The Btructuie in the area of mineralization on Ulveryggen

Transcription

The Btructuie in the area of mineralization on Ulveryggen
The Btructuie in the area of mineralization on
Ulveryggen, Repparfjord, Finnmark
BY
Paul H. Reitan
With 1 text-figure
In tne Norges Geologiske Undersøkelse Årbok 1956, Vokes (1957)
published a report on some copper sulphide parageneses from the
Raipas formation of Northern Norway. This report included a dis
cussion of the disseminated mineralization in the arkosic sandstone of
I^iver^ZZen, v/liick is to be found on topographic map sheet Reppar
fjord V 3, at 70° 26' N and 13° 32' E Oslo. Since that time the writer
has made an examination ok the structure of and around the area of
known rnineraii^ation on I^ivel^ZZen as a part of a general geological
inveBtiZation of the NoltnelnrnoBt li.aipaB tectonic "win6ow". It is
therefore thought advisable to supplement and amplify Vokes' report
on the mineralization of Ulveryggen at the earliest possible time by
tne pubiication of tne rnap inclu6e6 nere, even though the investiga
tion of the entire Raipas "window" now being conducted by Norges
Geologiske Undersøkelse is not yet completed.
I^or a 6eBcription ok tne general ZeoioZ^ of tne area tke rea6er 18
rekerre6 to Holte6anl (1918), (1953), Btrand (1952) an6VolceB (1957).
Inc area >vitnin vviiicn Icnown rnineraii^ation on Hiver^ZZen
occulB 18 locate6 adout in tne center ok tne accornpan^inZ rnap. It 18
louM> eliptical in Bnape; adout 1700 rneterB lonZ an6400 rneterB
broa6. >Vitnin tniB area are
ok low-Zra6e rnineraii^ation >vnicn
are Beparate6 d^ darren or virtuaii^ darren Ban6Btone.
area Bnown on tne niap i8a6jacent to a niZn anZie kauit nnicn
drinZß tne arl(oßic Ban6Btone into contact xvitn Zreenßtoneß an6Zreen
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sckißtß. Inc kauit 6ipß at adout 90 6eZreeß to tne 80utnea8t. (^,ll anZleß
are daße6 on 400 6eZree cornpaßß.)
tne kauit 18 a ?one ok pn^iionite.
tne aZe reiation detxveen tne Ban6Btone an6Zreenßtoneß 18
not >et certain it i8tentativei^ tnouZnt tnat tne Zreenßtoneß are oicier
(Bee Btran6, 1952). Inuß tne kauit 18 prodadi^ a reverße kauit.
The arkosic sandstone in the vicinity of the area of known mineral
ization occurs as an elongate dome about 9 km by 3 km, parallel to
tniB fault. The area of known mineralization lies on the southeast flank
of this dome. Throughout the major part of the dome tne BtructureB
are quite regular, i. e., there are no sharp NexureB, ko!68 or
significant faults. In this respect the area of known mineralization
is exceptional.
Besides tne faults which are shown on the map there can be seen
many small zones of faulting and/or shearing; but such that there is
no marked change in lithology or dip and strike on croBBinZ tneBe
zones. These zones are usually marked by rninor, elonZate topoZrapnic 6epreBBionB.
I^oiiowinZ kor tne rnoBt part a!rnoBt alonZ tne BoutneaBt Bi6e ok tne
area ok rnineraii^ation tnere can de Been a Brnall anticiine. Inc axiB ok
tne anticiine Btril(eB adout f>s 55 k^, an6adout oppoBite tne rni66le ok
tne rnineraiixeck
tne plunZe ok tne anticiine cnanZeB Buen tnat to
tne nortneaBt tne plunge i8adout 40 8W v/kile to tne Boutn>veBt tne
plunZe i8adout 20 I^L.
lo tne BoutneaBt tne area ot rnineraiixation 18 approxirnatei^
doun6e6 d^ tne creBt ok tne anticiine an6to tne nortnweBt d> tne kauit
runninZ detween an6v^' on tne rnap.
