: Ihlen, P.M./...Stored: Løkken
Comment: Rik po-diss i fink. grønn pyroksenskarn med et par py-belagte sprekker.
No. of registrated element analyses = 1
NO0835.05 Bedrock
Sampler: Ihlen, P.M./...Stored: Løkken
Comment: Grønn middk. skarn med monzodiorittiske rester. Svak po-diss.
No. of registrated element analyses = 1
NO0835.06 Bedrock
Sampler: Ihlen, P.M./...Stored: Løkken
Comment: Grønn middk. skarn med moderat til svak diss av po. Gjennomsatt av pegmatittårer med po- og py-aggregater (elva).
No. of registrated element analyses = 1
NB! All analyse values are shown at the end of the printout.:

Name of Locality: Kråelva
(Object Id: 3783 21,01,00)

Location
County: Nordland Municipality: Brønnøy (1813)
Map 1:50000: Velfjord (1825-4) Map 1:250000: Mosjøen
Coordinate system: EU89-UTM Zone 33
East: 385082 m. North: 7247608 m.
Longitude: 12.5319860 Latitude: 65.3311300
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Resource
Resource Type: Base metals (Cu,Zn,Pb,Fe sulphides, As,Sb,Bi,Sn) Resource Subtype: Zinc
Element(s): Zn Cu Kis
Resources and production
Activity: Exploration Reserves:
Operating method: Historical production:



Analyse Results
from
Deposit Area 1813 - 021 Kråa

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#
NO0835.01 Bedrock 522 99999 42 36 19 -.3 10.0
NO0835.02 Bedrock 1717 9435 8 348 101 1.2 18.0
NO0835.03 Bedrock 57 27 3 31 47 -.3 12.0
NO0835.04 Bedrock 1094 937 40 58 63 1.0 11.0
NO0835.05 Bedrock 309 86 4 40 59 .4 9.0
NO0835.06 Bedrock 279 19 -3 32 25 .6 14.0
------------------
Sample No. Pt# Pd# Rh# As* Cd* Ba* Mo* Sb* Bi*
NO0835.01 -3.0 3.0 -5.0 35 263.1 10 2.00 -2 4
NO0835.02 -3.0 -3.0 -5.0 8 18.7 5 -1.00 -2 9
NO0835.03 -3.0 -3.0 -5.0 -2 -.2 23 -1.00 -2 2
NO0835.04 -3.0 -3.0 -5.0 5 1.7 3 -1.00 -2 -2
NO0835.05 -3.0 -3.0 -5.0 4 -.2 2 -1.00 -2 -2
NO0835.06 -3.0 3.0 -5.0 2 -.2 3 1.00 -2 -2
------------------
Sample No. S% V* Cr* Mn* Fe% Th* U* W* Sr*
NO0835.01 11.62 14 7 357 6.21 2.00 -5.00 15 72.0
NO0835.02 16.74 8 10 70 26.59 2.00 -5.00 -2 28.0
NO0835.03 1.39 22 15 124 3.37 -2.00 -5.00 -2 29.0
NO0835.04 8.63 24 6 156 15.72 -2.00 -5.00 -2 33.0
NO0835.05 4.09 20 7 125 6.51 2.00 8.00 -2 21.0
NO0835.06 6.73 4 -1 116 10.81 4.00 5.00 -2 13.0
------------------
Sample No. La* B*
NO0835.01 15.00 -3
NO0835.02 9.00 5
NO0835.03 6.00 4
NO0835.04 18.00 -3
NO0835.05 16.00 4
NO0835.06 10.00 -3


The fact sheet was created on 29.03.2024

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