NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 209

New insights into the geology of high-grade Caledonian marbles based on isotope chemostratigraphy

Victor A. Melezhik, Bouke K. Zwaan, Gedeminas Motuza, David Roberts, Arne Solli, Anthony E. Fallick, Igor M. Gorokhov & Anton B. Kusnetzov

Melezhik, V.A., Zwaan, B.K, Motuza, G., Roberts, D., Solli, A., Fallick, A.E., Gorokhov, I.M. & Kusnetzov, A.B. 2003: New insights into the geology of high-grade Caledonian marbles based on isotope chemostratigraphy. Norwegian Journal of Geology,Vol. 83, pp. 209-242. Trondheim 2003. ISSN 029-196X.

A first attempt to employ carbon and strontium isotope stratigraphy together with 1.20,000 scale mapping for chronstratigraphic subdivision and geological correlation of non-fossiliferous sedimentary successions in the polydeformed, high-grade, marble-dominated terrane has been success- δ13 δ18 87 86 ful. The isotope stratigraphy was based on 315 analyses of major and trace elements, as well as on 231 Ccarb and O, and 104 Sr/ Sr whole- rock analyses of calcite and dolomite marbles, representing all major marble units of the Narvik, Evenes and Niingen nappe complexes, and the Bogen Group in the north-central Norwegian Caledonides. A thick succession of calcite and dolomite marbles in the Ofoten Synform, previously considered to be stratigraphically homogeneous and of Late Ordovician-Early Silurian age, is shown to be a complex assemblage of Neoproterozoic, Cambrian and Early Silurian carbonate formations which were tectonically imbricated and emplaced in a non-chronostratigraphic order. The real breakthrough with the new geological mapping has been the establishment and use of the Cambrian and Early Silurian chemo/chronostratigraphic markers that reveal stratigraphic heterogeneity and tectonic repetition, provide a reliable stratigraphic subdivision, and facilitate the compilation of a chronologically-based geological map.

Melezhik, V.A., Zwaan, B.K, Roberts, D. & Solli, A., Norges geologiske undersøkelse, 7491 Trondheim, Norway; Motuza, G., University of Vilnius, Chi- urlionio 21, Vilnius, Lithuania; Fallick, A.E., Scottish Universities Environmental Research Centre, G75 0QF East Kilbride, Glasgow, Scotland; Gorok- hov, I.M. & Kusnetzov, A.B., Institute of Precambrian Geology and Geochronology, nab. Makarova, 2, 199034 St. Petersburg, Russia

Introduction leading to the formation of carbonate deposits of diffe- rent kinds. The Ofotenfjord area (Fig. 1) has been cho- Despite abundant petrological and structural studies, sen as a first-priority target because of the presence as well as geological mapping, performed over several there of a vast volume of marbles constituting part of decades in the North-Central Norwegian Caledonides the Uppermost Allochthon in that region. The main by both Norwegian and international research teams objectives of this contribution are (i) to illustrate the (Foslie 1946, 1949; Gustavson 1966, 1972, 1974a, use of isotope stratigraphy for indirect dating, subdivi- 1974b; Bartley 1981; Boyd 1983; Boyd & Søvegjarto sion and correlation of high-grade marble sequences; 1983; Boyd et al. 1986; Tull et al. 1985; Steltenpohl and (ii) to demonstrate progress towards the produc- 1987; Steltenpohl & Bartley 1987; Steltenpohl et al. tion of a new generation of geological maps in high- 1990; Tucker et al. 1990; Oliver & Krogh 1995; Andre- grade metamorphic terranes, as based on detailed map- sen & Steltenpohl 1994; Coker et al. 1995; Northrup ping combined with strontium and carbon isotope 1997), little research and detailed geological mapping stratigraphy. has been done on marble formations in the Norwegian Caledonides. At the Geological Survey of Norway, a special project entitled ‘Carbonate formations of Nor- Analytical techniques way: from basic research to industry’ has been launched to study depositional environments, metamorphism, Analytical techniques are described in Appendix 1. stratigraphic correlation and ages of marble formations in selected regions of the Norwegian Caledonides. With the main goal of the project being to develop an explo- Regional geology, metamorphism, ration strategy for new marble deposits, a significant amount of basic research has been required in order to deformation and isotopic ages establish a reliable tectonostratigraphic base that aims The study area is located north of Ofotfjorden and Her- at discriminating between the local and regional factors jangsfjorden and south of Astafjorden (Figs. 1 & 2) and 210 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

In the area north of Ofotfjorden, lithologies within the Narvik nappe complex include garnet-mica schists, cal- careous schists, monotonous biotite schists and subor- dinate bituminous schists, amphibolites, keratophyres, and marbles metamorphosed at amphibolite-facies. The Narvik nappe complex is separated from the over- lying Evenes nappe complex by a thin tectonic unit of amphibolites and tonalites. Similar rocks on the sout- hern side of Ofotfjorden were described by Boyd (1983) as representing an ophiolite fragment (Fig. 3), which together with the overlying Elvenes Conglomerate was termed the Bjerkvik Nappe. The latter is separated from both the Narvik and the Evenes nappe complexes by tectonic contacts (Melezhik et al. 2002a).

The next tectonostratigraphic unit is the Evenes nappe complex, composed of several discrete units of different age which were tectonically emplaced in a non-strati- graphic order (Melezhik et al. 2002a). In ascending structural order, these are the Steinsland, Ramstad, Eve- nestangen and Tangen thrust sheets (Fig. 3). Also inclu- ded are the Langmark schists (Fig. 3) whose relative and absolute age and contact relationships with adja- cent units remain unknown. The Langmark schists could belong to either the Steinsland or the Ramstad thrust sheets (Figs. 2 & 3). The Steinsland, Ramstad and Evenestangen thrust sheets and the Langmark schists, collectively, correspond to the Evenes Marble of Gus- tavson (1966) and Steltenpohl et al. (1990). Fig. 1. Location of the study area and simplified tectonic subdivision of the Scandinavian Caledonides (modified after Roberts & Gee 1985). The contact of the Evenes nappe complex with the structurally overlying Bogen Group has been defined as represents the northeastern extension of the Ofoten a thrust (the Bogen thrust of Andresen & Steltenpohl Synform. The investigated area exceeds 800 km2,of 1994). However, the precise tectonostratigraphic posi- which 150 km2 has been covered by : 20.000 scale geo- tion of the thrust remains unclear. Originally, it was logical mapping undertaken between 1997 and 2000. placed structurally above the marble of the Tangen The bedrock geology is dominated by two principal Sequence (Steltenpohl & Bartley 1985; Steltenpohl subdivisions; parautochthonous Precambrian crystal- 1987). Later, the Tangen Sequence was extended up to line basement and overlying, allochthonous, Caledo- the base of the Bø Quartzite (Fig. 3) and the thrust was nian nappe complexes (Gustavson 1974a, b; Bartley placed at the structural base of this quartzite unit (Stel- 1981; Tull et al. 1985; Steltenpohl 1987). The allochtho- tenpohl et al. 1990; Andresen & Steltenpohl 1994). The nous complexes include the lowermost unit of quartz- detailed mapping performed by the present authors has feltspatic gneisses and granitic gneisses, and the Narvik, failed to confirm the presence of a major thrust at the Evenes, Bogen and Niingen Groups (Fig. 2, see page structural base of the Bø Quartzite. Instead, a thrust 213). The Narvik and Niingen Groups have previously and associated retrograde metamorphism have been been redefined as the Narvik and Niingen nappe com- documented structurally above the Tangen Sequence plexes (Andresen & Steltenpohl 1994). Similarly, the marble. Thus, we prefer the position of the thrust as it Evenes Group is re-defined as the Evenes nappe com- was originally defined by Steltenpohl & Bartley (1985) plex for reasons explained in Melezhik et al. (2002a) and Steltenpohl (1987). The current lithostratigraphy and later in this paper. In terms of the principal subdi- of the Bogen Group includes a variety of amphibolite- visions of the Scandinavian Caledonides (Roberts & facies mica schists (Lower, Middle and Upper Mica Gee 1985), the Evenes, Bogen, and Niingen units are Schists, Fig. 3), quartzites, iron-manganese ores and considered to form part of the Uppermost Allochthon, several marble formations (Foslie 1946; Gustavson with the Narvik nappe complex representing the Upper 1966; Steltenpohl 1987; Steltenpohl et al. 1990). Abun- Allochthon (Fig. 2). In the area of Ofotfjorden, the dant felsic dykes in the Bogen Group schists and mar- lowest structural unit of the Caledonian nappe pile is bles contrast strongly with the subjacent Evenes nappe the Middle Allochthon (Fig. 2) which does not concern complex, which lacks such intrusions (Steltenpohl us here. 1987; Steltenpohl & Bartley 1987). NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 211

Fig. 3. Tectonostratigraphic column of the Uppermost Allochthon in the Ofoten district (based on Gustavson 1966, 1972; Boyd et al. 1986; Stel- tenpohl et al. 1990; Andresen & Steltenpohl 1994; Melezhik et al. 2002). The ages of the carbonate formations are based on δ13C and 87Sr/86Sr values of carbonates with reference to the age calibration curves of δ13C and 87Sr/86Sr in seawater (this study). The age of the ophiolite fragment (Boyd 1983) structurally beneath the Elvenes Conglomerate is constrained by the U-Pb age (469 ± 5 Ma) of a metatonalite from the correlative Lyngen Ophiolite Complex (Oliver & Krogh 1995). *Based on Andresen & Steltenpohl (1994). **Thrust or extensional fault suggested to recon- cile the large age differences between adjacent formations (see also Melezhik et al. 2002a for further explanation).

The uppermost structural unit is the Niingen nappe includes migmatitic schists and gneisses with ultrama- complex. Separated from the Bogen Group by a promi- fic inclusions, metamorphosed at kyanite grade. The nent thrust (Steltenpohl & Bartley 1987; Karlsen 1988a; metasedimentary rocks are cut by numerous veins and Andresen & Steltenpohl 1994), this nappe complex dykes of felsic igneous rocks., 212 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

All of the geological formations in the Ofotfjorden region have been affected by Caledonian, polyphase, orogenic deformation (Gustavson 1972; Tull et al. 1985; Steltenpohl 1987) with peak temperatures in the Evenes nappe complex and the Bogen Group in the order of 540°C (e.g. Steltenpohl & Bartley 1984). The emplace- ment of both the pre-kinematic Råna massif (Fig. 2) and felsic dykes in the Narvik nappe complex, was con- strained at 437 ± 1 Ma (U-Pb zircon, Tucker et al. 1990; Northrup 1997). The age of the peak metamorphism, and inferred nappe assembly, in the underlying Narvik nappe complex was reported to be c. 432 Ma (U-Pb on monazite and zircon, Northrup 1997); i.e., this occur- red during the Scandian orogeny. The ophiolite frag- ments of the Bjerkvik Nappe have been correlated with the Lyngen Magmatic Complex (Andressen & Stelten- pohl 1994), a metatonalite from which has been dated to 469 ± 5 Ma (U-Pb on zircon, Oliver & Krogh 1995). The cooling history for the entire Ofotforden region has been constrained by 40Ar/39Ar ages on hornblende (500°C) and muscovite (350°C) to 425-394 and 400- 373 Ma, respectively (Coker et al. 1995).

The Ofoten Synform is a major, late-Scandian structure Fig. 4. Isotopic and chemical variations through the lithological in the study area (Fig. 2) and farther to the northeast column of the Steinsland thrust sheet marble along the coastal sec- (Gustavson 1972; Steltenpohl 1987). This NE-SW-tren- tion at Tjeldsundbrua-Evenskjer (do not represent the entire data- ding synform plunges mainly to the northeast in the base of the Steinsland thrust sheet shown in Appendences 2 & 3). Ofotfjorden district, and deforms the regional schisto- sity, all lithostratigraphic units and thrust contacts in well as the Bogen Group, remain unknown. In the area the region. The synform is characterised by an asym- south of Ofotfjorden, approximate depositional ages of metry which is reflected in considerable changes in several marble formations of the Evenes nappe complex thickness of the Narvik and Evenes nappe complexes. and the Bogen Group have been constrained by means The structural thickness of the Narvik nappe complex of carbon and strontium isotope chemostratigraphy gradually decreases from >8 km in the eastern limb (Melezhik et al. 2002a). The least altered 87Sr/86Sr and south of Ofotfjorden, to 2 km in the western limb, thin- δ13C values of the lowermost and the uppermost mar- ning further to 0.5 km along the western limb north of ble formations of the Evenes nappe complex (i.e., For- Ofotfjorden (Fig. 2). The Evenes nappe complex shows mation I and the Tangen Sequence,Melezhik et al. the opposite asymmetry; its visible structural thickness 2002a) are consistent with Late Neoproterozoic (Ven- gradually decreases from >12 km in the western limb dian) ages, 650-600 and 620-610 Ma, respectively (Figs. north of Ofotfjorden to 3 km south of Ofotfjorden, 2 & 3); and the apparent ages of deposition of two thinning down to 1.5 km along the eastern limb and other marble formations (Formations II and III) have becoming highly attenuated on the northern side of been assigned to the Cambrian and Early Silurian. In Ofotfjorden, north of Bjerkvik (Fig. 2). the Bogen Group, the isotopic signatures of two marble units are consistent with the composition of seawater at These differential changes in structural thickness were, 700-600 Ma (Melezhik et al. 2002b). in our opinion, largely caused by a tectonic thinning that pre-dated the formation of the Ofoten Synform. In view of the overall severity of the polyphase deformation and metamorphism, it is virtually impossible to assess the Lithological features and geochemistry character of any original, syn-depositional, lithological thickness variations. This is in broad agreement with our of the main marble units earlier studies (Roberts et al. 2002; Melezhik et al. 2002a) Narvik nappe complex showing that the complex tectonic imbrication of the Evenes nappe complex is likely to have resulted from Within the uppermost part of the Narvik nappe com- both Taconian and Scandian orogenic deformation. plex in the western limb of the Ofoten Synform, a single marble unit, up to 50 m thick, is discontinuously Precise depositional ages of the schist and marble units developed from Sørtuva in the north to the Ofotfjorden of the Narvik, Evenes and Niingen nappe complexes, as coast in the south. This is a highly deformed, rather NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 213 Fig. 2. Geological map of the Ofotfjorden area (modified after Gustavson 1974; Boyd & Søvegjarto 1983; Boyd et al. 1986; Steltenpohl et al. 1990; Melezhik et al. 2002) with emphasis on the carbonate formations studied in this paper. 214 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

