Geological Survey of Finland 2019

Isotope results from Lapland-Kola province in Finland

Hannu Huhma

GTK Open File Research Report 37/2019

GEOLOGICAL SURVEY OF FINLAND

Open File Research Report 37/2019

Hannu Huhma

Isotope results from Lapland-Kola province in Finland

Unless otherwise indicated, the figures have been prepared by the author of the publication.

Front cover: Sm-Nd isotopic evidence for the origin of crust in Lapland-Kola province, Finland.

Layout: Elvi Turtiainen Oy

Espoo 2019 Huhma, H. 2019. Isotope results from Lapland-Kola province in Finland. Geological Survey of Finland, Open file research report 37/2019, 44 pages, 52 figures, 1 table and 7 appendices.

Abundant isotopic data have been obtained from the Inari-Utsjoki area since the 1970’s. Many older results have recently been confirmed by U-Pb spot analyses. This paper reports on the abundant isotopic data now available on the Lapland-Kola Province in Finland. The U-Pb data on zircon include old U-Pb TIMS analyses from nearly 70 samples, together with more recent ICP-MS spot analyses on 20 samples. The old Pb-Pb TIMS data are presented from ca. 50 whole rocks and 30 K-feldspar separates. The previously unpublished Sm-Nd data produced at GTK consist of ca. 60 analyses. These data together with the results from the published papers provide the basis for understanding the geo- logical evolution of the Lapland-Kola Province. The main results include: -Archean gneisses occur in the Inarijärvi complex and Kevo window. Based on Pb-Pb isotope data from whole rocks and K-felspar and U-Pb ages on titanite the Archean rocks show strong 1.9 Ga metamorphic effects. -2.5 Ga rocks occur in two belts, in the Vuotso complex S-SW of granulites continuing further south to the Koitelainen area, and in the western border zone of the Archaean Inarijärvi complex. -Lapland-Kola Province east of granulites contains significant amount of 1.94-1.91 Ga juvenile crust with arc affinities. -Lapland granulite belt is characterised by migmatitic metasediments, 1.91-1.93 Ga enderbites and 1.904 Ga appinites. The metasediments were derived from 1.94-2.9 Ga sources and contain 1.91 Ga monazites and slightly younger metamorphic zircon con- current with the closure of the Sm-Nd system in garnet. The appinites are undeformed and set the lower age limit to the deformation of the granulite belt.

Appendices are available at: http://tupa.gtk.fi/raportti/aineistotallenne/37_2019.zip

Keywords: Finland, Lapland-Kola Province, juvenile crust, absolute age, U-Pb, Sm-Nd, Pb-Pb

Hannu Huhma Geological Survey of Finland P.O. Box 96 FI-02151 Espoo, Finland

E-mail: [email protected]

2 CONTENTS

1 INTRODUCTION...... 4

2 ANALYTICAL METHODS...... 4

3 GEOLOGICAL SETTING...... 4

4 PREVIOUS RESULTS OBTAINED USING HOME-MADE TIMS...... 5

5 U-PB RESULTS FROM ARCHAEAN INARIJÄRVI COMPLEX...... 6

6 U-PB RESULTS FROM PALEOPROTEROZOIC ROCKS: SILISJOKI & LUOSSAVARRI SUITES AND KAAMANEN COMPLEX...... 12

7 U-PB RESULTS FROM LAPLAND GRANULITE COMPLEX ENDERBITES, PARAGNEISSES AND DYKES...... 20

8 U-PB RESULTS FROM VASKOJOKI ANORTHOSITE AND VUOTSO COMPLEX...... 28

9 SM-ND RESULTS...... 34

10 PB-PB RESULTS...... 35

11 CONCLUDING REMARKS...... 37

ACKNOWLEDGEMENTS...... 39

REFERENCES...... 39

3 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

1 INTRODUCTION

Our understanding of the geological evolution of Lapland-Kola province have also been published by the Lapland-Kola Province in Finland was largely Bernard-Griffiths et al. (1984), Barbey et al. (1984), based on the comprehensive isotopic studies (U-Pb, Daly et al. (2001, 2006), Tuisku & Huhma (2006), Pb-Pb and Rb-Sr) performed by GTK in the early Tuisku et al. (2012), and most recently by Lahtinen 1970s. The main results were reported by Meriläinen & Huhma (2019). (1976), but no isotopic data were included in the The aim of this paper is to report on the avail- paper. Recent studies using U-Pb spot analyses able U-Pb, Sm-Nd and Pb-Pb data on the Lapland- on zircon have largely confirmed the old findings Kola province together with the main implications but together with Sm-Nd results also introduced of these reported results. new views on the topic. Relevant results from the