lne arnount ok 6iBplacement alonZ tne kaultB Bno>vn on tne rnap i8
un6eterrnine6. Been in 6etail tnere are quite conBi6erad!e variationB in
tne Zrain Bi?e an6tne BortinZ ok tne Ban6Btone, dut tneBe variationB are
80 Birnilar tnrouZnout tnat it 18 at deBt extrerne!> ciikncuit to nn6 rnarlcer
de6B d^ wnicn tne arnount ok 6iBplacernent can de 6eterrnine6. Now
ever, tne writer >vou!6 «o^ wiBn to ruie out ttie poBBidilit> tnat d)s ver>
carekui inveBtiZation ot tne area an6tnorouZn karniiiarit^ >vitn tne
litnoioZical variationB ok tne Ban6Btone a cornpetent ZeoloBiBt cou!6
BucceBBkull>" rnalce tkeBe 6eterrninationB.
v^n a66itional Bupplernentar^ cornrnent to Vo^eß' (1957) report,
daße6 on odßervationß ok 6iarnon6 ckriii coreß wiiicn Invex (korpora
tion, Toronto, (^ana6a, Icin6l> allo>ve6 tne writer to Bee, i8tnat p^rite
i 8preBent in tne I^iver^ZZen rnineraiixation. 11ii8 rninerai waß not
79
preBent in tne Barnpleß Plovi6e6 Vokeß dv pa^^et,
INVBelk.
an6
LecauBe tne accompanvinZ rnap 18 daBe6 on aerial pnotoZrapNB
tnere 18 a certain Brnall arnount ot 6iBtortion tnrougnout it.
Sammendrag
Strukturer i det mineraliserte område på Ulveryggen,
Repparfjord, Finnmark.
I forbindelse med N. G. U.'s generelle geologiske kartlegging av
det nordligste Raipas- «vinduet» har forfatteren laget et strukturelt
kart over det mineraliserte området pa Ulveryggen ved Repparfjord,
70° 26' N og 13° 32' 0 Oslo, på kartblad Repparfjord V 3. Trass i at
undersøkelsen av hele «vinduet» ennu ikke er ferdig er kartet nu
publisert for å utfylle Vokes' (1957) avhandling som gjaldt, blandt
annet, mineralisering i Ulveryggen-forekomsten.
Det mineraliserte området ligger like ved en hovedforkastning
mellom den arkosiske sandstein på Ulveryggen og grønnsteinen mot
syd-øst. Området er også tydelig mere strukturelt forstyrret enn sand
steinen ellers, med en liten antiklinal langs syd-østsiden av forekomsten
og en forkastning langs nord-vestsiden, som sees på kartet mellom
A og A'. I området fins også mange soner med tydelige skjærbevegelser.
?a Zrunn av mangel pa le6enoriBonter die ikke BtsrreiBen pa kor
kaBtninZene avkort.
Bo!Nlneren 1957 iakttok korkatteren BvovelkiB i dorkjernene kra
I^sivervZZen, Born Invex (Corporation, Toronto, d!ana6a, var 8a venn
liZ a Btille til K. (5. I^.'B 6iBpoBiBjon. vette rninerai var ikke tiiBte<se i
provene Born ?a6Zet, Ivlc<l!an6leBB oZ jeZ Barnlet kor VokeB.
Literature
Holtedahl, Olaf, 1918, Bidrag til Finmarkens geologi: Norges Geol. Undersøkelse, Nr. 84.
— 1953, Norges geologi: Norges Geol. Undersøkelse, Nr. 164.
Strand, Trygve, 1952, Raipas og kaledon i strøket omkring Repparfjord, Vest-Finnmark :
Norges Geol. Undersøkelse, Nr. 183, Årbok 1951, pp. 22—31.
Vokes, F. M., 1957, Some copper sulphide parageneses from the Raipas formation of
Northern Norway: Norges Geol. Undersøkelse, Nr. 200, Årbok 1956, pp. —111.