a e

b f

c g

d h

Fig. 5. Lithological features of some carbonate formations in the area north of Ofotfjorden. (a) – Dark grey, thinly banded, calcite marbles of the Steinsland thrust sheet. The white, pale grey and medium grey banding reflects recrystallisation. The marble shows a compositional layering deriving from the combined effects of metamorphism and tectonic thinning. The scale-bar is 9 cm. (b) – White calcite marbles of the Ramstad thrust sheet at Fjelldalsheia in the western limb of the Ofoten Synform. Note that the marble has a massive appearance. The red backpack is 40 cm in height. (c) – The Ramstad calcite marbles on the northern shore of Ofotfjorden in the western limb of the Ofoten Synform. Note the platy, mylonitic appearance of the marbles. The length of the hammer is 45 cm. (d) – The Ramstad calcite marbles in the eastern limb of the Ofoten Synform on the shore of Herjangsfjorden, west of Bjerkvik. The pale grey banding reflects recrystallisation. The white bands were those most affected by recrystallisation, causing partial dolomitisation. (e) – Dark grey, calcite marble of the Evenestangen thrust sheet in the western limb of the Ofoten Synform at Evenestangen. Note that the marbles here preserve relict sedimentary bedding. Thin, pale grey bands and lenses reflect recrystallisation and intensive dolomitisation. The scale-bar is 9 cm. (f) – Variegated calcite marble (Leivset type) of the Evenestangen thrust sheet in the western limb of the Ofoten Synform at Evenestangen. The very prominent, bright orange-pink colour, a unique isotopic composition (δ13C = -7 to -11‰) and wide lateral distribution in the North-Central Norwegian Caledonides make this particular marble a very distinctive marker (Melezhik et al. 1999). The hammer is 45 cm in length. (g) – Pale grey, banded, partially dolomitised, calcite marble of the Evene- stangen thrust sheet in the western limb of the Ofoten Synform at Evenestangen. Although the banding is reminiscent of primary bedding, it is really a compositional layering deriving from the combined effects of metamorphism and tectonic thinning. The pen for scale is 14 cm in length. (h) – Dark grey, thinly banded, calcite marble of the Tangen Sequence in the eastern limb of the Ofoten Synform, west of Bjerkvik. Note that tec- tonic deformation has obliterated all traces of primary sedimentological features and resulted in the development of the thin compositional ban- ding. The scale-bar is 9 cm. NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 215 impure, dark grey, calcite marble hosted by mica schists, The Ramstad thrust sheet – The term Ramstad thrust amphibolites and sulphidic schists. Although this marble sheet is here introduced informally to describe a dis- has been assigned to the Narvik nappe complex, it may tinctive tectonostratigarphic unit of white and pale represent the basal marble of the Evenes nappe complex grey,crystalline calcite and dolomite marbles. In the (Formation I in the area south of Ofotfjorden, Melezhik western limb of the Ofoten Synform, east of Soltun, the at al. 2002a) thrust or infolded into rocks of the Narvik Ramstad thrust sheet is located structurally above the nappe complex. At present, neither of the tectonostrati- Steinsland thrust sheet but is separated from the latter graphic alternatives can be discounted. Two samples col- by a thin unit of Langmark schist (Fig. 2). Along the lected from separate marble localities show similar δ13C profile between Fjelldalsheia and Sørtuva, where the (+5.8 to +6.0‰), δ18O (21.5 to 23.6‰) (Appendix 2) Ramstad marbles have a visible thickness of 200 m, they and 87Sr/86Sr ratios (0.70729 – 0.70735), and a Sr con- lie structurally above dark grey and variegated marbles tent ranging from 1622 to 1916 ppm (Appendix 3). of the Evenestangen thrust sheet (Fig. 6). The actual contact surfaces of the Ramstad marbles with rocks of adjacent tectonostratigraphic units has nowhere been Evenes nappe complex observed. Marble formations are present in four of the five tecto- nostratigraphic units that constitute the Evenes nappe The marbles of the Ramstad thrust sheet are represen- complex (Figs. 2 & 3). ted by three main lithological varieties: • variety 1 - white and pale grey, massive, coarsely The Steinsland thrust sheet – The term Steinsland thrust crystalline calcite marbles (Fig. 5b); sheet is here introduced informally to describe a dis- • variety 2 - pale grey, thinly banded or platy, calcite tinctive tectonostratigraphic unit of banded, crystal- marbles (Fig. 5c); line, calcite marbles. In the western limb of the Ofoten • variety 3 - pale grey, commonly massive, fine-grai- Synform, the thrust sheet is developed south and east of ned, dolomite marbles (not illustrated here). Tjeldsundbrua, where it forms a major part of the Evenes nappe complex. The marbles are overthrust by The massive marbles (variety 1) dominate over other Bogen Group schists (Fig. 2) although their contact varieties and form prominent lenses, up to 200 m thick, relationships with rocks farther south at Evenskjer are of limited lateral extent (i.e. at Fjelldalsheia, Fig. 2). ambiguous. The marbles are strongly deformed in a These marbles are characterised by an unusual ‘flame’ series of subhorizontal, tight folds. The folds plunge structure manifested in an irregular distribution of gently southeast beneath younger rock units, and there- grey and dark grey fragments (0.5 – 1.5 cm in size) with fore cannot be traced farther south towards Ofotfjor- diffuse boundaries in the white groundmass. The mas- den. Instead, the Steinsland marbles reappear in the sive appearance and form of occurrence of these parti- Glefjellet area where they are deformed in a series of cular marbles is reminiscent of reefal build-ups. The northeast-plunging folds. dolomite marbles (variety 3) occur as lenses with limi- ted strike lengths and are scattered irregularly throug- The best-exposed section is located on the coast at hout the Ramstad thrust sheet. Steinsland between Tjeldsundbrua and Evenskjer. This section has been sampled in detail for isotopic study Thirty-five samples collected from various localities in (Fig. 4). The marble unit has a grey to dark grey, ban- the western limb of the Ofoten Synform suggest that ded appearance due to a compositional layering arising the different calcite marbles within the Ramstad thrust from the effects of metamorphism and tectonic thin- sheet have similar geochemical characteristics. The ning (Fig. 5a). The marbles contain several thin layers marbles are characterised by Sr concentrations ranging of sulphide-rich graphite schist containing up to 5 wt from 66 to 515 ppm, with one outstanding outlier % of total organic carbon (TOC) (Fig. 4). Thin, sub- (3030 ppm, Appendix 2). Both the thinly banded and concordant amphibolite bodies are scattered throug- the massive, coarsely crystalline varieties have very uni- δ13 δ18 hout the marble unit (Fig. 4), and boudins of amphibo- form C values (–1.0 to +1.7‰). O shows a larger lite are abundant. fluctuation and ranges between 18.0 and 24.8‰. 87Sr/86Sr ratios fall between 0.70920 and 0.70969 δ13 Thirty marble samples, collected from various locali- (Appendix 3). At Fjelldalsheia, C values erratically ties, have Sr contents in the range 591 – 3180 ppm, decrease by 2‰ from the structural base towards the positive δ13C (+1.8 to +7.0‰) and variable δ18O (16.8 structural top of the sequence. This decrease is not to 29.0‰) values (Appendix 2) coupled with 87Sr/86Sr accompanied by systematic variations in Mg/Ca or ratios falling between 0.70677 and 0.70756 (Appendix Mn/Sr ratios (Fig. 6) and it may therefore have a strati- 3). The Tjeldsundbrua-Evenskjer coastal section does graphic significance. not show any systematic variations in isotopic and ele- mental ratios (Fig. 4). In the eastern limb of the Ofoten Synform, the Ramstad thrust sheet is represented by a thin unit of pale grey, 216 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

thinly banded, platy, calcite marbles (variety 2, Fig. 5d) which are rather similar to those developed in the wes- tern limb. Although the marble unit sampled along the northern coast of Herjangsfjorden, southwest of Bjerk- vik, is characterised by a limited thickness of <8 m, the rocks show Sr abundances, δ13C and δ18O values (Appendix 2), and 87Sr/86Sr ratios (Appendix 3) similar to those measured from the thicker sections in the wes- tern limb of the Ofoten Synform.

The Evenestangen thrust sheet – The term Evenestangen thrust sheet is here introduced informally to describe a tectonostratigraphic unit consisting of five different varieties of marble: • variety 1 - dark grey, thinly bedded calcite marbles; • variety 2 - variegated, banded, schistose, calcite mar- bles (Leivset type); • variety 3 - white, thickly banded calcite marbles; • variety 4 - subordinate, white, massive, fine-grained dolomite marbles; • variety 5 - rare and sporadic lenses of carbonate conglomerates.

Fig. 6. Isotopic and chemical variations through the lithological The three predominant types of calcite marble (‘Tripar- column of the Ramstad thrust sheet marbles at Fjelldalsheia (do not represent the entire database of the Ramstad thrust sheet shown in tite Unit’ informally introduced by Melezhik et al. Appendences 2 & 3). Note that the erratic increase in δ13C values, 1999) compose the bulk of the Evenestangen thrust which do not correspond with any systematic variations in Mn/Sr sheet and are treated as a single tectonostratigraphic and Mg/Ca ratios, may be associated with a primary stratigraphic unit (see Melezhik et al. 2002a). The unit is developed variation. discontinuously along strike over a distance of 450 km, and it is considered to be a prominent marker unit wit- hin the Uppermost Allochthon in the North-Central Norwegian Caledonides (Melezhik et al. 1999). Based on stratigraphic relationships reported from an area farther north (Bjørlykke & Olaussen 1981), the dark marble forms the stratigraphic base of the unit with the white marble occupying the stratigraphic top (Melez- hik et al. 2002a).

In the western limb of the Ofoten Synform, the ‘Tripar- tite Unit’ is up to 150 m thick and lies structurally upon different marble formations. East of Soltun, the unit rests structurally on dark grey marbles of the Evene- stangen thrust sheet (Fig. 2). At Ramstad, the unit is situated structurally below white marbles of the Ram- stad thrust sheet (Fig. 2). In the eastern limb of the syn- form, the tripartate unit has been documented along the cost of Herjangsfjorden, southwest of Bjerkvik, where it is intensively sheared and has a tectonically Fig. 7. Isotopic and chemical variations through the lithological reduced thickness of less than 5 m. column of the Evenestangen thrust sheet marbles at Evenestangen (do not represent the entire database of the Evenestangen thrust The best known section is located in the western limb sheet shown in Appendences 2 & 3). Note that the considerable nega- at Evenestangen (Fig. 2) where the Evenestangen thrust δ13 tive C shift by 10‰ through the contact between the dark grey sheet has a visible thickness of 150 m (Fig. 7) and shows and variegated marbles is not accompanied by any systematic varia- tions in δ18O and 87Sr/86Sr ratios, implying its primary stratigraphic a stratigraphic inversion. The unit is structurally nature. underlain by white marbles of the Ramstad thrust sheet and overlain by the Tangen schist sequence of Stelten- pohl et al. (1990). Stratigraphically, the section begins with a unit of the dark grey, fine-grained, thinly bedded NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 217 calcite marble (Fig. 5e) followed by the variegated, mica-rich, platy or thickly bedded, calcite marbles (Fig. 5f), and ends with a succession of white, coarsely crys- talline, massive or thickly banded, partly dolomitised calcite marble (Fig. 5g). The dolomite marble is com- monly observed along the contact between the variega- ted and the white calcite marbles, though it also occurs within the white calcite marble. The contact between the dark and the variegated marbles, as observed at Sol- tun south of Evenskjer, is knife-sharp. The dark grey marbles are dolomitised, discoloured and show myloni- tic fabrics within a 10-15 cm-thick zone beneath the variegated marble. The variegated and white varieties are characterised by a transitional relationship with the presence of detached infolds of the variegated marble inside the white marble in a 50 m-thick contact zone. The variegated marbles commonly contain thin, sub- Fig. 8. Isotopic and chemical variations through the lithological concordant layers of chlorite schist and amphibolite column of the Fuglevann Marble at the road-cut (road 19) west of whereas such schist and amphibolite are lacking in the Bjerkvik and north of Herjangensfjorden. Note that the rocks are low black and white marbles. in SiO2 and enriched in TOC.

The dark grey (variety 1), variegated (variety 2) and white (variety 3) calcite marbles composing the Evene- stangen thrust sheet differ in δ13C and 87Sr/86Sr though they show rather similar δ18O values (Appendix 2). In the western limb of the Ofoten Synform, variety 1 is relatively enriched in TOC and characterised by Sr con- centrations ranging from 137 to 1490 ppm. They have positive δ13C values falling between +0.9 and +6.5‰. δ18O is more variable, ranging from 18.5 to 30.8‰ (Appendix 2). Seventeen selected samples analysed for 87Sr/86Sr show ratios ranging from 0.70821 to 0.70887 (Appendix 3). The strongly sheared marble from the eastern limb of the Ofoten Synform, southwest of Bjerk- vik, is characterised by a depletion in 13C and 18O (Appendix 2) and an introduction of 87Sr (Appendix 3).

Variety 2 (variegated calcite marble) is characterised by highly variable Sr concentrations (232 – 8740 ppm), unusually low δ13C values ranging between –10.2 and –6.4‰, and δ18O fluctuating between 14.2 and 26.8‰ (Appendix 2). The shift of >10‰ in δ13C through the Fig. 9. Isotopic and chemical variations through the lithological contact with the dark grey marbles has been documen- column of the Liland marble at Bogen. ted in all studied localities, even though δ18O remains essentially unchanged (cf. Evenestangen section, Fig. 7). The nature and significance of the exceptionally low Thirteen selected samples of the variegated marbles δ13C values in the variegated calcite marbles will be analysed for 87Sr/86Sr fall within the range 0.70824 – considered in a separate paper. However, this striking 0.70869 with one outstanding outlier of 0.71004 isotopic character can be traced over a strike distance of (Appendix 3). The stratigraphic plot (Fig. 7) demon- 450 km, and it is already been used as a chemostrati- strates that the 87Sr/86Sr ratio becomes systematically graphic marker (Melezhik et al. 1999, Melezhik et al. higher with the stratigraphy. Therefore, one can infer submitted). About 100 km north of the study area, the that the observed trend may reflect primary stratigrap- variegated marbles are sandwiched between Early Silu- hic variations. However, with the limited data obtained rian fossiliferous limestones (Bjørlykke & Olaussen from just a single section, one cannot unequivocally 1981) and have almost identical, low δ13C values, rang- substantiate this inference. ing from –10.1 to –8.7‰ (Melezhik et al. 2002a), to those in the Ofoten Synform. Variety 3 (white calcite marble) from both the western and the eastern limbs of the Ofoten Synform are indis- 218 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al. tinguishable from the variegated marbles with regard to (Gustavson 1966) which hosts Mn-Fe sedimentary ores Sr concentrations (399 – 3390 ppm), δ13C (–7.2 to (Foslie 1946). The Hekkelstrand Marble (Gustavson –5.0‰), δ18O (19.4 – 23.2‰, Appendix 2) and 1966) occupies the middle part of the group (Fig. 3), 87Sr/86Sr ratios (0.70870 – 0.70889, Appendix 3). whilst the structurally uppermost marble formation is the Liland marble (Fig. 3) which is also associated with Variety 4 (dolomite marble) is characterised by Sr con- sedimentary Fe-ores (Gustavson 1974). centrations falling between 58 and 97 ppm, and highly variable δ13C and δ18O values ranging from –2.2 to +5.5‰, and from 18.7 to 27.5‰, respectively (Appen- Fuglevann Marble dix 2). The carbon isotopic composition of the dolo- The Fuglevann Marble (Gustavson 1966) is well expo- mite marbles differs from that measured from the host sed in a road-cut north of Herjangsfjoorden, in the eas- calcite marbles. tern limb of the Ofoten Synform (Fig. 2). The approxi- mately 250 m-thick unit consists of dark grey, medium- Variety 5 (carbonate conglomerate) contains pebbles of crystalline, thickly banded calcite marble. A c. 10 m- a white dolomite marble, and pale grey and pink calcite thick unit of calcareous, garnet-mica schists divides the δ13 marble emplaced in a chlorite-calcite matrix. The C marble formation into two sub-units which are approxi- ratio of the pink marble pebble sampled in the Ofot- mately equal in thickness. The structurally upper sub- fjorden district (Appendix 2, Soltun) is close to 0‰. unit contains beds of calcareous mica schists and grap- The beds of pink calcite marbles forming part of the hite schists. Both sub-units contain rare, thin lenses of variegated marbles should therefore not be considered pale grey, finely crystalline dolomite marble (Fig. 8). as a source rock for these conglomerates. Primary sedimentological features are not preserved.