2 ANALYTICAL METHODS

The oldest U-Pb analyses in this report are from ICPMS analyses follow those in Huhma et al. (2012a, the 1960s, when mineral decomposition was under- 2012b, 2018), who also report procedures used for taken using the borax fusion method (Kouvo 1958). TIMS U-Pb and Sm-Nd analyses. The images of zir- Since the early 1970s, the procedure described by con analysed by laser ICPMS are shown in the data Krogh (1973) was adopted for multi-grain U-Pb tables to the right of the analytical results. Plotting analyses. The bulk of the old TIMS U-Pb analy- of the isotopic data and age calculations was per- ses in this paper were conducted by Dr. O. Kouvo formed using the Isoplot/Ex 3 program (Ludwig (unpublished reports). The methods used for laser 2003).

3 GEOLOGICAL SETTING

In Finland the Lapland–Kola Province covers the granulite complex and Kaamanen complex corre- northernmost part of the country. In the bedrock spond to the Lapland Granulite Belt (Fig. 1, Nironen map of Finland (Korsman et al. 1997), the area et al. 2016, Luukas et al. 2017). consisted of the Inari Complex and the Lapland The western boundary zone between the Lapland Granulite Belt. In the recent Finstrati compila- granulite complex and the Central Lapland area has tion the Archaean Inarijärvi complex and the been called the Tanaelv belt or, in the recent geo- Paleoproterozoic Silisjoki and Luossavarri suites logical map, the Vuotso complex (Luukas et al 2017). correspond to the Inari Complex while the Lapland

4 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

Fig. 1. The main lithodemic units of the Lapland-Kola Province according to Finstrati (Luukas et al. 2017).

4 PREVIOUS RESULTS OBTAINED USING HOME-MADE TIMS

The results obtained 40 years ago by Kouvo using – In the Lapland granulite belt meta-igneous rocks U-Pb on zircon, titanite and monazite include: have zircon ages of 1.91-1.93 Ga, whereas meta- – The Archaean Inari gneisses have zircon age sedimentary rocks provided heterogeneous zir- estimates 2.5-2.7 Ga, whereas titanites in these con populations with Pb/Pb ages of 2.0-2.15 Ga; samples are ca. 1.9 Ga. This is exceptional within monazites are ca. 1.91 Ga. the Archaean granitoids in Finland and sug- The Pb-Pb data on whole rocks and K-feldspar gests a strong 1.9 Ga thermal overprinting on suggested that: the Archaean crust NE of the granulite belt. In – The whole rock Pb-Pb age on the Archaean contrast, titanite in an Archaean rock on the gneisses is ca. 2.6 Ga, whereas K-feldspars in southern side of the granulite belt is Archaean. these rocks register Paleoproterozoic Pb isotopic – Quartz dioritic gneisses in Utsjoki, east of the compositions. granulite belt (Kuorboaivi belt in Meriläinen – The whole rock K-feldspar age estimate for the 1976) provide zircon age estimates of ca. 1.93 “1.93 Ga” (Kuorboaivi) rocks is 1.96 ± 0.14 Ga. Ga (mostly one discordant analysis/ sample). No The initial Pb isotopic composition suggests a indications of Archaean ages are found within juvenile Proterozoic source. this area.

5 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

5 U-PB RESULTS FROM ARCHAEAN INARIJÄRVI COMPLEX

The U-Pb data are available on fourteen mostly age 207Pb/206Pb age of 1.96 Ga suggests strong gneissic samples from the Archaean Inarijärvi Paleoproterozoic effect on this Archaean gneiss complex. In addition to old multi-grain TIMS data, (Fig. 3). zircon from three samples have been analyzed by The Käräjäsaari gneiss (A576) is located c. 4 km LA-MC-ICPMS. All data including isotope dia- SW from Kuorpasaari. The eight multi-grain TIMS grams are given in Appendix 1 and sample location analyses by Kouvo on euhedral elongated zircon in Figure 2. yield a chord, which gives an upper intercept age The old six TIMS analyses on zircon from the of 2744 ± 26 Ma (Fig. 4). Kuorpasaari gneiss (A167) are discordant providing a The two zircon analyses from a granite sample clear Archaean upper intercept age of 2737±10 Ma A1113 Iso-Roiro located ca. 4 km NE from Käräjäsaari (lower intercept at 470±33 Ma). The three analyses are badly discordant but consistent with an Archaean on titanite are reversely concordant, but the aver- age (Fig. 5).

