A Regional Lithostratigraphy for Southern and Eastern Sulitjelma, North Norway
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A regional lithostratigraphy for southern and eastern Sulitjelma, north Norway ROBERT H. FINDLA Y Findlay ' R . H.: A regional lithostratigraphy for southern and eastern Sulitjelma, north Norway . Norsk . Geologtsk Ttdsskrift, Vol. 60, pp. 223-234, Oslo 1980. ISSN 0029-196X. A revised regional lithostratigraphy is described for the Sulitjelma region. T ectonic boundaries occur at two levels i� the lithostratigraphic column; these tectonic boundaries correlate with the soles of the Gasak and P1eske Nappes. R. H. Findlay, 45 Leitch St., Christchurch 2, New Zealand. Early work (Sjøgren 1896, 1900a, 1900b, Holm Sulitjelma Amphibolites sen 1917), culminating in the regional study of Greater Furulund Group - Pieske Nappe Vogt (1927) identified the major rock types and Inferior their distribution within the Sulitjelma region. SjØnstå Group The Sulitjelma area was visited briefly by Pieske Marble Kautsky (1953) who, on the basis of extensive Sparagmite-Gneiss Formation mapping in Sweden, considered the region to be Lower Mica Schist Formation formed by four superimposed thrust nappes, Basement Gneiss identifiable in Sweden as the Pieske, Salo, Vas ten and Gasak Nappes. The regional outcrop pattern (Fig. 2) is domi These and later studies (Nicholson 1966, Ma nated by large basin-and-dome structures caused son 1967, Wilson 1968, Henley 1970) were ably by interference of two sets of folding on north reviewed by Nicholson & Rutland (1969) who and northeast trends; these folds refold early revised the regional lithostratigraphy, identified recumbent folds. Sulitjelma township Iies in the the sole of the Gasak Nappe, and confirmed the core of an east-west trending antiform with the conclusions of Wilson (1968) that the sole of the basin-like Baldoiavve structure to the south; to Vasten Nappe does not occur at Sulitjelma. the north, in the cliffabove Sulitjelma township, Kollung (1970a, 1970b) and myself (Findlay a tectonised zone intervenes between an overly 1972) remapped the region to the east of the ing sequence of high grade schists (Sulitjelma Sulitjelma/Balvatnet road, and to the south of Schists) and a lower sequence of calcareous Baldoiavve and Balvatnet. This paper aims to garnetiferous hornblendic pelites (Furulund summ�rise our work, revise slightly and add Group). The tectonic contact between these two detail to the lithostratigraphy of Nicholson & formations persists eastward along the northern Rutland (1969), and to describe in the Sulitjelma side of Lomivatnet, and crops out also to the region the possible sole of the Pieske Nappe. I south of Balvatnet (Fig. 2), where it separates modify (see below) the lithostratigraphy of Ni the amphibolite facies calcareous pelites of the cholson & Rutland (1969) which formed a work Furulund Group from the overlying staurolite ing basis for field work, and describe two new amphibolite facies, aluminous and calcareous formations below th Pieske Marble. I have seen Sulitjelma Schists. neither the Fauske Marble in its type locality, In the region of Basshaugen (Fig. 2), there nor the Sulitjelma Gabbro. occur two erosional windows exposing a con Fauske Marble Group tinuous sequence from the top of the Furulund upper Group to the Basement Gneiss. These windows Sulitjelma Schists - Gasak Nappe lower are the southern 'Kragelva window' (Kragdalen 16-Geologisk Tidsskr. 4/80 224 R. H. Findlay NORSK GEOLOGISK TIDSSKRIFT 4 (1980) ° 67 � Basement Gneiss 25 km Fig. l. Locality map showing Sulitjelma and study region. inlier of Nicholson & Rutland (1969)) and the synformally folded into the Pieske Marble, the northern 'Knallerdalen window' (Fig. 3). Within Sparagmite-Gneiss Formation (new formation: the Kragelva window three formations underlie this paper), and the Lower Mica Schist Forma successively the SjØnstå Group: the Pieske Mar tion. I did not tind the base of the Lower Mica ble, the Lower Mica Schist Formation (newly Schist Formation in the Knallerdalen window. described formation) (Kollung 1970b), and a thin In the northern part of the Knallerdalen sparagmite, all of which overlie the Basement window, rocks of the Furulund Group are thrust Gneiss. However, in the Knallerdalen window locally over beds of the underlying SjØnstå the downward lithological succession below the Group, which is thinner here than to the south or SjØnstå Group is as follows: Pieske Marble, a east, and which in turn may be thrust locally gre y-green garnet-biotite-muscovite-chlorite over the Pieske Marble. schist (which I identify as Sjønstå GrouJ?) The granite and leucocratic gneisses often TASLE l Nomenclature of the major lithostratigraphic groups according to previous workers. l VOGT (1927) KAUTSKY (1953) l HENLEY (1968) NICHOLSON & THIS PAPER RUTLAND l (1969) --- � Baldoiavve Sulitjelma schist Sulitjelma Upper o. ""�'"' '""�"' o. sch1st Gasak Nappe Upper Gro up � Sulitjelma Baldoiavve sequence with r----- z + with schist Unit Schists Lower "' � Schists Ska ti Sulitjelma Sulitjelma Sulitjelma Gabbro "' """ l � (South) � sch1st Gabbro Gabbro <.9 Gabbro Junction Unit Tectonic Discontinuity Sulitjelma Amphibolite Vasten Nappe Amphibolites Sulitjelma Amphibolites -- +' •ri Furulund � � o. Furulund :> "' Lower � � z Pi eske � Furulund Group Furulund Group 3 " o "' Sulitjelma schist _, Group "' " •ri '" Schists Sjt'lnst� Muorki Sj6nst� Nappe SjØnst� Group Sjlmst� Group Gneiss Schist Gro up (West l (East l --'---- Pieske Marble l Tectonic Discontinuity NORSK GEOLOGISK TIDSSKRIFT 4 (1980) Lithostratigraphy for Sulitjelma 225 TASLE 2 : Generalised lithostratigraphy of the Sulitjelma Schists. SULITJELMA AND DUOLDAGOP BALDOIAVVE SKAI TI Garnet phyllite, calcareous- Graphite schist above Calcareous biotite pelite banded gre y semi-pelites calcareous-banded schists with development of and diopside-bearing unit. diopside, garnet and Marble, quartzites and Granites and trondhjemites. hornblende. Intermittent rust y schists quartzite. Ul "' Aluminous staurolite kyanite Aluminous schists probably Orange rusty (kyanite) .... "' Ul 0.. schists (Lap he Ueren equivalent to Laphelleren schists, interbedded H 0.. "' => schists) with Furulund schists. Granite sil l. with staurolite schists, (.) Granite and leucocratic staurolite garnet Ul gneiss bodies. schists, biotite schist .,; :>:: and gneiss bodies. ..:1 Trondhjemites low in "' >-, section. .... H ..:1 => "' "' "' arnet calc. ;:. -pelites, o ..:1 bolites, �are'"""''''' marble. Tectonic breccia and Sulitjelma Amphibolites (Junction Unit of Henley,, 1970) Pelites of the Furulund Gro up j known colloquially as 'Furulund Granite', and of the stream of Skaitibukta, beyond Tjerfjellet which occur extensively throughout the lower and towards Storfjell I (see Figs. 2 and 4). part of the Sulitjelma Schists, clearly do not form Two subdivisions are discernible in the Suli a unique lithostratigraphic marker (Fig. 2). I tjelma Schists south of Balvatnet. The lower suggest that the term 'Furulund Granite' should formation (Lower Sulitjelma Schists) is com remain restricted to that granite seen in the posed of rusty-weathering grey-purple garnet Kobbertoppen region (spot height 10 12, Fig. 2), staurolite-biotite schists, subsidiary grey phyl above the town of Sulitjelma. lites, and numerous hornblendic amphibolites, and contains also acidic volcanogenic rocks similar to the Inferior Furulund Schists de scribed later in this paper. The Lower Sulitjelma Schists form a 'wedge' which although thicken Lithostratigraphy ing eastward from Skaitibukta (Figs. 2 and 4), is cut out by the U pper Sulitjelma Schists im Sulitjelma Schists mediately to the west of Skaitibukta. South of Balvatnet the schists overlying the Although in the shore section at Skaitibukta Furulund Group are comparable to those form the contact between the Lower and Upper Suli ing the Baldoiavve Group (Vogt 1927, Henley tjelma Schists is well-exposed, the contact is lost 1970), and have been correlated also with the inland among isolated outcrops of a rusty-weath Sulitjelma Schists north of Langvatnet by Ni ering, gre y, kyanite-quartz-mica schist, a cholson & Rutland (1969) (see Tables l and 2). sheared diopside-bearing pelite, and a dark au South of Balvatnet the base of the Sulitjelma gen-gneiss, all lying within a synform within the Schists is marked by a zone, 6- 10 m thick, Upper Sulitjelma Schists (synform A:Fig. 4). consisting of a tectonic melange of Sulitjelma The lowermost rocks of the U pper Sulitjelma Schists, Sulitjelma Amphibolites, and Furulund Schists are composed of garnet-chlorite schists Group. This zone, identical to that mapped containing limestone lenses and a coarse northeast of Langvatnet as 'Junction Unit' by hornblende amphibolite overlain by rusty weath Henley in 1970 and forming the sole of the Gasak ering, grey, kyanite-quartz-mica schists. Overly Nappe (Nicholson & Rutland 1969), can be ing these schists and separated from them by an traced west from the lower northern slopes of intermittent thin, black quartzite is a calcare Jouska, through a sericite schist near the mouth ous-banded biotite-bearing dark pelite (Diopside 226 R. H. Findlay NORSK GEOLOGISK TIDSSKRIFT 4 (1980) Kobbe li 2Km. SCALE O HEIGHTS IN METRES Boldoiovve Colcoreous ond kyonite schists -� - -�./ -- 7 �-/ -....... � ....... ....... l / · l Jousko i 1273 NORSK GEOLOGISK TIDSSKRIFT 4 (1980) Lithostratigraphy for Sulitjelma 227 l i NORWAY j SWEDEN i ' ) il -,.._; - ,...; -. _/ -r.J --- .7 -- __ / r.J// -7 -r-J LEGE ND Top not seen GA SAK NAPPE Pl ESKE NAPPE PIESKE MAF:BLE :--o] SULITJELMA GABBRO � - ··: SPARAGMITE-