Twenty-five samples collected from the road-cut repre- The Tangen thrust sheet sent the entire thickness of the Fuglevann Marble (Fig. In the western limb of the Ofoten Synform, in the type 8). A further five samples were obtained from several locality at Tangen (Steltenpohl et al. 1990), rare marbles other localities south of Botn (Fig. 2). The calcite mar- occur as thin beds within two-mica schist and ‘garben- bles contain up to 1.2 wt % TOC. The Sr content ranges schiefer’. The marbles are rich in hornblende, strongly from 911 to 2600 ppm. All δ13C values are positive, fal- mylonitised and wedge out to the north. In the eastern ling between +0.1 and +6.3‰. δ18O values fluctuate limb, a c. 70 m-thick unit of dark, banded, calcite mar- between 10.2 and 25.8‰ (Appendix 2). Fifteen selected bles is exposed on the coastal section west of Bjerkvik samples analysed for strontium isotope ratios fall in the (Fig. 2). The calcite marbles occur within a mica schist range 0.70640 to 0.70753 (if the one sample with a high unit which is located structurally below the Bø Quart- 87Rb/86Sr ratio of 0.0112 is excluded, Appendix 3). zite of the Bogen Group. The calcite marble unit is par- tially dolomitised at its structural base and contains several beds of white dolomite marble. Tectonic defor- Hekkelstrand Marble mation has obliterated all primary sedimentological The Hekkelstrand Marble (Gustavson 1966) is poorly features and resulted in the development of a thin com- exposed in the area north of Ofotfjorden. West of Liland positional banding (Fig. 5h). The marbles contain and in the area between Bogen and Botn (Fig. 2), this numerous boudins of amphibolites. unit is represented by pale grey and grey, coarsely crys- talline, impure calcite, and partially dolomitised, calcite Five samples representing the 70 m-thick unit, sampled marbles in several isolated exposures. The Sr content in the eastern limb of the Ofoten Synform, have a signi- shows a large variation (187 to 1080 ppm). All marbles ficant concentration of TOC (0.2 – 0.5 wt%), Sr con- are characterised by a positive δ13C ranging between δ13 centrations ranging 1097 to 1960 ppm, C fluctuating +1.7 and +3.1‰, and wider fluctuating δ18O values, δ18 between +5.5 and +6.4‰, and O values falling wit- 12.7 – 22.2‰ (Appendix 2). 87Sr/86Sr ratios have not hin the range 20.8 to 23.9‰ (Appendix 2). Strontium been measured due to a lack of suitable material. isotope ratios fall between 0.70708 and 0.70738 (Appendix 3). Liland marble The term Liland marble is here introduced informally The Bogen Group to describe a thin marble unit occurring in a series of second-order, closed synforms in the core of the Ofoten The Bogen Group contains three prominent marble Synform (Fig. 2). North of Bogen the marble unit is formations distributed evenly through the sequence more than 25 m thick and lies below the Niingen dominated by diverse schists (Fig. 3). The structurally schists, from which it is separated by a thrust (Stelten- lower calcite marble unit is the Fuglevann Marble pohl & Bartley 1987; Andresen & Steltenpohl 1994). NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 219 O 18 δ ata are from Mon- from ata are D 4 tic precursor. tic precursor. 0.2 n.d. >24 0.02 <0.0001 >22 ≤ ≤ 0.02 0.02 ≤ ≤ Mg/Ca Mn/Sr Rb/Sr ta are from Denison from ta are et al. (1994). Da Mn 3 ata from the area south of the area ata from et Ofotfjordenal. (Melezhik 2002b). D pm ‰ 7 Sr 750-2000 5-350 n.d. n.d. n.d. - 1000-2000 4-200 n.d. n.d. n.d. 24-28 3 O - - 2 Al 2 ata are from Azmy et al.Azmy from ata are (1998). <10 <2 >900 <300 0.32 <0.01 1280 26 0.01 0.023 0.00002 25 D 2 ata are from Melezhik et al. Melezhik from ata are (2001a, 2002a, 2000b). -- -- - 2 mwt %p mwt 25 D n.d.n.d. ? n.d. n.d. - >300 154-966 5-81 ? n.d. <0.02 <0.065 <1.0 n.d. <0.0005 n.d. >20 >50 2.5 0.3 4300 22 0.016 0.005 0.00002 23 >50>50 <0.01 <0.01 5.6 1000 1.1 12 5530 0.01 79 0.012 0.013 0.00005 0.014 22 0.00025 23 >50 <0.01 <0.01 270 10 0.03 0.09 0.00018 24 >0.5 <5 <1.0 >1000 <50 6 3 4 5 7 1 7 2 6 ata are from Derry from ata are et al. (1992), et al. Kaufman (1993). D 5 Geochemical parameters used in low-grade or non-metamorphosed carbonate rocks, brachiopods, and the marble formations studied are included for purposes of comparison. Empirically obtained selection criteria for the 'least altered' strontium isotopic values in high-grade marbles with an aragoni ann Marble 10 4.2 1.1 2640 37 0.01 0.016 0.00008 23 ik nappe complex 1.5 2.0 0.5 1620 41 0.008 0.026 0.00009 24 ev h-grade marbles h-grade marble formations studied rv ade of metamorphism/ contact from Sampling distance gl g ndian non-metamorphosed limestones enestangen thrust sheet ekkelstrand Marble ekkelstrand olocene brachiopods olocene lurian brachiopods hite marble alaeozoic non-metamorphosed shelfalaeozoic limestones angen sequence 2 2.1 <0.01 1690 14 0.015 0.008 0.00008 24 T Fu H Si P Bogen marble 10 <0.01 <0.01 1190 15 0.02 0.013 0.00009 22 Ve Hig Gr material with silica-aluminous rock SiO Ev dark grey marble variegated marble w Cambrian non-metamorphosed limestones H Hi thrust sheetSteinsland Ramstad thrust sheet northernmarbles from area southernmarbles from area >50 4.5 0.15 1790 44 0.06 0.02 0.00009 29 Na ata are from Lowenstam (1961), Lowenstam from ata are (1968),Vogel Dittmar & et al. Frank (1982), (1994). and Grossman able 1. T D tañez et al. (1996). ‘–’ non relevant. n.d.’ – not determined. 1 220 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al. ∗ ∗ ♦ ♦ ∗ ♣ ♥ 440-430 440-430 525, 475-460, 525, 475-460, the age constraints provided and brachio- by corals values projected onto the seawater curve onto the seawater values projected (Fig. 11). 465, 430 - 400

♦ Sr 86 Sr/ 87 ,Ma Sr C reference curve;C reference 13 δ Age 650 650 Curve 1 Curve 2 Over the range 790-650 MaOver Outside the range age, Proposed Ma 1 the further time constraints provided by ♣ Sr Sr, ppm - Apparent depositional the least altered ages obtained from Apparent - 86 Sr the constraints provided by the lower age limit of deformation (437 Ma, et al. Tucker 1990). Sr/ e Curve 2; e Curve initial 790-650 Ma ♥ 87 Sr ratio. Age Sr referenc 86 O 86 18 Sr/ δ Sr values and corresponding apparent depositional ages of the marble formations studied in the area Sr/ 87 87 86 Sr/ C 87 13 ‰‰ -5.9 23.2 0.70870 4300 575 – 520, 500 - 437 -8.3 26.8 0.70824 5530 580-555, 540- 440-438 +6.5 27.7+3.1+6.3 22.2 0.70655 25.8 1200 n.d. 0.70640 755-730, 690- 2600 785, 760 660 650-595 650-595 660 +6.4 23.9 0.70708 1700 725, 700 620 595-585 595 +6.0 23.6 0.70729 1600 725, 700 585 ? +6.0 30.8+0.2 0.70821+6.0 24.8 29.0 1000 0.70920 0.70677 268 1800 755-730, 690- 580-555, 540- 650-595 440-438 520-500 650-595 515ß δ O, 18 δ C, 13 δ parent depositionalparent based on ages are marble oup

Ap ∗ north of Ofotfjorden. The least altered Gr ik nappe complex marbleik nappe complex vann Marble marble age - e mation rv gl enes nappe complex enestangen thrust sheet marble ekkelstrand Marble angen thrust sheet marble concentration corresponding to the initial in the rock For H Fu Bogen Bogen Liland marble Na Ev T Ev White marble Dark Variegated Ramstad thrust sheet marble thrustSteinsland sheet marble

able 2. T Sr Proposed 1 pods (Bjørlykke & Olaussen 1981), for detailet seeal. Melezhik (2002a); NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 221

The marble is pale grey and dark grey in colour, mas- Rb/Sr, as well as carbon and oxygen isotopes, are widely sive, thin- to thick-banded, and cut by numerous veins used as geochemical criteria for detecting the least dis- and dykes of felsic igneous rocks. Boudins of amphibo- turbed carbon, oxygen and Rb-Sr systems. Different lites are abundant (Fig. 9). Very rare, white, fine-grai- authors, however, use not only dissimilar values of the ned dolomite marbles occur as small lenses. same ratios, but also dissimilar combinations of these ratios (Asmerom et al. 1991; Derry et al. 1992; Kaufman Thirteen samples of calcite marble collected from a et al. 1993; Semikhatov et al. 1998). In all cases the small quarry at Bogen and road-cuts at Liland (Fig. 2) choice of the elemental ratios and their values is empi- have Sr contents fluctuating between 431 and 1810 rical and to some extent arbitrary (Table 1). ppm, a positive δ13C falling between +2.1 and +6.5‰, and δ18O values ranging between 14.6 and 27.7‰ Conventional geochemical assessment of post-depositi- (Appendix 2). The strontium isotope ratios fall within a onal alteration of carbonate has been refined for high- limited range of 0.70655-0.70713 (Appendix 3). grade rocks (Melezhik et al. 2001a, 2002a). Table 1 shows that the level of screening criteria chosen for the high-grade rocks is either equal to or significantly hig- her than that used for non-metamorphosed rocks. In Geochemical screening against addition, the Mg/Ca ratio has been found to be a very post-depositional resetting of sensitive parameter for identifying disturbance of the Rb-Sr system in high-grade marbles, although the C, O and Rb-Sr isotope systems application of this parameter to non-metamorphosed Depending on metamorphic conditions and the chemi- limestones has been very rarely discussed in the publis- cal composition of carbonate rocks, their pre-metamor- hed literature. Oxygen isotopes, being sensitive indica- phic carbon, oxygen and strontium isotopic values tors of even minimal alteration, are not always useful could either be overprinted (Nabelek 1991; Romer 1994; parameters for screening disturbance of the more resis- Bickle et al. 1995, 1997; Lewis et al. 1998) or preserved tant strontium isotope system in both non-metamor- even under amphibolite-facies conditions (Ghent & phosed limestones (Bickle & Chapman 1990; Bickle O’Neil 1985; Baker & Fallick 1988, 1989a, 1989b; Wick- 1992; Jones et al. 1994; Montañez et al. 1996) and high- ham & Peters 1993; Boulvais et al. 1998; Melezhik et al. grade marbles (Melezhik et al. 2001a, 2002a, 2002b). In 2001a). Diagenetic and metamorphic alterations affect the high-grade marbles, quite commonly there is nega- carbonate material in a similar way (Nabeleck 1991). tive correlation between δ13C values and TOC concen- 12 These processes lower δ13C and δ18O, and introduce trations, suggesting the incorporation of C-rich CO2, radiogenic strontium. In general, during post-depositi- derived from oxidation of organic matter, into newly onal, open-system recrystallisation, the δ13C of calcite formed carbonates. Consequently, a δ13C vs TOC plot and dolomite would be buffered by the dissolving pre- is useful for screening carbon isotope values. cursor, while the δ18O, Mn and Sr contents would be partially shifted towards equilibrium with the ambient Even if all necessary geochemical, mineralogical and diagenetic fluids. This is because the sediment/water petrological precautions have been taken to identify ratios of diagenetic/metamorphic systems (cf. Banner & alteration effects, a limited number of samples and ana- Hanson 1990) are about 101 :102-103 :104 for oxygen, lyses are considered to be insufficient even to recognise trace elements and carbon, respectively (cf. Land 1992). alteration trends and therefore should not be used for the reconstruction of δ13C, and particularly 87Sr/86Sr As the rocks studied are polymetamorphosed, normal ratios, in both low- and high-grade carbonate rocks. petrographic screening and cathodoluminescence was of very limited use as they could only detect the alter- In our study, 315 samples of calcite and dolomite mar- ation associated with the last geochemical transforma- bles representing all major marble units of the Narvik, tion. Thus, although all traditional screening procedu- Evenes and Niingen nappe complexes, and the Bogen res, originally specified for low-grade rocks (Brand & Group, were analysed for major and trace elements, and δ13 δ18 Veizer 1980; Veizer 1983, and later revisions; Banner & 232 samples for Ccarb and Ocarb ratios. The Hanson 1990; Kaufman & Knoll 1995; Azmy et al. 1998; 87Sr/86Sr ratios were measured on 105 selected samples. Jacobsen & Kaufman 1999), have been applied, the dis- It is important to emphasise that the geochemical cha- crimination technique has been based essentially on racteristics of the studied high-grade marbles suggest a geochemical criteria. much higher level of preservation of the strontium and carbon isotope systems compared with non-metamor- Conventional geochemical assessment of post-depositi- phosed limestones (Table 1). Amazingly, Sr and Mn onal alteration of carbonate is largely based on relative abundances in marbles correspond to those in non- abundances of Mn, Fe, Rb and Sr (e.g. Brand & Veizer metamorphosed brachiopods (Table 1). The only 1980). Elemental ratios, such as Mn/Sr, Fe/Sr, Ca/Sr and exception is that of the marbles of the Ramstad thrust sheet which have lower Sr and higher Mn contents and 222 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al. 660 650-595 550-500 440-438 620-610 440-438 710-700 or 660 ♣ ♦ ♦ ♣ ♦ ♦ ♦ Sr region, Ma 86 Sr/ 87 515 550-500 660 650-595 595 620-610 n.d. 710-700, 660 oposed Proposed the entire Ofoten 650-595 650-595 440-438 440-438 Pr ♦ ♦ ♣ ♦ ♦ ♣ Sr 86 Sr/ 87 Sr 86 n.d. 0.70615 Sr/ initial initial age, Ma 0.70677 0.70663 0.70920 0.70878 0.70640 0.70645 0.70821 0.70826 0.70708 0.70720 0.70824 n.d. 440-438 440-438 87 ata from Melezhik et al. Melezhik ata from et al. (2002a) and Melezhik (2002b), respectively. ‘ - ’ – formation/data not are D Sr values, and the corresponding apparent depositional ages for ♦ ♦ ♣ ♦ ♦ ♦ ♣ O ♣ 86 , 18 ♦ δ Sr/ 87 O 18 ‰‰ 29.0 21.9 24.8 23.3 25.8 26.0 30.8 20.9 23.9 23.7 26.8 22.6 22.2 25.5 δ O and 18 δ ♦ ♦ ♣ ♦ ♦ ♣ ♦ C, C 13 13 δ δ C 13 ‰‰ N* S* N S N S N S ages for Proposed -8.3 -8.5 -5.9 - 23.2 - 0.70870 - c. 437 - c. 437 +6.0 +5.0 +0.2 +2.2 +6.3 +6.5 +6.0 +5.0 +6.5 - 27.7+6.4 +8.0 - 0.70655 - 650-595 - 650-595 +6.0 n.d. 23.6 n.d. 0.70729 n.d. ? n.d. +3.1 +5.0 δ ) in S in S) in S) marble oup

correlative tectonostratigraphic units in the areas north and south of Ofotfjorden. Inconsistencies between the least altered Gr ik nappe complex marbleik nappe complex vann Marble marble (Formation III marble (Formation