96562 96558 A045993130 A1683 A0209 A0954 A1023

59833 A1024A1207 A0211 A0112 A0208 A1845 A0113A0115 A0207

A0461 A0210 A0458 A0463 A0168A0169

A0213

A0317 A0273 A0228 A0272 A0117 A0270

A0212 A1113 A1227 A0316 A0576 A0737 A0462 A0457A1957 A0503 A0166 A0227 A0225 A0455A0456 A0601 A0039 A0204A0419 A0269 A0170 A0088 A0502 A0203 A0087 A0171 A0451 A0318 A0276 A0156 A0111 A0504 A0268cA0268e

A0224 A1786 A1680 A0397 A1916 A1956 A0181A0355 A0372 A0540 A1506A1681A1682 A0891 A1504A1505 A0241A1508A1509 A1507

PSH-97-19.1 A1761

A2001 A0352 A0307A0527 A1670 A0266 Fig. 2. Geological map of Northernmost Finland showing sample localities.

6 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

0.54 A167 Kuorpasaari gneiss (TIMS) 2700

0.50 Titanites average Pb/Pb age 2500 0.46 1965 ± 34 Ma

U n=3 2300

238 0.42

Pb/ 2100 0.38 206 1900 0.34 TIMS Intercepts at 1700 0.30 470 ± 33 & 2737 ± 10 Ma MSWD = 4.4 (n=6) 1500 0.26 3 5 7 9 11 13 15 207Pb/235U Fig. 3. Concordia plot of U-Pb zircon (diamond) and titanite (triangle) data obtained from the Kuorpasaari gneiss A167.

0.54 A576 Käräjäsaari gneiss 2700

0.50 2500 0.46 U 2300

238 0.42

Pb/ 2100 0.38 206 1900 TIMS Intercepts at 0.34 A272B titanite 687 ± 89 & 2744 ± 26 Ma MSWD = 18 (n=8) 1700 0.30 A272A zircon 0.26 3 5 7 9 11 13 15 207Pb/235U Fig. 4. Concordia plot of U-Pb zircon (TIMS) data obtained from the Käräjäsaari gneiss A576. Results from the Nitsjärvi granite sample A272 are also shown.

7 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

The euhedral zircon grains from Suovavaara The discordant U-Pb data on zircon from the tonalite (A227) located in the SE part of the Inarijärvi Kittilompolo gneiss (A213) suggest an Archaean upper complex also give a clear Archaean upper intercept intercept age of ca. 2.7 Ga (Fig. 6). U-Pb age of 2760±19 Ma (Fig. 5).

0.55 A227 Suovavaara tonalite gneiss 2600 A227E +4,5 abr

0.45 A227F 4,3-4,5 abr 2200 A227B +4,6 U A227C 4,3-4,6 70-160 A227A total borax fusion 238 0.35 1800 Pb/ A227D 4,2-4,3 206

0.25 1400 A227 TIMS Intercepts at A1113A 641 ± 78 & 2760 ± 19 Ma A1113B MSWD = 11.1 (n=6) 1000 0.15 1 3 5 7 9 11 13 15 207Pb/235U Fig. 5. Concordia plot of U-Pb zircon (TIMS) data obtained from the Suovavaara gneiss A227. Results from the Isoroiro granite sample A1113 are also shown.

0.5 A213 Kittilompolo gneiss 2600

2200 0.4

U 1800

238 0.3

1400 Pb/

206 0.2 1000 TIMS Intercepts at 458 ± 54 & 2709 ± 35 Ma MSWD = 2.9 (n=5) 0.1

0.0 0 2 4 6 8 10 12 14 207Pb/235U Fig. 6. Concordia plot of U-Pb zircon (TIMS) data obtained from the Kittilompolo gneiss A213.