e mation I mation II mation r rv rk enes nappe complex gl enestangen thrust sheet marble ekkelstrand Marble angen thrust sheet marble For Fo ( Steinsland thrustSteinsland sheet marble ( Ramstad thrust sheet marble Fu Ev White marble Variegated Da For Bogen Bogen Liland marble Ev T Na H able 3. ailable. ‘ n.d. ’ – not determined. T N, et al. north and south (Melezhik S – areas (this study) 2002, 2003) of Ofotfjorden. ∗ av NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 223 greater Mg/Ca ratios relative to other marbles. Howe- hik et al. 2000), and have thus been useful as a tool for ver, the δ18O value does not suggest a significant alter- broader chemostratigraphic correlation. The applica- ation, and the Sr concentration falls within the range of tion of the concept of principal chemostratigraphic Cambrian limestones (Table 1). Tentatively, these markers has indeed provided a breakthrough in under- geochemical characteristcs have been assigned to the standing of the geology in the Ofoten area. As well as calcite precursor, whereas other Sr-rich marble forma- revealing stratigraphic heterogeneity and tectonic repe- tions had an aragonitic protolith. tition in the Evenes nappe complex, these marker hori- zons have also helped to provide a reliable stratigraphic The ‘least altered’ carbon, oxygen and strontium iso- subdivision of a marble succession (Fig. 3) that previ- tope ratios, selected by using multiple criteria (Table 1, ously was considered to represent a continuous, homo- high-grade marbles) with the additional aid of different geneous and coherent unit, the Evenes Group (Andre- cross-plots, are represented in Table 2. sen & Steltenpohl 1994). Combined with new geologi- cal mapping, the marker horizons have thus allowed us to produce what is essentially a new geological map (Fig. 2). Chemostratigraphic correlation and stratigraphic subdivision Short-distance geological correlations in the study area Apparent depositional ages of the are facilitated by a few lithostratigraphic markers which carbonate formations based on isotope have previously been used to trace units across Ofoten- fjorden within the Ofoten Synform. Among them, the chemostratigraphy Bø Quartzite (Figs. 2 & 3) is the most prominent litho- Isotope chemostratigraphy: general considerations stratigraphic marker because it has a persistent thick- δ13 87 6 ness and a considerable lateral extent (Gustavson Secular variations of Ccarb and Sr/8 Sr in Neo- 1974c). The stratabound Fuglevann Mn-Fe ores can proterozoic and early Lower Palaeozoic seawater have also be used as a marker horizon, although their rather previously been tested for the purpose of ‘isotope che- sporadic appearance makes them less valuable for pur- mostratigraphy’ by their application to indirect dating pose of correlation. Besides, in the Ofotfjorden area of carbonate sedimentation where no additional strati- there are two tectonostratigraphic units containing graphic control is provided (Melezhik et al. 2001b, and Mn-Fe ores, and it is not entirely clear whether they references therein). There is a high degree of inconsi- δ13 represent two different stratigraphic units or only one stency between the various Ccarb-age curves for sea- unit tectonically repeated. However, these particular lit- water which have been constructed by different authors hostratigraphic markers cannot be used for the detailed (Fig. 10, Melezhik et al. 2001b). Therefore, in the stratigraphic subdivision of marble formations. absence of other constraining information, carbon iso- topes cannot be used for high-precision Neoprotero- The results of our study show that the marble formati- zoic correlation (Kaufman & Knoll 1995). ons investigated in the area north of Ofotfjorden are distinguished by different lithological characteristics Strontium isotope stratigraphy has the potential to pro- and contrasting δ13C and δ18O values, 87Sr/86Sr ratios vide better indirect dating of Neoproterozoic sedimen- and Sr abundances (Table 2), thus offering a new possi- tary carbonates because of the gradual and regular 87 86 bility for chemostratigraphic correlations. A prominent increase in Sr/ Sr from 800 to c. 550 Ma (Fig. 11); chemostratigraphic marker is the ‘Tripartite Unit’ of and also because Sr has a large residence time relative to 87 86 the Evenestangen thrust sheet. This is characterised by seawater, resulting in a uniform Sr/ Sr ratio in sea- its unique combination of colours (Fig. 5e-g,) which water at any given time (Veizer et al. 1997). However, can easily be identified and traced in the field, and by sampling of carbonate sequences through Neoprotero- the unusual combination of very high and very low car- zoic time remains incomplete and because of this there bon isotope ratios (Tables 1 & 2). have been several disagreements among investigators, particularly about the portion of the 87Sr/86Sr curve The Ramstad marble unit is another chemostratigrap- from 790 to 650 Ma (Curve 1 vs Curve 2, Fig. 11). For hic marker because of its white, rather massive charac- reasons explained in Melezhik et al. (2001b), Curve 2 is ter and particularly by its very uniform δ13C value, used for constraining apparent depositional ages. fluctuating around zero, coupled with a low Sr content and highly radiogenic initial strontium isotope ratio. Despite all the complications involved, by combining strontium (Curve 2, Fig. 11) and carbon (Fig. 10) iso- Both these markers have already been recognised in tope stratigraphy, several discrete ages within the 590- several other areas outside the Ofoten Synform (Melez- 545 Ma interval, and two age-groups at 660-610 and 740-690 Ma can be resolved in Neoproterozoic and 224 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Fig. 10. Temporal trends of δ13C in seawater (after Melezhik et al. 2001b). Upper panel: A series of conflicting δ13C calibration curves recon- structed for the Neoproterozoic. The least altered δ13C values measured from marbles of the Bogen Group, the Narvik nappe complexe, and the Tangen and Steinsland thrust sheets of the area north of Ofotfjorden are shown by horizontal lines. Lower panel: δ13C calibration curve recon- structed by Veizer et al. (1999) from Cambrian to Devonian time; the shaded area around the running mean (solid line) includes 68% (grey) and 95% (pale grey) of all published data. δ13C age curves for Neoproterozoic time are based data reported by different authors after 1998. The new age for the Cambrian-Ordovician boundary is based on Davidek et al. (1998). The least altered δ13C values measured from marbles of the Evenestangen and Ramstad thrust sheets of the area north of Ofotfjorden are shown by horizontal lines. NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 225 early Palaeozoic time, even if no additional stratigrap- limit of sedimentation (Tucker et al. 1990; Northrup hic control is provided (Melezhik et al. 2001b). 1997). The new isotope data Melezhik et al. (2002a) demonstrated that the dark and variegated marbles of The apparent depositional ages of the studied carbona- the Evenestangen thrust sheet have strontium and car- tes have been constrained by projection of the ‘least bon isotope ratios very similar to those measured from altered’ isotopic values obtained from the marble for- the Llandovery limestones of the Mosberg Formation at mations onto the seawater curves. The time when both Sagelvvatn (Bjørlykke & Olaussen 1981). Consequently, the δ13C and the 87Sr/86Sr intercepts are in agreement the youngest age group of c. 440-438 Ma matches the has been considered to represent an apparent depositi- Early Silurian (Llandovery) biostratigraphic age. onal age (Figs. 10 & 11). The age data over the most controversial time interval, 790-650 Ma, are shown in The strontium isotope ratios measured from the varie- separate columns for Curves 1 and 2 (Table 2), and out- gated calcite marbles are very similar to those of the side this range they are shown in a third column. dark grey marble (Fig. 11). For the reasons explained above, their apparent depositional age can be constrai- ned to the Early Silurian, given that the dark limestones Apparent depositional ages of the Narvik nappe complex and the variegated marbles at Sagelvvatn have a normal The very limited isotopic data obtained from the dis- stratigraphic relationship, as reported by Bjørlykke & continuous, thin marble unit can only be used for con- Olaussen (1981). Based on the slope of the Silurian 87 86 straining a minimum depositional age, because it is not Sr/ Sr reference curve (Fig. 11), and on the fact that 87 86 clear whether the strontium and carbon isotopic values Sr/ Sr ratios of the variegated marble are slightly can be considered to be a proxy to the depositional iso- higher (0.70824) than those of the dark grey marble topic signature. Both the 87Sr/86Sr ratios and the δ13C (0.70821), the former should have been deposited values are consistent with a Neoproterozoic age (Table somewhat later. However, the age difference cannot be 2) falling either within the time interval 725-700 Ma resolved just by means of isotope chemostratigraphy. (Curve 1, Fig. 11) or at 585 Ma (Curve 2, Fig. 11). Although a Llandovery age is suggested for the variega- 13 However, because of the uncertain tectonostratigraphic ted calcite marbles, their C-depleted nature is not position of the marble, it is not clear at the present time entirely consistent with the carbon isotope composi- whether the obtained ages characterise the basal unit of tion reported from this time interval (Fig. 10). the Evenes nappe complex or the upper part of the Nar- vik nappe complex. The best-preserved strontium isotope ratio measured from the white calcite marbles (0.70870) is higher as compared to that of the dark and variegated marbles Apparent depositional ages of the Evenes nappe complex (Fig. 11). This value is consistent with three age-groups: 570-520, 500-465 and 430-400 Ma (Fig. 11). The first 87 86 Steinsland thrust sheet – The Sr/ Sr values of the two age-groups should not be considered because the Steinsland marble intercept the reference curves at 755- white marble lies stratigraphically above the dark grey δ13 730, 690-650 and 690-595 Ma. The least altered C and variegated marbles. A further time constraint is pro- value cannot provide a further time constraint (Fig. vided by the upper age limit of 437±1 Ma for the meta- 10). However, as the two first ranges are based on the morphism and deformation of the Narvik Group rocks less reliable Curve 1 (see Melezhik et al. 2001b, Fig. 11), (Tucker et al. 1990; Northrup 1997). Consequently, the the 650-595 Ma time interval is considered to be a apparent age of the white marble is c. 437 Ma. proxy for the age of carbonate sedimentation. Tangen thrust sheet – Projection of the least altered Ramstad thrust sheet – The strontium isotope data sug- 87Sr/86Sr value of the calcite marbles onto the seawater gest that the marble protolith was deposited during the reference curve (Fig. 11) is consistent with several ages period 520-500 Ma (Fig. 11). The carbon isotope or age-groups: 725, 700, 620 and 595-585 Ma (Table 2). records are most consistent with an age of approxima- A further constraint can be provided by the high δ13C tely 515 Ma (Fig. 10), which is thus considered to be the of +6.4‰, because this excludes ages younger than 595 apparent depositional age of this marble unit (Table 2). Ma (Fig. 10). If the less reliable 87Sr/86Sr Curve 1 is dis- regarded (Fig. 11), the dates of 725 and 700 Ma are also Evenestangen thrust sheet – The least altered strontium considered as less probable. Thus, 595 Ma is considered isotope ratios obtained from the dark grey calcite mar- the best approximation for the age of Tangen carbonate bles are consistent with several time intervals, 580-555, sedimentation. 540-525, 475-460 and 440-430 Ma (Fig. 11, Table 2). The interval 475-460 Ma, representing the Middle Ordovician, should be disregarded because it is not Apparent depositional ages of the Bogen Group consistent with the high δ13C values (Fig. 10). A further 87 86 time constraint is provided by the c. 438 Ma upper age Fuglevann Marble – The Sr/ Sr data are consistent 226 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al. with three discrete ages, 785, 760 and 660 Ma (Fig. 11, Uncertainties of indirect dating by Table 2). The carbon isotopes, however, do not support 785 Ma (Fig. 10). Consequently, the apparent depositi- means of isotope stratigraphy in the onal age of this marble may be constrained to 660 if Ofotfjorden area Curve 2 is used. The limitations and uncertainties of indirect dating by Hekkelstrand Marble – In the study area, the Hekkel- strontium and carbon isotope stratigraphy of the high- strand Marble is represented by impure marble litholo- grade marble sequences in the study area can be asses- gies. This makes it impossible to obtain strontium iso- sed by comparison with the isotopic data and indirect tope analyses which can be used for the assessment of dates obtained for the correlative units which have been apparent depositional ages. An extensive isotopic study sampled in several sections elsewhere in the region. of the Hekkelstrand Marble has recently been reported Comparison of correlative sections across the fjord is from the area south of Ofotfjorden. This study conclu- one of the possibilities because key geochemical profi- ded that this particular marble unit has a depositional les, representing marbles of the Steinsland, Evene- age of either 710-700 or 660 Ma (Melezhik et al. 2002b). stangen (black and variegated marbles), Ramstad and Fuglevann units in the area south of Ofotfjorden Liland marble – This marble has least altered 87Sr/86Sr (Melezhik et al. 2002, 2002b), are separated from those ratios and δ13C values that are similar to those measu- sampled in the northern area by a distance of 20-30 km red from the Steinsland marbles (Table 2). Accordingly, (Fig. 2). Table 3, summarising the database for the the apparent depositional age for this unit can be con- entire area, shows that several correlative units are cha- strained to the 650-595 Ma time interval. racterised by varying degrees of inconsistency in isoto- pic data and apparent depositional ages.

Fig. 11. Temporal trends of 87Sr/86Sr in seawater (after Melezhik et al. 2001b) and apparent depositional ages of the investigated carbonate for- mations. This shows the 87Sr/86Sr age curves reported in the literature with projections (horizontal lines) of the least altered 87Sr/86Sr values of marbles from the area north of Ofotfjorden. The new age for the Cambrian-Ordovician boundary is based on Davidek et al. (1998). See Mele- zhik et al. (2001b) for explanation of Curves 1 and 2. NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 227

The ‘least altered’ δ13C values obtained from the corre- rently deposited over a wide period of time. The two lative formations, which were sampled in several, far- oldest marble units, one located in the Steinsland separated localities, show very limited differences wit- thrust sheet and the other in the Tangen thrust sheet, hin 0.2 – 2.0‰ (Table 3). These differences might have are inferred from 87Sr/86Sr and δ13C data to have been been caused by at least four factors, such as (i) natural deposited during the late Neoproterozoic between 650 variations in seawater; (ii) diagenetic/metamorphic and 595 Ma, and between 620 and 610 Ma, respectively. isotopic disturbance, (iii) biased sampling, and (iv) Importantly, the Steinsland thrust sheet occupies the incomplete sections sampled in different areas. The structural base, whereas the Tangen thrust sheet is loca- greatest inconsistency of c. 2‰ is associated with the ted at the structural top of the Evenes nappe complex Ramstad and Hekkelstrand Marbles. In the case of the (Figs. 2 & 3). Of the marbles in the middle part of the Ramstad marble, factors (iii) and (iv) are favoured carbonate sequence, those in the Evenestangen thrust because the section sampled in the southern area (For- sheet have an apparent depositional age of c. 440-437 mation II) has a limited visible thickness of just a few Ma.The marbles of the Ramstad thrust sheet, on the metres, whereas the section sampled in the northern other hand, are inferred to have been deposited in Late area shows a thickness of more than 200 metres (Fig. Vendian-Cambrian time, between 550 and 500 Ma. 6). A similar explanation can be given for the geoche- mical inconsistency associated with the Hekkelstrand Accepting the age assignments inferred for the carbo- Marble, because in the northern area it has been sam- nate formations, it follows that the former Evenes pled from a few separate localities, whereas in the sout- Group does not represent a coherent lithostratigraphic hern area the complete, 40 m-thick section is exposed unit (Melezhik et al. 2002a) as has been suggested ear- in a quarry (Melezhik et al. 2002b). lier (Andresen & Steltenpohl 1994). Instead, the isotope data suggest that it is composed of tectonically imbrica- The ‘least altered’ 87Sr/86Sr ratios obtained from the ted marble formations of diverse age groups that were correlative formations show differences within 0.00005 emplaced in a non-chronostratigraphic order (Fig. 3). – 0.00014 with one exception (Table 3). This exception The new geochemical data obtained in this study thus is the Ramstad marble (Formation II in the southern corroborate our earlier suggestion (Melezhik et al. area) in which the ‘least altered’ 87Sr/86Sr ratios obtai- 2002a) that the term Evenes Group should be abando- ned from two separate localities differ by 0.00042. Con- ned and, except for the subjacent ophiolite fragment, be sidering the overall lower Sr concentrations in the replaced by the designation Evenes nappe complex. In Ramstad marbles from the northern area (up to 370 this regard, it was earlier suggested (Boyd & Søvegjarto ppm) with respect to Formation II sampled in the sout- 1983; Boyd et al. 1986), and has recently been docu- hern area (up to 770 ppm, Melezhik et al. 2002a), the mented (Melezhik et al. 2002) and then confirmed by alteration scenario is a very likely explanation for the this study, that the basal, Vendian-age, Steinsland mar- observed inconsistency (Table 3). However, the obser- bles are separated from the structurally lower, Early to ved discrepancy in 87Sr/86Sr ratios is within the appa- Mid Ordovician ophiolite fragment (c. 469-470 Ma; rent depositional age suggested by either of the two Oliver & Krogh 1995) and the Elvenes Conglomerate values (Table 3). (the Bjerkvik Nappe) by a tectonic contact (Fig. 3).

In summary, the small inconsistencies registered in the Additional tectonic contacts should also be invoked in 'least altered' isotopic values along strike in the Ofot- order to reconcile the apparent disparity in age between fjorden region in any one correlative marble unit have the Steinsland (650-595 Ma), Ramstad (550-500 Ma), no detectable effect on the interpreted apparent deposi- Evenestangen (440-437 Ma) and Tangen (620-610 Ma) tional ages of these units (Table 3). thrust sheets (Fig. 3). Other alternatives for relations- hips between the first three units, though less viable, are either to infer depositional hiatuses, each lasting for 50- 60 million years, or to suggest the presence of conjunc- Geological implications of apparent tive extensional faults. The thrust contact between the depositional ages Evenestangen and Tangen thrust sheets, however, is unavoidable considering the age relationships and the Stratigraphy 170 Ma time gap involved between the deposition of Carbon and strontium isotope data strongly suggest these two units (Fig. 3). that deposition of the Fuglevann, Hekkelstrand and Liland carbonate formations of the Bogen Group Geological relationships indicate that the proposed tec- occurred in the late Neoproterozoic, sometime between tonic contacts were comparatively early phenomena in 710 and 595 Ma. The Late Ordovician-Early Silurian the geological history of the region, and that all these Evenes Group of Andresen & Steltenpohl (1994) con- faults were affected by later episodes of deformation sists of several marble formations which were appa- and associated metamorphic recrystallisation. Because marbles, in general, have an extremely high propensity 228 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al. for being recrystallised during even the latest tectono- Conclusions metamorphic episodes, they rarely retain fabrics associ- ated with earlier thrusting events. This could, perhaps, Isotope chemostratigraphy combined with a detailed have been a reason why the layer-parallel conjunctive mapping of non-fossiliferous, high-grade, polydefor- fault contacts were not recognised during previous med, marble sequences represent progress towards a structural investigations. The tectonic emplacement of new generation of geological maps in metamorphic ter- Neoproterozoic formations upon rocks of Mid Ordovi- ranes. The isotope chemostratigraphy has been shown cian to Early Silurian age is easy to relate to Scandian to have a high potential for quantitatively-based chron- orogenic deformation; but the tectonic processes stratigraphic subdivision and for geological correlation responsible for the juxtaposition of Neoproterozoic of high-grade marble successions. and Cambrian rocks may well relate to a Mid to Late Ordovician, Taconian orogenic event (Roberts et al. The real breakthrough with the new geological map- 2002; Melezhik et al. 2002a). ping has been in the establishment and use of the Cam- brian and Early Silurian chemo/chronostratigraphic Finally, the detailed geological mapping in combination markers that reveal stratigraphic heterogeneity and tec- with the isotope study suggest that the Ofoten Synform tonic repetition, provide a reliable stratigraphic subdi- preserves a complex, tectonically dissected package of vision and facilitate the compilation of chronologi- rocks (Fig. 3). The isotope data helped to provide a reli- cally-based geological map. The same markers have able chronostratigraphic subdivision of the marble for- made it possible to link commercially exploited dolo- mations and thus allowed us to produce a chronologi- mite and calcite marble deposits with chronostrati- cally-based geological map (Fig. 2). graphy.

Mineral exploration – There are five commercially The thick succession of calcite and dolomite marbles of exploited dolomite deposits in Norway, all located in the Ofoten Synform has previously been considered to the county of Nordland. Within the study area the Hek- be a stratigraphically homogeneous assemblage of Late kelstrand deposit, hosted by the Hekkelstrand Marble Ordovician-Early Silurian age. However, this interpre- formation, is considered to be the most valuable (Karl- tation is at variance with the isotopic evidence for a sen 1998b). The inferred Neoproterozoic depositional complex tectonic imbrication of polymetamorphosed age of the host calcite marbles (Melezhik et al. 2002b) and polydeformed, Neoproterozoic, Cambrian and provides prospectors with stratigraphic constraints. Early Silurian carbonate formations. Some layer-paral- Consequently, the Late Ordovician-Early Silurian mar- lel tectonic contacts may now be difficult or impossible bles that are widely developed in the study area and far- to detect because of pervasive recrystallisation of the ther north, hold little potential for this kind of dolo- carbonate rocks mite deposit. Thus, the search for new deposits of the Hekkelstrand type should be restricted either to the Hekkelstrand Marble in the Ofoten district or to its known or inferred stratigraphic equivalents in other Acknowledgements: - The fieldwork for these investigations was sup- areas of the Uppermost Allochthon of the Norwegian ported by the Geological Survey of Norway (NGU) (Projects 270501, Caledonides. 270502, 270503, 270504 270510 and 270519). The laboratory work and isotope study was financed by NGU (Projects 270503, 270504 270510 and 270519), the Scottish Universities Environmental Research Centre Geological mapping and isotope chemostratigraphy and Russian Foundation for Basic Research Projects 02-05-65241 and shows that the northern part of the Ofotfjorden area 03-05-65040. The help of G.V. Konstantinova, N.N. Melnikov and E.P. may have a significant potential for Cambrian, dolo- Kutyavin in the Rb-Sr analytical work is greatly appreciated. T.L. Tur- mite marble deposits that occur as lenses within the chenko provided the results of the XRD analysis for the siliciclastic constituents of the carbonate rocks. The C and O isotope analyses were Ramstad thrust sheet. The isotopic data (Tables 1 & 2) performed at the Scottish Universities Environmental Research Centre suggest that the Ramstad dolomite marbles are identi- supported by the Consortium of Scottish Universities and the Natural cal to the Hammerfall-Løgavelen dolomite marbles Environment Research Council. C. Thomas and another referee are (Melezhik et al. 2000), commercially exploited in the thanked for timely, very detailed and constructively critical reviews of Fauske area c. 100 km to the south (Fig. 1). The detailed the manuscript. Ø. Nordgulen is thanked for making the final version of the article more intelligible and concise. mapping has also revealed a new type of calcite marble deposit, again in the Ramstad thrust sheet. This Cam- brian calcite marble is characterised by a considerable thickness (Fig. 6), high purity (Appendix 2) and mas- sive appearance. Given all these properties, the marble may be considered as a potentially valuable raw mate- rial for industrial use either as a dimensional stone or in the paper industry. NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 229

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E. & Pokrovsky, B.G.: Enigmatic nature of Podkovyrov, V.N. & Kislova, I.V. 1998: The strontium isotopic thick sedimentary carbonates depleted in 13C beyond the canonical composition in early Late Riphean seawater: Limestones of the mantle value: the challenges to our understanding of the terrestrial Lakhanda Group, the Uchur-Maya region, Siberia. Transactions carbon cycle. Precambrian Research (submitted) (Doklady) of the Russian Academy of Sciences / Earth Science Secti- Melezhik, V.A., Gorokhov, I.M., Fallick, A.E. & Gjelle, S. 2001a: Stron- ons, 360, 488-492. tium and carbon isotope geochemistry applied to dating of carbo- Steltenpohl, M.G. 1987: Tectonostratigraphy and tectonic evolution of nate sedimentation: an example from high-grade rocks of the Nor- Skånland area, North Norway. Norges geologiske undersøkelse Bulle- wegian Caledonides. Precambrian Research 108, 267-292 tin 409, 1-20. Melezhik, V.A., Gorokhov, I.M., Fallick, A.E., Roberts, D., Kuznetsov, Steltenpohl, M.G., Andresen, A. & Tull, J.M. 1990: Lithostratigraphic A.B., Zwaan, K.B. & Pokrovsky, B.G. 2002a: Isotopic evidence for a correlation of the Salangen (Ofoten) and Balsfjord (Troms) complex Neoproterozoic to Silurian rock assemblage in the North- Groups: evidence for post-Finnmarkian unconformity, North Central Norwegian Caledonides. Precambrian Research 114, 55-86. Norwegian Caledonides. Norges geologiske undersøkelse Bulletin Melezhik, V.A., Gorokhov, I.M., Fallick, A.E., Roberts, D., Kuznetsov, 418, 61-77. A.B., Zwaan, K.B. & Pokrovsky, B.G. 2002b: Isotopic stratigraphy Steltenpohl, M.G. & Bartley, J.M. 1984: Kyanite-grade metamorphism suggests Neoproterozoic ages and Laurentian ancestry for high- in the Evenes and Bogen groups, Ofoten, North Norway. Norsk grade marbles from the North-Central Norwegian Caledonides. Geologisk Tidsskrift 64, 21-26. Geological Magazine 139, 375-393. Steltenpohl, M.G. & Bartley, J.M. 1987: Thermobarometric profile Melezhik, V.A., Gorokhov, I.M., Kuznetsov, A.B. & Fallick, A.E. 2001b: through the Caledonian nappe stack of western Ofoten, North Chemostratigraphy of the Neoproterozoic carbonates: implicati- Norway. Contributions to Mineralogy and Petrology 96, 93-103. ons for ‘blind dating’. Terra Nova 13, 1-11. Tucker, R.D., Boyd, R. & Barnes, S.J. 1990: A U-Pb zircon age for the Melezhik, V.A., Gorokhov, I.M., Fallick, A.E., Roberts, D., Øvereng, O., Råna intrusion, N. Norway: new evidence of basic magmatism in Zwaan, K.B., Gjelle, S., Lindahl, I. & Ovchinnikova, G.V. 1999: Car- the Scandinavian Caledonides in Early Silurian time. Norsk Geolo- bonate rocks of Norway: exploration philosophy based on rese- gisk Tidsskrift 70, 229-239. arch. (abstract). EUG 10 Journal of Conference Abstracts 4, 492. Tull, J.F., Bartley, J.M., Hodges, K.V.,Andresen, A., Steltenpohl, M.G. & Melezhik, V.A., Heldal, T., Roberts, D., Gorokhov, I.M. & Fallick, A.E. White, J.M. 1985: The Caledonides in the Ofoten region (68°-69° 2000: Depositional environment and apparent age of the Fauske N), north Norway: key aspects of tectonic evolution In Gee, D.G. & carbonate conglomerate, North Norwegian Caledonides. Norges Sturt, B.A. (eds): The Caledonide Orogen – Scandinavia and Related geologiske undersøkelse Bulletin 436, 147-168. Areas, 553-568. John Wiley & Sons Ltd., Chichester. Melezhik, V.A., Sørdal, T. & Øvereng, O. 1997. Dolomite marble Trønnes, R.G. & Sundvoll, B. 1995: Isotopic composition, deposition potential in the Ofotfjord area. Norges geologiske undersøkelse ages and environments of Central Norwegian Caledonian marbles. Report 97.184, 29 pp. Norges geologiske undersøkelse Bulletin 427, 46-47. Montañez, I.P.,Banner, J.L., Osleger, D.A., Borg, L.E. & Bosserman, P.J. Veizer, J. 1983: Trace elements and isotopes in sedimentary carbonates. 1996: Integrated Sr isotope variations and sea-level history of In Reeder, R.J. (ed.): Carbonates: Mineralogy and Chemistry. Reviews Middle to Upper Cambrian platform carbonates: Implications for in Mineralogy. Mineralogical Society of America 11, 265-299. the evolution of Cambrian seawater 87Sr/86Sr. Geology 24, 917-920. Veizer, J., Buhl, D., Diener, A., Ebneth, S., Podlaha, O.G., Bruckschen, Nabelek, P.I. 1991: Stable isotope monitors. In Kerrick, D.M. (ed): P.,Jasper, T., Korte, C., Schaaf, M., Ala, D. & Azmy, K. 1997: Stron- Contact Metamorphism, Reviews in Mineralogy 26,Mineralogical tium isotope stratigraphy: potential resolution and event correla- Society of America, p. 395-435. tion. Palaeogeography, Palaeoclimatology, Palaeoecology 132, 65-77. Northrup, C.J. 1997: Timing, structural assembly, metamorphism, and Veizer, J., Ala, D., Azmy, K., Bruckschen, P., Buhl, D., Bruhn, F., Carden, cooling of Caledonian nappes in the Ofoten-Efjorden area, nor- G.A.F., Diener, A., Ebneth, S., Godderis, Y., Jasper, T., Korte, C., thern Norway: tectonic insights from U-Pb and 40Ar/39Ar geochro- Pawellek, F., Podlaha, O.G. & Strauss, H. 1999: 87Sr/86Sr, δ13C and nology. Journal of Geology 105, 565-582. δ18O evolution of Phanerozoic seawater. Chemical Geology 161, 59- Oliver, G.J.H. & Krogh, T.E. 1995: U-Pb zircon age of 469 ± 5 Ma for a 88. metatonalite from the Kjosen Unit of the Lyngen Magmatic Com- Wickham, S.M. & Peters, M.T. 1993: High δ13C Neoproterozoic carbo- plex northern Norway. Norges geologiske undersøkelse Bulletin 428, nate rocks in western North America. Geology 21, 165-168. 27-32. Roberts, D. & Gee, D. 1985: An introduction to the structure of the Scandinavian Caledonides. In Gee, D.G. & Sturt, B.A. (eds): The Caledonide Orogen – Scandinavia and Related Areas, 55-68. John Wiley & Sons Ltd., Chichester. Roberts, D., Heldal, T. & Melezhik, V. A. 2001: Tectonic structural fea- NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 231

Appendix 1. Analytical techniques.

Major and trace elements were analysed by X-ray fluorescence spectro- metry at the Geological Survey of Norway (NGU), Trondheim, using a Philips PW 1480 X-ray spectrometer. The precision (1σ) is typically around 2% of the major oxide present. Acid-soluble Fe, Ca, Mg and Mn were analysed by ICP-AES at NGU using a Thermo Jarrell Ash ICP 61 instrument. Detection limits for Fe, Mg, Ca and Mn are 5 ppm, 100 ppm, 200 ppm and 0.2 ppm, respectively. The total analytical uncer- tainty including element extraction (1σ) is ± 10% rel.

Oxygen and carbon isotope analyses of whole-rock marble samples were carried out at the Scottish Universities Environmental Research Centre, Glasgow, using the phosphoric acid method of McCrea (1950) as modified by Rosenbaum & Sheppard (1986) for operation at 100°C. Carbon and oxygen isotope ratios in carbonate constituents of the whole-rock samples were measured on a VG SIRA 10 mass spectrome- ter. Analyses were calibrated against NBS 19, and precision (1σ) for both isotope ratios is better than ± 0.2‰. Oxygen isotope data for dolomites were corrected using the fractionation factor 1.00913 recommended by Rosenbaum & Sheppard (1986). The δ13C data are reported in per mil (‰) relative to V-PDB and the δ18O data in ‰ relative to V-SMOW.

Rb-Sr analyses were carried out at the Institute of Precambrian Geo- logy and Geochronology of the Russian Academy of Sciences, St. Petersburg, as specified in Gorokhov et al. (1995). The Rb and Sr con- centrations were determined by isotope dilution. Sr concentrations obtained by isotope dilution are systematically 15% higher compared with those determined by ICP-AES at NGU. Rb isotopic composition was measured on a multi-collector MI 1320 mass spectrometer. Stron- tium isotope analyses were performed in static mode on a Finnigan MAT-261 mass spectrometer. All 87Sr/86Sr ratios were normalised to a 87Sr/86Sr of 0.1194 and measurements of the NIST SRM-987 run with σ every batch averaged 0.710256 ± 10 (2 mean, n=15). During the course of the study, the value obtained for the 86Sr/88Sr ratio of the U.S.G.S. σ EN-1 standard was measured at 0.709201 ± 8 (2 mean, n=5). 232 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Appendix 2. Chemical, carbon and oxygen isotope composition of marbles in the northern Ofotfjorden area.

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Narvik nappe complex Northern slope of Sørtuva Mountain Dark grey,banded, crystalline marble ED30 11.3 2.9 0.24 0.76 0.15 0.02 0.34 0.42 29.8 1090 72 1490 0.05 0.014 +6.0 21.5

Evenes coastal section Dark grey,banded, crystalline marble MP-55 2.05 0.48 0.24 0.09 0.05 n.d. n.d. 0.26 33.7 527 41 1230 0.034 0.008 +5.8 23.6

Steinsland marble Høgåskollen, coastal section Dark grey,banded, crystalline marble MP-93 5.46 1.36 0.28 0.33 0.08 n.d. n.d. 0.65 29.8 1880 247 3180 0.08 0.02 +1.8 17.6 MP-94 5.43 0.45 0.29 0.16 0.11 n.d. n.d. 2.93 27.9 264 35.8 1280 0.03 0.11 +5.7 20.8

Tjeldsundbrua-Evenskjer coastal section Dark grey,banded, crystalline marble EG20 - - - - 0.13 0.03 - 0.23 36.5 130 78 916 0.09 0.006 +4.8 27.0 EG21 - - - 0.005 0.13 0.03 - 0.21 36.4 70 53 726 0.07 0.006 +4.4 26.1 EG22 - - - 0.006 0.12 0.03 - 0.19 36.4 69 63 652 0.10 0.005 +3.3 28.8 EG24 4.5 0.15 - 0.011 0.09 0.03 0.17 1.84 33.0 312 44 1570 0.03 0.06 +4.0 29.0 EG25 3.2 0.17 0.13 0.017 0.12 0.03 0.21 0.85 34.6 237 50 1450 0.03 0.02 +4.0 20.5 EG26 0.13 - - 0.008 0.11 0.02 0.21 0.74 35.4 275 31 1530 0.02 0.02 +4.8 22.2 EG27 6.9 0.46 - 0.13 0.09 0.02 0.12 0.13 34.0 273 24 1370 0.018 0.004 +5.4 26.3 EG28 11.4 2.4 0.11 0.65 0.11 0.04 0.51 0.26 30.9 814 60 1090 0.06 0.009 +4.9 23.8 EG29 10.9 2.0 0.22 0.41 0.09 0.04 0.13 0.22 30.8 1070 89 972 0.09 0.007 +5.3 19.1 EG30 1.9 - - - 0.12 0.02 0.16 1.41 33.4 199 13 1320 0.010 0.04 +4.5 22.0 EG31 7.2 1.5 0.78 0.40 0.22 0.06 0.21 0.13 33.7 291 34 1500 0.02 0.004 +6.0 21.3 EG32 3.2 1.2 0.38 0.08 0.14 0.02 - 0.20 33.9 4780 356 1250 0.28 0.006 +2.9 17.9 EG33 0.3 0.14 - 0.02 0.15 0.02 0.10 0.14 35.8 160 21 1280 0.016 0.004 +6.4 24.1 EG34 4.0 1.3 0.14 0.30 0.13 0.04 0.27 0.15 34.1 119 46 1740 0.03 0.005 +5.0 22.7 EG35 4.8 1.4 0.21 0.27 0.16 0.04 0.28 0.18 33.9 878 34 1700 0.020 0.005 +6.0 16.8 EG36 1.2 0.18 - 0.05 0.13 0.02 - 0.19 35.8 178 40 591 0.07 0.005 +5.2 24.5 EG36a 1.6 0.16 - 0.05 0.14 0.03 - 0.22 35.5 324 109 707 0.15 0.006 +4.8 24.7 EG37 1.2 0.01 - - 0.12 0.02 0.14 0.41 35.2 286 27 1720 0.02 0.012 +5.0 20.8

Glefellet Dark grey,banded, crystalline marble Sand 1 2.8 0.59 0.22 0.09 0.11 0.12 0.11 0.10 37.1 n.d. 177 1833 0.10 0.003 +5.8 20.4 Sand 2 2.1 0.55 - 0.08 0.11 0.08 0.14 0.15 37.5 n.d. 62 1541 0.04 0.004 +6.0 19.8 Sand 3 4.3 1.12 0.17 0.22 0.08 0.12 0.16 0.10 36.3 n.d. 116 1651 0.07 0.003 +4.8 16.7 Sand 4 0.6 0.02 - - 0.10 0.07 0.19 0.57 37.9 n.d. 100 2046 0.05 0.02 +5.0 19.3 Sand 9 2.8 0.42 0.47 0.17 0.17 0.14 0.20 0.13 37.3 n.d. 54 2497 0.02 0.003 +7.0 21.9 Sand 11 6.0 0.92 - 0.16 0.14 0.04 0.25 0.20 35.7 n.d. 85 2419 0.04 0.006 +5.1 21.3 Sand 12 2.2 0.59 0.13 0.012 0.11 0.03 0.16 0.23 37.5 n.d. 62 1777 0.03 0.006 +5.0 21.5 Sand 13 7.2 1.8 0.69 0.11 0.05 0.11 0.18 0.13 34.7 n.d. 62 1617 0.04 0.004 +5.1 20.5

Ramstad thrust sheet from the western limb of the Ofoten Synform, the area north of Ofotfjorden Fjelldalsheia Pale grey and white, massive and thickly banded, coarsely crystalline, calcite marbles A98-12 1.0 0.09 - 0.13 0.08 - - 1.69 36.3 600 46 275 0.17 0.05 +0.6 22.4 A98-4 1.2 - - 0.03 0.21 - - 0.33 35.9 321 23 283 0.08 0.009 -0.6 21.9 NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 233