8 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

Based on one badly discordant borax fusion U-Pb Zircon grains are often anhedral and the conven- analysis on zircon, an Archaean age is also likely tional U-Pb data heterogenous and discordant. The for the fairly homogeneous Nitsjärvi granite (A272). analyses by MC-ICP-MS on pristine zircon domains In contrast, titanite in this sample suggests a U-Pb yield concordant data and a U-Pb age of 2520±9 Ma, age of 1.9 Ga (Fig. 4). whereas analyses on altered domain are discordant The U-Pb data are available on five samples (Fig. 9). An old borax-fusion analysis on titanite from the NE part of the Inarijärvi complex near the provides an age of 1.87 Ga. Norwegian border. The seven discordant U-Pb anal- Most LA-MC-ICP-MS analyses on zircon from yses on zircon from the porphyritic Pirivaara granite the deformed Partakko granodiorite (A270) yield con- (A226) yield an upper intercept age of 2603±34 Ma. cordant U-Pb data and an age of 2504±10 Ma (Fig. The 207Pb/206Pb age for slightly discordant titanite 10). A few analyses on altered domains are strongly is 2.19 Ga (Fig. 7). discordant and this explains the high discordancy An Archaean age is possible also for the in conventional data. The old borax-fusion analysis Isokivennotko granite (A1024), but data are too dis- on titanite concentrate suggests again an age of ca. cordant for a decent age estimate. 1.9 Ga. In terms of the two granitoids from Näätämö The Roavvi Tievja granite gneiss (A207) is located (A113, A115, Meriläinen 1976) neither has a well close to the northernmost edge of the Archean constrained age since the conventional multi-grain Inarijärvi Complex. Several of the conventional TIMS data on zircon are discordant and slightly het- multi-grain zircon fractions analysed provide a erogenous. An old borax-fusion analysis on titanite chord with intercepts at 2505±6 Ma and 465±12 Ma. from the Näätämö quartz diorite A115 gives an age Recently zircon was analysed by LA-SC-ICP-MS, of ca. 1.9 Ga (Fig. 8). yielding practically concordant data and an age of Three granitoid samples on the western zone 2524±8 Ma, which is considered as a best estimate of the Archean Inarijärvi complex yield ages of ca. of igneous age (Fig. 11). 2.5 Ga. One of these is the Akulahti tonalite (A212).

0.5 A226 Pirivaara granite 2600

2200 0.4

U 1800

238 0.3 A226 TIMS Intercepts at 389 ± 94 & 2603 ± 34 Ma 1400 Pb/ MSWD = 54 n=7

206 0.2 1000 A226 Titanite Pb/Pb age A1024 Isokivennotko granite 2192 ± 6 Ma 0.1 Intercepts at 504 ± 200 & 2527 ± 260 Ma MSWD = 16 n=4 0.0 0 2 4 6 8 10 12 14 207Pb/235U

Fig. 7. Concordia plot of U-Pb zircon (diamond) and titanite (triangle) data obtained from the Pirivaara granite A226. Results from the Isokivennotko granite sample A1024 are also shown.

9 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

0.54 Näätämö granitoids 2700 0.50 A115 Quartz diorite Intercepts at 484 ± 120 & 2486 ± 27 Ma 2500 0.46 MSWD = 23 n=7

2300 0.42 206 A115 Titanite Pb Concordia Age 2100 238U 0.38 1879 ± 10 Ma

1900 0.34 A113 Granite Intercepts at 1700 639 ± 150 & 2493 ± 35 Ma 0.30 MSWD = 15 n=7

1500 0.26 3 5 7 9 11 13 207Pb/235U Fig. 8. Concordia plot of U-Pb (TIMS) data obtained from the Näätämö granitoids A113 and A115.

data-point error ellipses are 2s

0.54 A212 Akulahti tonalite Concordia Age = 2520 ± 9 Ma 2600 0.50 n=9

0.46 2400 U

238 0.42 2200 Pb/ 0.38

206 2000

0.34 TIMS Zr Intercepts at 456 ± 140 & 2448 ± 20 Ma MSWD = 42 n=7 0.30 Titanite, TIMS Concordia Age = 1866 ±20 Ma 0.26 5 7 9 11 13 207Pb/235U Fig. 9. Concordia plot of U-Pb data obtained from the Akulahti tonalite A212. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

10 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s A270 Partakko granodiorite 0.6 Concordia Age = 2504 ± 10 Ma (n=14) 2600

U 2200 0.4 238 1800 Pb/

206 1400

0.2 1000

600 TIMS Intercepts at titanite Pb/Pb age (TIMS) 390 ± 75 & 2461 ± 24 Ma 1891 ± 28 Ma MSWD = 18 (n=5) 0.0 0 2 4 6 8 10 12 14 207Pb/235U Fig. 10. Concordia plot of U-Pb data obtained from the Partakko granodiorite A270. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

data-point error ellipses are 2s

0.5 A207 Roavvi Tievja granite 2600

2200 0.4

U 1800 0.3 238 207Pb/206Pb age 1400 Pb/ 2524 ± 8 Ma MSWD = 4.6 n=27 206 0.2 1000 (LA-ICPMS)