Appendix 2. (Continued)

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Fjelldalsheia Pale grey and white, massive and thickly banded, coarsely crystalline, calcite marbles A98-10 0.5 - - 0.04 0.10 - - 0.22 36.1 56 12 297 0.04 0.006 -0.1 23.6 A98-11 0.5 0.02 - 0.05 0.10 - - 0.26 35.5 95 12 325 0.04 0.007 -0.7 22.3 A98-13 0.7 - - 0.02 0.09 - - 0.33 31 42 24 233 0.10 0.010 -0.3 23.6 A98-14 1.0 0.02 - 0.09 0.08 - - 0.79 29.5 79 14 231 0.06 0.027 -0.4 23.7 A98-15 2.3 - - 0.03 0.08 - - 0.37 29.9 53 14 227 0.06 0.012 -0.9 23.2 A98-17 0.9 - - 0.05 0.08 - - 1.46 23.6 77 15 185 0.08 0.062 -0.5 22.7 A98-18 - - - - 0.09 - - 0.15 22.2 30 7 135 0.05 0.007 +1.5 22.5 A98-20 - - - - 0.10 - - 0.49 18.4 30 10 109 0.09 0.027 +1.7 24.2 B98-3 - - - 0.02 0.10 - - 0.59 28.9 407 31 246 0.13 0.021 -0.4 22.7 B98-13 - - - 0.01 0.09 - - 0.52 36.6 90 39 263 0.15 0.014 +0.6 22.9 B98-15 0.9 - - 0.06 0.08 - - 0.25 36.2 219 17 317 0.05 0.007 -0.6 21.5 B98-16 - - - - 0.10 - - 0.24 35.9 68 32 321 0.10 0.007 +0.9 18.0 B98-19 - - - - 0.08 - - 0.21 36.7 156 15 293 0.05 0.006 -0.3 22.8 B98-20 0.4 - - 0.02 0.09 - - 0.90 35.3 254 41 271 0.15 0.025 +0.3 22.6 B98-22 - - - - 0.11 - - 0.24 36.5 32 13 297 0.04 0.007 -1.0 23.1 C98-14 - - - - 0.09 - - 0.24 36.3 58 14 211 0.07 0.007 +1.1 24.8 ED1 - - - - 0.09 0.03 - 0.17 36.7 234 39 231 0.2 0.005 +0.1 22.8 ED2 4.1 0.15 - 0.02 0.08 0.02 - n.d. n.d. n.d. n.d. n.d. n.d. n.d. +0.2 23.4 ED3 0.5 - - 0.02 0.09 0.03 - 0.39 36.3 59 16 316 0.05 0.011 +0.0 23.2 ED4 0.2 0.02 - 0.03 0.09 0.03 - 0.84 35.7 109 15 222 0.07 0.02 +1.3 22.4

White, finely crystalline, dolomite marbles ED19 2.4 5.3 - 0.03 0.08 0.02 - 11.9 20.0 852 49 59.6 0.82 0.60 +3.2 22.4 ED20 3.5 0.06 - 0.04 0.12 0.03 - 10.6 20.9 1670 94 91.0 1.03 0.51 +2.6 20.4 ED23 0.2 0.03 - 0.04 0.05 0.02 - 12.7 20.1 843 89 41.6 2.1 0.63 +0.3 22.7 ED26 0.1 0.02 - - 0.05 0.03 - 12.6 20.1 1140 104 39.0 2.7 0.63 +0.6 22.4

Evenskjer-Evenes road profile Pale grey, thinly banded, calcite marbles MP-44 1.3 0.49 0.23 0.08 0.06 - - 1.50 33.0 2340 92 249 0.37 0.05 +1.5 20.5 MP-45 4.2 1.29 0.33 0.34 0.09 - - 3.96 27.5 2640 127 515 0.25 0.14 +0.3 20.4 MP-46 1.4 0.40 0.23 0.35 0.07 - - 2.36 31.9 886 47 293 0.16 0.07 +1.3 21.5 MP-47 - - 0.21 - 0.04 - - 0.39 36.5 214 24 159 0.15 0.01 +1.2 21.4

White, massive, finely crystalline, dolomite marbles MP-43 11.8 0.13 0.19 0.04 0.12 - - 8.6 20.1 2620 111 123 0.90 0.43 +2.5 21.0 MP-48 0.5 0.32 0.15 0.15 0.09 - - 12.1 21.1 1730 78 57.9 1.3 0.57 +1.2 21.9 MP-49 - - 0.14 0.03 0.09 - - 12.5 20.6 2610 160 47.9 3.3 0.61 -0.1 21.1

Evenes coastal section White, coarsely crystalline, calcite marbles MP-54 2.2 0.29 0.26 0.11 0.07 - - 0.25 33.1 317 177 3030 0.06 0.007 +1.6 20.5 MP-58 - 0.03 0.21 0.10 0.06 - - 4.02 30.6 613 60 183 0.33 0.13 +1.3 18.9 MP-59 1.7 - 0.23 0.04 0.04 - - 0.13 34.6 377 58 209 0.28 0.004 -0.4 20.0 MP-60 1.3 - 0.23 0.07 0.04 - - 0.17 34.9 561 51 239 0.21 0.005 -0.4 21.1 MP-61 6.0 1.36 0.23 0.77 0.07 - - 1.35 28.7 916 90 216 0.41 0.05 -0.8 20.2 MP-63 - 0.03 0.21 0.06 0.05 - - 1.40 34.3 349 40 220 0.18 0.04 -0.1 20.0 MP-65 - - 0.22 0.01 0.04 - - 0.17 36.6 229 23 180 0.13 0.005 +1.3 20.0 MP-68 - - 0.22 - 0.04 - - 0.23 36.4 37 10 220 0.05 0.006 +0.0 21.1 MP-69 0.5 0.08 0.22 0.11 0.06 - - 2.49 33.2 577 50 224 0.22 0.08 -1.0 21.8 MP-62 12.7 0.72 0.19 0.25 0.09 - - 8.3 18.0 7260 226 191 1.18 0.46 +3.9 18.8 MP-64 0.8 0.22 0.15 0.12 0.09 - - 11.7 20.7 1630 71 66.1 1.08 0.57 +0.9 19.7 234 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Appendix 2. (Continued)

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Ramstad thrust sheet from the eastern limb of the Ofoten Synform, west of Bjerkvik North of Herjangsfjorden Grey, thinly banded, finely crystalline, calcite marbles Bj1 2.2 0.11 - 0.12 0.08 0.021 - 0.44 38.7 n.d. 39 377 0.10 0.01 -1.1 20.2 Bj2 4.2 0.48 - 0.31 0.07 0.022 - 1.5 36.6 n.d. 54 367 0.15 0.04 -1.5 18.4 Bj3 1.2 0.08 - 0.11 0.09 0.020 - 0.25 39.2 n.d. 39 382 0.10 0.006 -1.2 19.9 Bj4 8.0 0.60 - 0.30 0.05 0.024 - 2.9 33.7 n.d. 54 424 0.13 0.09 -1.1 16.2 Bj5 1.3 0.14 - 0.18 0.10 0.023 - 4.1 35.4 n.d. 77 375 0.21 0.11 +2.2 21.2 Bj6 0.65 0.10 - 0.10 0.13 0.023 - 1.2 38.5 n.d. 231 319 0.72 0.03 +0.3 19.5 Bj7 20.7 0.12 - 0.10 0.02 0.028 - 1.0 31.2 n.d. 46 380 0.12 0.03 +0.3 20.0 Bj8 0.48 0.05 - 0.08 0.09 0.025 - 0.85 39.0 n.d. 39 248 0.16 0.02 +0.3 20.1

Evenestangen thrust sheet from the western limb of the Ofoten Synform Northern slope of Sørtuva Mountain Dark grey laminated and, banded, calcite marbles C98-2 1.47 - - 0.02 0.11 - - 1.28 34.9 96 8.5 399 0.02 0.04 +5.1 21.3 C98-5 2.0 - - - 0.13 - 0.15 0.85 35.2 106 27 675 0.04 0.02 +6.2 23.1 C98-9 3.08 - - - 0.1 - - 1.85 33.5 205 22 426 0.05 0.06 +4.6 20.4 A98-16 1.03 - - - 0.11 - - 1.48 27.7 106 11 623 0.02 0.053 +5.1 21.3 ED28 2.21 - - 0.05 0.2 0.01 0.13 1.7 34.0 244 34 775 0.04 0.05 +5.7 22.6 ED29 2.01 0.21 - 0.18 0.23 0.01 0.11 1.3 33.8 295 30 1490 0.02 0.04 +4.7 20.6

Variegated, calcite marbles ED5 3.7 0.8 - 0.60 0.21 0.01 - 0.47 33.8 1240 35 924 0.04 0.01 -8.5 20.7 ED6 9.5 2.0 - 0.77 0.23 0.12 - n.d. n.d. n.d. n.d. n.d. n.d. n.d. -7.1 18.6 ED21 2.0 0.4 - 0.28 0.17 0.01 - 0.17 34.4 962 61 1590 0.04 0.01 -9.9 14.2 ED25 4.7 0.8 - 0.29 0.25 0.01 - 0.44 33.1 1520 88 354 0.25 0.013 -8.2 19.4 ED27 6.2 1.5 0.2 0.70 0.19 0.02 - 0.58 31.9 1940 100 252 0.40 0.02 -7.9 21.0

Evenestangen Dark grey, laminated, calcite marbles Ev19 1.04 0.07 - 0.09 0.16 0.02 0.13 1.3 34.0 75 8.9 905 0.01 0.04 +5.8 21.7 Ev20 2.03 0.38 - 0.21 0.09 0.03 - 3.9 30.0 205 24 668 0.04 0.13 +3.8 21.7 Ev22 1.60 - - 0.01 0.27 0.02 - 1.6 33.2 61 19 624 0.03 0.05 +4.8 22.8 EVT 3 4.98 - - 0.03 0.09 0.04 - 2.6 31.7 182 21 494 0.04 0.08 +4.8 20.4 EVT 4 5.12 0.03 - 0.09 0.21 0.04 - 4.2 28.5 193 22 593 0.04 0.15 +4.0 19.9 EVT 6 0.38 - - 0.01 0.22 0.03 0.11 0.50 35.4 42 15 1140 0.013 0.014 +5.1 21.5 EVT 7 2.03 - - 0.09 0.16 0.04 0.21 3.0 31.8 57 16 603 0.03 0.09 +5.7 20.4 EVT 8 41.1 - - - 0.78 0.04 0.11 0.79 21.7 27 7.3 677 0.011 0.04 +5.6 21.4 EVT 14 - - - 0.004 0.19 0.02 - 0.71 35.6 20 11 834 0.013 0.02 +5.5 20.8 EVT 15 - - - - 0.46 0.04 0.13 0.28 36.1 19 12 912 0.013 0.008 +5.4 21.6

Variegated, calcite marbles EVT 9 3.0 0.3 - 0.19 0.11 0.04 - 0.50 35.0 1380 57 482 0.12 0.014 -7.8 20.9 EVT 10 6.9 1.1 - 0.47 0.11 0.05 - 0.49 33.1 1410 71 594 0.12 0.015 -8.3 20.5 EVT 11 3.4 0.4 - 0.22 0.18 0.15 - 0.44 34.3 355 25 5160 0.005 0.013 -8.0 21.5 Ev23 8.2 1.6 0.59 0.03 0.1 0.02 - 0.43 32.1 2950 198 232 0.85 0.013 -8.9 20.5 Ev24 1.4 0.1 - 0.02 0.11 0.02 - 0.17 35.6 282 47 1230 0.04 0.005 -8.8 22.8 Ev25 9.4 2.1 0.39 0.39 0.14 0.02 - 0.78 29.7 4140 130 548 0.24 0.03 -9.3 21.5 Ev26 5.8 1.1 0.14 0.21 0.13 0.02 - 0.65 32.6 3270 104 565 0.18 0.02 -9.2 21.2

White, coarsely crystalline, calcite marbles MP70 3.04 0.48 - 0.27 0.16 0.48 34.4 734 29.1 638 0.05 0.014 -6.3 19.7 Ev27 2.25 0.31 - 0.16 0.11 0.03 - 0.56 34.6 349 25.2 1490 0.02 0.02 -6.6 22.9 NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 235

Appendix 2. (Continued)

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Evenestangen White, coarsely crystalline, calcite marbles Ev28 2.48 0.32 - 0.17 0.1 0.02 - 0.54 33.7 301 22.5 3390 0.007 0.02 -6.3 23.2 EVT 12 - - - 0.04 0.12 0.03 - 0.28 35.5 65.6 26.6 614 0.04 0.008 -5.5 21.0 EVT 13 0.89 0.06 - 0.14 0.12 0.08 - 0.35 35.9 348 49.4 472 0.10 0.010 -5.5 22.5 EVT 16 2.13 0.32 - 0.29 0.13 0.07 - 0.39 35.5 210 28.3 571 0.05 0.011 -5.5 22.5 EVT 17 1.59 0.11 - 0.21 0.12 0.03 - 0.47 35.5 559 37.6 569 0.07 0.013 -5.9 21.8

Pale grey and grey dolomite marble and dolomitised calcite marbles EVT 2 0.63 0.03 - 0.004 0.06 0.04 0.10 12.5 21.0 261 61 76.3 0.80 0.60 +4.1 18.7 EVT 1 5.36 - - 0.01 0.05 0.02 0.12 6.93 26.0 322 67 130 0.52 0.27 +3.4 18.9 EVT 5 1.24 - - 0.07 0.03 0.04 - 6.5 26.9 345 52 248 0.21 0.24 +4.6 19.8 Ev21 2.64 0.21 - 0.11 0.07 0.02 - 6.4 27.1 163 24 292 0.08 0.24 +4.8 19.4

Soltun Dark grey, laminated, dolomitised calcite marbles ED9 3.37 - - 0.02 0.12 0.01 - 6.1 27.0 178 24 157 0.15 0.23 +3.4 18.9 ED16 4.81 0.07 - 0.06 0.17 0.01 0.11 4.0 28.7 292 28 292 0.09 0.14 +2.6 19.4 ED17 8.36 0.02 - 0.02 0.06 0.03 - 9.2 21.4 532 36 114 0.31 0.43 +1.2 22.3

Variegated, calcite marbles ED10 13.4 2.8 0.86 0.58 0.24 0.46 - 1.1 27.0 2270 119 273 0.44 0.04 -6.4 20.6 ED11 9.5 1.8 - 0.72 0.23 0.02 - 0.80 30.0 3090 97 258 0.37 0.03 -8.9 19.5 ED12 6.4 1.2 - 0.49 0.22 0.01 - 0.62 32.0 3280 81 370 0.22 0.02 -8.7 20.8 ED13 1.7 0.2 - 0.07 0.19 0.01 - 0.51 35.3 694 18 2630 0.007 0.014 -8.0 20.7 ED14 1.5 0.2 - 0.09 0.19 0.02 - 0.29 35.2 321 14 8740 0.002 0.008 -7.9 22.0 ED15 4.8 0.9 - 0.35 0.21 0.01 - 0.81 33.5 1630 44 2880 0.02 0.02 -7.7 21.4 ED18 7.4 1.6 0.24 0.47 0.26 0.23 - 0.67 31.1 1680 89 274 0.33 0.02 -6.8 21.0

Carbonate conglomerate, pink marble pebble EG40 3.9 0.9 - 0.29 0.13 - - 4.5 32.5 2415 146 243 0.62 0.14 +0.3 18.9

Northern slope of Kollan Mountain Dark grey, laminated and thinly banded, calcite marbles EG1 1.57 - - 0.05 0.10 0.02 0.13 2.3 32 61 13 543 0.02 0.07 +5.6 22.9 EG3 5.70 - - 0.04 0.08 0.03 0.17 3.0 29.9 86 15 327 0.05 0.10 +4.5 21.3 EG7 1.48 - - 0.04 0.14 0.02 0.12 1.6 32.6 40 7.5 347 0.02 0.05 +5.9 26.3 EG8 2.23 - - 0.03 0.10 0.02 0.11 4.1 30.0 77 11 160 0.07 0.14 +5.4 20.9 EG14 0.65 - - - 0.14 0.02 0.11 2.3 32.6 41 6.2 207 0.03 0.07 +6.0 28.1 EG16 6.99 - - 0.02 0.18 0.03 0.20 4.6 28.2 134 14 206 0.07 0.16 +4.3 20.4 EG17 11.7 0.18 - 0.10 0.11 0.02 0.19 3.3 27.8 220 28 372 0.08 0.12 +4.9 21.2 EG18 5.29 0.11 - 0.08 0.12 0.03 0.16 5.2 27.7 159 19 137 0.14 0.19 +4.5 20.4

Variegated, calcite marbles EG4 2.5 0.5 - 0.42 0.14 0.02 - 0.29 34.1 1240 36 2840 0.01 0.009 -8.6 21.4 EG6 4.4 1.0 - 0.62 0.13 0.02 - 0.46 33.0 2420 56 1790 0.03 0.014 -9.1 21.6 EG9 1.9 0.2 - 0.11 0.14 0.02 - 0.31 34.5 516 16 4310 0.004 0.009 -6.9 23.3 EG10 3.1 0.6 - 0.48 0.13 0.02 - 0.54 34.1 641 27 560 0.05 0.02 -7.0 22.4 EG11 3.6 0.9 - 0.53 0.13 0.02 - 0.50 33.5 2530 52 2130 0.02 0.015 -8.6 22.5

Høgåskollen, coastal section Dark grey,banded, medium crystalline, calcite marbles MP-95 3.40 1.06 0.22 0.58 0.07 n.d. n.d. 3.45 28.6 1940 111 209 0.53 0.12 +3.4 19.0 MP-96 0.52 0.14 0.15 0.08 0.10 12.5 20.0 1190 56.5 51.2 1.10 0.62 -0.9 21.3 MP-100 - - 0.15 0.02 0.10 12.5 20.3 743 59.6 57.7 1.03 0.62 -2.2 19.8 MP-101 1.01 0.22 0.26 0.07 0.05 n.d. n.d. 0.51 33.4 2470 118 316 0.37 0.02 +0.9 20.5 236 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Appendix 2. (Continued)

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Dark grey, finely crystalline, laminated dolomite marbles MP-102 2.66 - 0.23 0.03 0.10 n.d n.d. 2.48 30.6 609 42.7 188 0.23 0.08 +2.8 19.9

Høgåskollen, coastal section White, coarsely crystalline, calcite marbles MP-97 - - 0.23 0.03 0.04 n.d. n.d. 0.28 35.8 264 19.6 399 0.05 0.01 -5.1 21.2 MP-98 0.56 0.16 0.24 0.11 0.05 n.d. n.d. 0.40 34.4 504 30.0 706 0.04 0.01 -5.6 21.4 MP-99 0.79 0.20 0.22 0.13 0.05 n.d. n.d. 0.33 34.4 739 28.4 419 0.07 0.01 -5.0 19.7

Glefellet Dark grey,banded, medium-crystalline, calcite marbles Sand 5 - - - - 0.09 0.03 0.12 4.18 35.1 n.d. 23 267 0.09 0.12 +5.0 22.1 Sand 6 21.3 - - - 0.04 0.04 0.19 0.94 29.7 n.d. 31 268 0.11 0.03 +6.5 21.3 Sand 8 3.21 0.57 - 0.29 0.13 0.20 0.18 0.60 36.7 n.d. 69 347 0.20 0.02 +4.1 21.5

White, coarsely crystalline, calcite marbles Sand 10 1.30 - - 0.093 0.13 0.03 - 0.27 38.16 n.d. 31 789 0.04 0.007 -5.6 22.0

Boltåsen Dark grey, laminated, calcite marbles Ev18 1.01 - - - 0.12 0.02 - 0.61 35.0 47 18 598 0.03 0.02 +4.5 30.8

Variegated, calcite marbles Ev16 1.2 0.2 - 0.04 0.1 0.02 - 0.26 35.7 773 48 2210 0.02 0.007 -9.2 26.8 Ev17 5.6 1.1 - 0.30 0.14 0.02 - 0.41 32.6 1380 79 4610 0.02 0.013 -10.2 23.0 MP-51 1.0 0.3 0.28 0.05 0.05 n.d. n.d. 0.54 34.7 1840 159 431 0.37 0.02 -9.4 19.5

White, coarsely crystalline, calcite marbles MP-53 0.35 0.02 0.22 0.06 0.05 n.d. n.d. 0.38 35.5 536 60.5 522 0.12 0.011 -7.1 19.4

Evenskjer Dark grey, finely crystalline, laminated dolomite marbles Ev3 0.58 0.01 - 0.01 0.05 0.02 - 12.5 19.8 193 18 58.4 0.32 0.63 +5.5 21.5 Ev4 4.95 0.06 - 0.03 0.14 0.02 - 12.0 19.9 453 42 66.1 0.64 0.60 +2.4 27.5

Variegated, calcite marbles Ev5 5.4 1.0 - 0.40 0.14 0.02 - 0.76 33.4 1990 73 301 0.24 0.02 -7.9 20.8 Ev6 9.1 2.0 - 0.81 0.15 0.03 - 1.15 30.1 2630 87 273 0.32 0.04 -8.0 20.8

White, coarsely crystalline, calcite marbles Ev7 0.75 0.11 - 0.11 0.14 0.02 - 0.22 35.2 192 13.7 950 0.014 0.006 -7.2 21.1

Evenes coastal section Dark grey,crystalline, calcite marble MP-57 0.48 - 0.23 0.02 0.07 n.d. n.d. 1.99 33.3 183 42 482 0.09 0.06 +4.2 18.5 MP-66 - - 0.23 - 0.05 n.d. n.d. 0.58 36.2 57 37 441 0.08 0.02 +4.3 20.5 MP-67 0.79 0.10 0.23 0.03 0.06 n.d. n.d. 1.22 34.3 63 13 361 0.04 0.04 +5.3 21.4

Dark grey,medium crystalline, dolomite marbles MP-56 - - 0.15 - 0.11 n.d. n.d. 12.85 20.6 400 47 96.6 0.48 0.62 +3.4 24.5

Evenestangen thrust sheet from the eastern limb of the Ofoten Synform South of Bjerkvik Pale and dark grey, laminated and thinly banded, calcite marble EX36 5.2 0.06 - 0.02 0.38 - 0.27 2.29 35.1 n.d. 69 452 0.15 0.07 +2.6 19.0 NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 237

Appendix 2. (Continued)

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Pale and dark grey, laminated and thinly banded, calcite marble EX38 1.6 0.30 - 0.12 0.11 - - 0.37 38.0 n.d. 39 2418 0.02 0.02 -2.4 22.5 EX41 10.3 1.85 - 0.60 0.08 - - 2.39 31.6 n.d. 100 836 0.12 0.13 -2.8 20.0

South of Bjerkvik White, coarsely crystalline, calcite marble EX37 3.0 0.41 - 0.14 0.14 - - 0.55 37.4 n.d. 54 569 0.09 0.02 -5.9 21.7 EX40 6.7 0.86 - 0.27 0.11 - - 0.65 35.9 n.d. 162 463 0.35 0.03 -5.7 21.5

Dark grey, finely crystalline, banded, calcite marble

Dark grey, finely crystalline, banded, dolomitised, calcite marble EX39 27.3 1.47 0.27 0.23 0.21 - 0.42 7.97 17.5 n.d. 62 300 0.21 0.46 +0.6 19.0 EX42 22.1 2.20 0.24 0.47 0.18 - 0.61 8.30 18.4 n.d. 77 467 0.16 0.45 +1.2 18.9

Tangen schist sequence from the area north of Herjangsfjorden West of Bjerkvik Dark grey,banded, coarsely crystalline, calcite marbles Bj9 12.3 2.82 - 0.75 0.08 0.04 0.30 0.42 32.9 187 14.6 1097 0.013 0.013 +6.4 20.8 Bj10 0.67 0.20 - 0.055 0.11 0.02 0.16 0.20 37.0 156 19.9 1290 0.015 0.005 +6.0 21.6 Bj11 0.55 0.16 - 0.035 0.13 0.02 - 0.17 35.8 152 21.9 1510 0.015 0.005 +5.7 21.9 Bj12 2.1 - - - 0.08 0.02 0.12 0.51 35.2 164 14.2 1460 0.01 0.015 +5.8 23.9 Bj13 1.1 - - 0.012 0.10 0.03 0.20 0.51 35.6 177 16.7 1960 0.009 0.014 +5.5 21.8

Fuglevann Marble from the eastern limb of the Ofoten Synform Road section north of Herjangen Dark grey, thickly banded, coarsely crystalline, calcite marbles Bj14 1.1 0.15 - 0.03 0.25 0.05 0.12 0.38 35.5 43.7 22.1 1450 0.015 0.011 +4.4 24.9 Bj15 4.5 1.00 - 0.30 0.25 0.52 0.21 0.46 33.6 400 75.4 1360 0.06 0.014 +5.3 20.8 Bj16 15.4 2.26 0.32 0.58 0.11 0.38 0.21 3.06 25.8 2840 93.9 911 0.10 0.12 +6.3 23.2 Bj17 12.6 1.56 0.41 0.36 0.15 0.05 0.16 2.56 27.9 2250 78.9 1060 0.07 0.09 +6.3 21.7 Bj18 11.5 3.17 0.36 0.84 0.15 0.05 0.39 0.81 28.8 5260 114 1740 0.07 0.03 +5.7 22.5 Bj19 20.7 5.03 0.51 0.91 0.10 0.32 0.43 0.53 24.3 4340 170 1060 0.16 0.022 +5.5 19.2 Bj20 14.6 2.26 0.18 0.50 0.16 0.05 0.27 0.59 28.8 2210 77.1 1580 0.05 0.02 +4.7 22.0 Bj21 20.9 3.48 0.46 0.70 0.15 0.05 0.27 0.65 25.6 5600 151 1500 0.10 0.03 +5.3 22.1 Bj22 10.8 1.85 0.24 0.41 0.14 0.05 0.19 0.64 30.8 2620 89.1 1480 0.06 0.02 +5.1 22.1 Bj23 8.0 0.53 - 0.13 0.30 0.08 0.31 1.87 30.5 319 34.8 1010 0.03 0.06 +1.7 20.9 Bj24 4.0 0.30 - 0.08 0.27 0.06 0.18 0.34 34.8 532 130 2040 0.06 0.01 +3.2 17.9 Bj25 3.7 1.04 - 0.20 0.24 0.10 0.23 0.17 34.1 71.7 39.8 1470 0.03 0.005 +5.6 22.0 Bj26 2.2 0.25 - 0.05 0.30 0.07 0.31 0.39 34.9 105 18.3 1810 0.01 0.011 +4.1 22.1 Bj27 4.2 1.12 - 0.22 0.30 0.08 0.38 0.36 34.0 203 37.0 2250 0.016 0.011 +3.4 23.2 Bj28 12.6 1.81 0.12 0.27 0.46 0.07 0.61 0.42 29.7 1350 94.6 1920 0.05 0.014 +1.4 22.2 Bj28a 32.0 6.86 0.46 1.31 0.36 0.68 1.17 0.21 19.1 1100 119 1200 0.099 0.011 +0.3 23.6 Bj30 3.7 0.80 - 0.18 0.25 0.08 0.21 0.31 34.0 188 26.3 2420 0.011 0.009 +3.7 22.8 Bj31 4.3 0.90 - 0.14 0.29 0.07 0.29 0.22 34.0 1210 32.2 2600 0.012 0.007 +4.5 23.4 Bj32 5.1 1.12 0.12 0.22 0.22 0.08 0.34 0.36 33.2 725 39.3 2220 0.018 0.011 +4.1 23.9 Bj33 0.2 0.06 - 0.01 0.25 0.06 0.23 0.73 35.7 153 22.7 1580 0.014 0.020 +2.7 17.5 Bj34 3.9 0.48 - 0.11 0.24 0.06 0.26 0.31 33.9 179 18.2 1840 0.01 0.009 +4.0 22.1 Bj35 6.1 1.29 0.11 0.21 0.21 0.06 0.43 0.22 32.6 928 38.5 2370 0.016 0.007 +4.7 24.7 Bj36 4.0 0.91 - 0.24 0.23 0.10 0.24 0.16 33.8 153 47.8 2160 0.022 0.005 +6.0 25.8 Bj37 4.0 0.82 0.18 0.17 0.24 0.07 0.28 0.32 34.3 355 33.7 1970 0.017 0.009 +3.7 24.6 238 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Appendix 2. (Continued)

♥ ♥ ♥ ♥ ♥ δ13 δ18 Sample SiO2 Al2O3 Na2OK2OP2O5 STOCMg Ca Fe Mn Sr Mn/Sr Mg/Ca C O #wt %ppm ‰

Pale grey, finely crystalline, dolomite marble Bj29 0.9 - - - 0.07 0.06 - 12.1 21.2 538 34.4 387 0.09 0.57 +4.1 20.6

Coastal section south of Botn Dark grey, thickly banded, coarsely crystalline, calcite marbles MP-87 5.50 1.32 0.39 0.32 0.10 n.d. n.d. 0.49 28.0 1440 116 1390 0.08 0.02 +5.5 20.9 MP-88 1.57 0.18 0.24 0.09 0.07 n.d. n.d. 1.08 32.6 369 55.8 1150 0.05 0.03 +0.1 20.3 MP-89 6.12 2.11 0.32 0.47 0.08 n.d. n.d. 0.57 28.7 4240 217 1370 0.16 0.02 +4.3 10.7 MP-91 3.04 0.80 0.33 0.18 0.08 n.d. n.d. 0.33 31.4 659 84.7 1750 0.05 0.01 +5.9 21.0 MP-92 4.29 0.51 0.26 0.20 0.10 n.d. n.d. 1.63 29.1 355 146 1030 0.14 0.06 +5.4 17.9

Hekkelstrand Marble Western Liland area MP-75 22.1 - 0.23 0.04 0.23 n.d. n.d. 2.44 17.5 394 25.7 950 0.03 0.14 +3.1 22.2

Eastern Bogen area MP-81 0.35 - 0.23 0.02 0.07 n.d. n.d. 0.66 34.2 146 38.7 761 0.05 0.02 +2.5 21.6 MP-82 29.9 - 0.17 - 0.08 n.d. n.d. 5.50 15.3 1320 113 187 0.60 0.36 +2.1 18.4 MP-83 5.45 1.21 0.28 0.24 0.07 n.d. n.d. 1.44 28.9 1980 157 1080 0.15 0.05 +3.7 13.1 MP-84 7.56 0.61 0.27 0.15 0.10 n.d. n.d. 1.13 28.0 1830 368 647 0.57 0.04 +1.7 12.7 MP-85 4.05 0.44 0.25 0.12 0.11 n.d. n.d. 1.11 30.1 905 164 614 0.27 0.04 +2.2 14.4

Liland marble Bogen Dark grey, thickly banded, coarsely crystalline, calcite marbles MP-79 - - 0.22 - 0.05 - - 0.39 36.1 179 184 847 0.22 0.011 +5.0 18.5 MP-80 5.8 0.45 0.29 0.10 0.10 - - 0.50 30.7 267 69.9 1140 0.06 0.02 +4.0 20.6 Bog1 0.3 - - - 0.27 0.02 0.15 0.45 36.5 256 15.6 916 0.02 0.012 +3.8 16.9 Bog2 5.4 0.93 - 0.18 0.18 0.04 0.25 0.37 34.7 777 82.5 1800 0.05 0.011 +3.0 15.7 Bog3 12.0 0.33 - 0.06 0.19 0.02 0.14 0.16 33.3 368 59.6 1550 0.04 0.005 +5.3 23.2 Bog4 2.8 0.04 - 0.01 0.20 0.02 0.11 0.18 36.0 41.9 18.0 1700 0.01 0.005 +6.5 27.7 Bog5 6.1 0.39 - 0.07 0.22 0.03 0.12 0.33 34.9 519 48.2 1810 0.03 0.009 +3.9 19.7 Bog6 1.1 - 0.26 0.02 0.18 0.02 - 2.42 34.0 48.3 32.8 431 0.08 0.07 +2.1 19.4 Bog7 3.5 0.52 0.14 0.10 0.22 0.04 0.29 0.57 34.1 388 90.1 1540 0.06 0.02 +3.6 14.6 Bog8 2.8 0.17 - 0.02 0.35 0.02 0.30 1.21 34.1 100 26.1 712 0.04 0.04 +2.6 16.4

North of Bogen Dark grey, thickly banded, coarsely crystalline, calcite marbles MP-76 - - 0.23 0.01 0.05 n.d. n.d. 0.81 35.3 55.6 14.9 949 0.016 0.02 +4.8 21.8

White dolomite marble MP-77 - - 0.17 - 0.09 n.d. n.d. 12.36 20.8 1810 94.0 104 0.9 0.59 +3.9 24.1

West of Liland Calcite marble MP-73 6.80 0.78 0.28 0.26 0.12 n.d. n.d. 1.69 27.0 931 196 696 0.28 0.06 +2.6 16.7 MP-74 1.17 0.19 0.26 0.05 0.08 n.d. n.d. 1.76 32.8 538 134 1450 0.09 0.05 +3.2 22.4

‘Dashes’ – below detection limits: 0.1% for Na2O and TOC; 0.01% for SiO2,Al2O3,P2O5 and S; 0.003 for K2O. ‘n.d.’ – not determined. Mg♥,Ca♥,Fe♥,Mn♥ and Sr♥ - Mg, Ca, Fe, Mn, and Sr contents in acid-soluble constituents. NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 239

Appendix 3. Rb, Sr contents, elemental and strontium isotope ratios of acid-soluble constituents from marbles in the northern Ofotfjorden area.

Sample IR Minerals in Rb♥ Sr♥ Fe Mn Mn/Sr Mg/Ca 87Rb/86Sr 87Rb/86Sr 87Rb/86Sr #% IR ppm measured initial

Narvik nappe complex Northern slope of the Sørtuva Mountain Dark grey,banded, crystalline marble ED30 16.1 Ms, Qu, Fsp 1.4 1916 1090 72 0.037 0.014 0.0021 0.70735 0.70735

Evenes coastal section Dark grey,banded, crystalline marble MP-55 8.0 n.d. 0.13 1622 527 41 0.026 0.008 0.0002 0.70729 0.70729

Steinsland thrust sheet Tjeldsundbrua-Evenskjer coastal section Dark grey,banded, crystalline marble EG24 4.5 Qu, Fsp 0.17 1792 312 44 0.02 0.06 0.0003 0.70677 0.70677 EG25 3.0 Qu, Fsp, Ms 0.11 1636 237 50 0.03 0.02 0.0002 0.70699 0.70699 EG26 0.6 n.d. 0.08 1726 275 31 0.02 0.02 0.0001 0.70687 0.70687 EG27 7.0 Qu, Fsp 0.07 1623 273 24 0.015 0.004 0.0001 0.70696 0.70696 EG28 13.8 Ms, Qu, Fsp 0.38 1407 814 60 0.04 0.009 0.0008 0.70707 0.70706 EG30 2.2 Qu, Tlc, Ms 0.09 1456 199 13 0.009 0.04 0.0002 0.70702 0.70702 EG31 6.1 Ms, Qu, Fsp 0.11 1666 291 34 0.02 0.004 0.0002 0.70712 0.70711 EG33 1.0 Qu, Ms, Fsp 0.05 1388 160 21 0.015 0.004 0.0001 0.70686 0.70686 EG34 4.4 Ms, Qu, Fsp 0.17 1950 119 46 0.02 0.005 0.0002 0.70697 0.70697 EG35 6.7 Ms, Qu, Fsp 0.28 1934 878 34 0.02 0.005 0.0004 0.70694 0.70693 EG37 0.7 n.d. 0.02 1892 286 27 0.014 0.012 0.0001 0.70701 0.70700

Glefellet Dark grey,banded, crystalline marble Sand 2 3.8 Ms, Qu, Fsp 0.11 1590 n.d. 61 0.039 0.004 0.0002 0.70697 0.70697 Sand 4 1.6 Qu, Fsp 0.05 2082 n.d. 99 0.048 0.015 0.0001 0.70679 0.70679 Sand 9 4.5 Ms, Qu 0.17 2592 n.d. 54 0.021 0.003 0.0002 0.70710 0.70710 Sand 11 7.3 Ms, Qu, Fsp 0.20 2445 n.d. 85 0.035 0.006 0.0002 0.70725 0.70725 Sand 12 3.3 Ms, Qu, Fsp 0.05 1845 n.d. 64 0.033 0.006 0.0001 0.70756 0.70756 Sand 13 8.1 Fsp, Ms, Qu 0.11 1615 n.d. 58 0.038 0.004 0.0002 0.70713 0.70713

Ramstad thrust sheet from the western limb of the Ofoten Synform Fjelldalsheia Pale grey and white, massive and thickly banded, coarsely crystalline, calcite marbles A98-4 1.1 n.d. 0.06 318 321 23 0.07 0.009 0.0006 0.70948 0.70948 A98-10 1.2 Ms, Qu, Fsp 0.25 338 56 12 0.04 0.006 0.0022 0.70925 0.70923 A98-11 1.2 Ms, Qu 0.08 368 95 12 0.03 0.007 0.0007 0.70929 0.70929 A98-13 0.9 Ms, Qu, Fsp 0.01 280 24 233 0.10 0.01 0.0001 0.70940 0.70940 A98-14 2.1 Ms, Qu 0.20 313 14 231 0.06 0.03 0.0019 0.70931 0.70930 A98-15 1.9 Ms, Qu 0.02 331 14 227 0.06 0.012 0.0001 0.70935 0.70935 A98-17 1.3 Ms, Qu 0.03 322 15 185 0.08 0.06 0.0003 0.70928 0.70928 A98-18 0.3 n.d. 0.02 250 7.0 135 0.05 0.007 0.0002 0.70922 0.70922 A98-20 0.4 Ms, Qu 0.05 268 30 10 0.09 0.03 0.0005 0.70920 0.70920 B98-3 15.5 Qu, MS 0.20 305 407 31 0.10 0.02 0.0019 0.70927 0.70926 B98-12 0.5 Ms, Qu 0.02 214 158 41 0.19 0.05 0.0002 0.70943 0.70943 B98-13 0.5 Ms, Qu 0.13 268 90 39 0.15 0.014 0.0014 0.70930 0.70929 B98-15 0.7 Ms, Qu, Fsp 0.10 323 219 17 0.05 0.007 0.0009 0.70931 0.70931 B98-16 1.4 n.d. 0.06 335 68 32 0.10 0.007 0.0005 0.70969 0.70969 B98-19 0.8 Ms, Qu 0.06 291 156 15 0.05 0.006 0.0006 0.70946 0.70946 240 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Appendix 3. (Continued)

Sample IR Minerals in Rb♥ Sr♥ Fe Mn Mn/Sr Mg/Ca 87Rb/86Sr 87Rb/86Sr 87Rb/86Sr #% IR ppm measured initial

Pale grey and white, massive and thickly banded, coarsely crystalline, calcite marbles B98-20 0.7 Ms, Qu 0.27 285 254 41 0.14 0.025 0.0028 0.70938 0.70936 B98-22 0.1 Ms, Qu, Fsp 0.11 293 32 13 0.04 0.006 0.0011 0.70923 0.70922 C98-14 0.2 Qu 0.10 220 58 14 0.06 0.006 0.0014 0.70938 0.70937 ED1 0.1 n.d. 0.02 238 234 39 0.16 0.005 0.0003 0.70924 0.70924 ED3 0.4 n.d. 0.04 334 58.5 15.5 0.05 0.01 0.0004 0.70926 0.70926 ED4 0.2 n.d. 0.05 224 109 14.8 0.07 0.02 0.0006 0.70927 0.70927

Ramstad thrust sheet from the eastern limb of the Ofoten Synform, west of Bjerkvik North of Herjangsfjorden Grey, thinly banded, finely crystalline, calcite marbles Bj3 1.4 n.d. 0.03 388 n.d. 39 0.10 0.006 0.0001 0.70932 0.70931 Bj8 0.8 n.d. 0.14 257 n.d. 39 0.16 0.02 0.0002 0.70976 0.70974

Evenestangen thrust sheet from the western limb of the Ofoten Synform Northern slope of Sørtuva Mountain Dark grey, laminated and thinly banded, calcite marbles ED24 0.4 0.08 778 176 14 0.02 0.011 0.0003 0.70887 0.70887 ED28 1.2 Ms, Qu 0.20 877 244 34 0.04 0.05 0.0007 0.70837 0.70837 ED29 3.2 Ms, Qu 0.29 1760 295 30 0.02 0.04 0.0005 0.70827 0.70827 C98-2 1.8 Ms, Qu, Fsp 0.12 423 96 8.5 0.02 0.04 0.0008 0.70840 0.70839 C98-5 1.7 Qu, Fsp 0.14 697 106 27 0.04 0.02 0.0006 0.70823 0.70823 C98-9 1.6 Qu 0.003 440 205 22 0.05 0.06 0.0001 0.70843 0.70843

Variegated, banded, coarsely crystalline calcite marbles ED13 1.2 Ms, Qu 0.13 2876 694 18 0.006 0.014 0.0002 0.70863 0.70863 ED14 1.3 Ms, Qu 0.14 8818 321 14 0.002 0.008 0.0001 0.70859 0.70859 ED15 5.1 Ms, Qu 0.12 3388 1630 43 0.013 0.024 0.0001 0.70864 0.70864 ED21 2.8 Qu, Fsp 0.09 1862 962 61 0.033 0.005 0.0001 0.70861 0.70861 ED25 2.0 Qu, Ms 0.08 482 176 14 0.113 0.013 0.0005 0.71004 0.71004

Evenestangen Dark grey, laminated and thinly banded, calcite marbles Ev19 1.9 n.d. 0.25 1200 74 8.9 0.007 0.04 0.0006 0.70826 0.70826 Ev20 3.5 n.d. 0.09 906 205 24 0.03 0.13 0.0003 0.70831 0.70831 Ev22 1.8 n.d. 0.09 805 61 19 0.02 0.05 0.0003 0.70826 0.70826 EVT 6 0.1 n.d. 0.10 1310 42 15 0.011 0.01 0.0002 0.70826 0.70826 EVT 7 0.6 Qu, Ms 0.08 765 57 16 0.02 0.09 0.0003 0.70826 0.70826 EVT 14 8.0 Ms, Qu 0.09 1031 20 11 0.011 0.02 0.0003 0.70823 0.70823 EVT 15 0.2 Ms, Qu 0.05 1004 19 12 0.012 0.01 0.0001 0.70821 0.70821

Variegated,banded, coarsely crystalline calcite marbles EVT 11 4.3 Ms, Qu 0.06 6282 355 25 0.004 0.013 0.0001 0.70855 0.70855 Ev24 1.2 n.d. 0.17 1578 282 47 0.03 0.005 0.0003 0.70842 0.70842

White, coarsely crystalline, banded, calcite marbles Ev27 2.5 n.d. 0.068 1918 349 25 0.013 0.016 0.0001 0.70872 0.70872 Ev28 2.9 n.d. 0.094 4315 301 22 0.005 0.016 0.0001 0.70870 0.70870 EVT 12 0.1 n.d. 0.06 725 66 27 0.04 0.008 0.0003 0.70880 0.70880 EVT 16 2.3 Qu, Ms, Fsp 0.31 776 210 28 0.02 0.011 0.0012 0.70884 0.70884 EVT 17 2.2 Qu, Ms, Fsp 0.08 784 559 38 0.00 0.013 0.0003 0.70889 0.70889 NORWEGIAN JOURNAL OF GEOLOGY Isotope chemostratigraphy and detailed mapping of high-grade marble sequences 241

Appendix 3. (Continued)

Sample IR Minerals in Rb♥ Sr♥ Fe Mn Mn/Sr Mg/Ca 87Rb/86Sr 87Rb/86Sr 87Rb/86Sr #% IR ppm measured initial

Northern slope of Kollan Mountain Dark grey, laminated and thinly banded, calcite marbles EG7 1.9 Qu, Ms 0.09 466 40 7.5 0.02 0.05 0.0006 0.70836 0.70836 EG14 Ms, Gr 0.13 273 41 6.2 0.02 0.07 0.0014 0.70830 0.70829

Variegated, banded, coarsely crystalline calcite marbles EG4 1.9 Qu, Fsp 0.13 3638 1240 36 0.01 0.009 0.0001 0.70828 0.70828 EG6 4.9 Ms, Qu, Fsp 0.44 2321 2420 56 0.024 0.014 0.0006 0.70836 0.70836 EG9 1.2 Qu, Ms 0.06 5252 516 16 0.003 0.009 0.0001 0.70869 0.70869 EG11 3.6 Qu, Ms, Fsp 0.26 2475 2530 52 0.021 0.015 0.0003 0.70827 0.70827

Evenes coastal section Dark grey, laminated and thinly banded, calcite marbles MP-57 n.d. 0.09 396 183 42 0.11 0.06 0.0007 0.70860 0.70860 MP-66 n.d. 0.03 633 57 36 0.06 0.02 0.0001 0.70824 0.70824

Boltåsen Variegated, banded, coarsely crystalline calcite marbles Ev16 1.1 Ms, Qu, Fsp 0.21 2489 773 48 0.02 0.007 0.0002 0.70830 0.70830 Ev17 6.3 Ms, Qu, Fsp 1.37 5530 1380 79 0.014 0.013 0.0004 0.70824 0.70824

Evenestangen thrust sheet from the eastern limb of the Ofoten Synform South of Bjerkvik Dark grey, laminated and thinly banded, calcite marbles EX38 n.d. 0.09 2501 n.d. 39 0.02 0.02 0.0001 0.70873 0.70873

Tangen schist sequence from the area north of Herjangsfjorden West of Bjerkvik Dark grey, thickly banded, coarsely crystalline, calcite marbles Bj10 1.3 n.d. 0.056 1684 156 19.9 0.012 0.005 0.0016 0.70737 0.70737 Bj11 1.1 n.d. 0.22 1639 152 21.9 0.013 0.005 0.0001 0.70738 0.70738 Bj12 2.1 n.d. 0.13 1690 164 14.2 0.008 0.015 0.0004 0.70708 0.70708 Bj13 1.4 n.d. 0.19 2125 177 16.7 0.008 0.014 0.0003 0.70727 0.70727

Fuglevann Marble from the eastern limb of the Ofoten Synform Road section north of Herjangen Dark grey,medium-crystalline, thickly banded calcite marble Bj14 1.7 n.d. 0.25 1577 43.7 22.1 0.015 0.011 0.003 0.70669 0.70668 Bj15 6.5 Ms, Qu, Fsp 0.91 1577 400 75.4 0.06 0.014 0.0005 0.70695 0.70693 Bj18 17.6 Ms, Qu, Chl, Fsp 8.6 2256 5260 114 0.05 0.03 0.0112 0.70823 0.70813 Bj20 17.1 Ms, Qu, Chl, Fsp 0.53 2062 2210 77.1 0.05 0.02 0.0007 0.70753 0.70753 Bj25 6.3 Ms, Qu, Chl, Fsp 0.21 1766 71.7 39.8 0.03 0.005 0.0003 0.70662 0.70661 Bj26 2.9 Ms, Chl, Qu 0.41 2058 105 18.3 0.01 0.011 0.0006 0.70646 0.70646 Bj27 6.0 Ms, Qu, Fsp 0.22 2640 203 37.0 0.016 0.011 0.0002 0.70640 0.70640 Bj30 5.6 Ms, Qu, Fsp 0.16 2917 188 26.3 0.011 0.009 0.0002 0.70681 0.70680 Bj31 5.9 Ms, Qu, Chl, Fsp 0.23 3141 1210 32.2 0.012 0.007 0.0002 0.70657 0.70657 Bj32 6.7 Ms, Qu, Fsp 0.30 2787 725 39.3 0.018 0.011 0.0003 0.70674 0.70674 Bj33 0.9 Ms, Chl, Qu, Fsp 0.11 1773 153 22.7 0.014 0.020 0.0002 0.70667 0.70667 Bj34 5.0 Ms, Qu, Chl, Fsp 0.30 2249 179 18.2 0.01 0.009 0.0004 0.70674 0.70673 Bj35 8.9 Ms, Chl, Qu, Fsp 0.35 2939 928 38.5 0.013 0.007 0.0003 0.70666 0.70666 Bj36 6.3 Ms, Qu, Fsp 0.24 2693 153 47.8 0.022 0.005 0.0003 0.70646 0.70646 242 NORWEGIAN JOURNAL OF GEOLOGY V. A. Melezhik et al.

Appendix 3. (Continued)

Sample IR Minerals in Rb♥ Sr♥ Fe Mn Mn/Sr Mg/Ca 87Rb/86Sr 87Rb/86Sr 87Rb/86Sr #% IR ppm measured initial

Dark grey,medium-crystalline, thickly banded calcite marble Bj37 5.7 Ms, Qu, Fsp 0.12 2367 355 33.7 0.017 0.009 0.0002 0.70679 0.70679

Liland marble Bogen Dark grey, thickly banded, coarsely crystalline, calcite marbles MP-79 2.2 n.d. 0.07 911 179 184 0.20 0.011 0.0002 0.70694 0.70697 MP-80 n.d. n.d. 0.59 1559 267 69.9 0.04 0.02 0.0011 0.70676 0.70675 Bog1 0.7 n.d. 0.04 1017 256 15.6 0.02 0.012 0.0001 0.70685 0.70685 Bog2 7 Ms, Qu, Fsp 0.18 2099 777 82.5 0.04 0.011 0.0002 0.70714 0.70713 Bog3 11.6 Qu, Ms, Fsp 0.08 1955 368 59.6 0.03 0.005 0.0001 0.70679 0.70679 Bog4 3.3 Qu 0.07 1930 41.9 18.0 0.009 0.005 0.0001 0.70689 0.70688 Bog5 5.7 Qu, Ms, Fsp 0.1 2075 519 48.2 0.02 0.009 0.0001 0.70664 0.70665

North of Bogen Dark grey, thickly banded, coarsely crystalline, calcite marbles MP-76 0.5 n.d. 0.11 1188 55.6 14.9 0.013 0.02 0.0001 0.70656 0.70655

IR – insoluble residue. ‘n.d.' - not determined. Rb♥,Sr♥ - Rb and Sr contents were determined by standard isotope dilution and solid-source mass spectrometry. Abbreviations used: Chl – chlorite, Fsp – feldspar, Grt – garnet, Ms – muscovite, Qtu – quartz, Tlc - talc.