600 0.1 Titanite TIMS TIMS Intercepts at 207Pb/206Pb age 465±12 & 2505 ± 6 Ma 2005±23 Ma MSWD = 3.0, n=10 0.0 0 2 4 6 8 10 12 14 207Pb/235U Fig. 11. Concordia plot of U-Pb data obtained from the Roavvi Tievja granite A207. LA-SC-ICPMS analyses pre- sented as error ellipses and TIMS data as dots.

11 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

6 U-PB RESULTS FROM PALEOPROTEROZOIC ROCKS: SILISJOKI & LUOSSAVARRI SUITES AND KAAMANEN COMPLEX

The areas to the west and northwest of the Archaean cordant, which is also the case with many recent Inarijärvi Complex consist of Paleoproterozoic rocks. analyses by laser MC-ICP-MS (Fig. 12). However, In the recent geological map these are termed data on low-U domains are concordant yielding an Silisjoki & Luossavarri suites and Kaamanen com- age of 1937±15 Ma. plex which is the eastern marginal zone of the The deformed trondhjemite from Nuottalvaara Lapland granulite belt (Nironen et al. 2016). The (A211) is located seven kilometres east of Keniskoski. conventional U-Pb results on zircon from several The bulk of the U-Pb analyses on zircon by LA-MC- samples are discordant and consistent with an age of ICP-MS provide a chord, which gives an upper 1.90-1.95 Ga (Meriläinen 1976). Many of these sam- intercept age of 1926±16 Ma. Two analyses from ples have been reanalysed by LA-MC-ICP-MS and outer domains in grain 4 yield reversely discordant the U-Pb data including images of analysed zircon data, whereas an analysis from the high-U core (4a, and isotope diagrams are given in the Appendix 1. Appendix 1) is normally discordant. There are also The Keniskoski tonalite (A112) is located five kilo- two grains which suggest older ages due to zircon metres east of the granulite belt proper and in the inheritance (Fig. 13). current geological map belongs to the Silisjoki Further east a deformed tonalite was collected suite. A sample from this gneissic rock was col- from Roullekuoddetsohkka (A208). The bulk of the lected (in 1964) from a quarry close to the Inari- U-Pb LA-MC-ICP-MS analyses on zircon extracted Utsjoki road. Two old borax fusion U-Pb analyses from this sample in are concordant and provide an on mostly euhedral magmatic zircon are very dis- age of 1915±7 Ma (Fig. 14).

data-point error ellipses are 2s 0.5 A112 Keniskoski tonalite Intercepts at 2200 0.4 414 ± 40 & 1928 ± 26 Ma MSWD = 7.9 n=21 (all) 1800 0.3 low U zircon 206 Pb 1400 Concordia Age 238 1937 ±15 Ma U 0.2 (n=7) 1000 TIMS

0.1 600

200

0.0 0 2 4 6 8 207Pb/235U Fig. 12. Concordia plot of U-Pb zircon data obtained from the Keniskoski tonalite A112. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

12 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s 0.6 A211 Nuottalvaara trondhjemite

0.5 2600

2200 0.4 U 1800 238 0.3

Pb/ 1400

206 0.2 Intercepts at 1000 TIMS 176 ± 160 & 1926 ± 16 Ma MSWD = 2.7 n=15 0.1 600

0.0 0 2 4 6 8 10 12 14 207Pb/235U Fig. 13. Concordia plot of U-Pb zircon data obtained from the Nuottalvaara trondhjemite A211. LA-MC-ICPMS analyses presented as error ellipses and TIMS analysis as dot.

data-point error ellipses are 2s 0.41 A208 Roullekuoddetsohkka tonalite 0.39 Concordia Age = 1915 ± 7 Ma n=12 (low U data)

0.37 2020 1980 206 1940 Pb 0.35 1900 238 U 1860 0.33 1820

0.31 Average Pb/Pb age 1906 ± 8 Ma MSWD = 1.5, n=15 (all)

0.29 4.8 5.2 5.6 6.0 6.4 207Pb/235U Fig. 14. Concordia plot of the LA-MC-ICPMS U-Pb analyses on zircon obtained from the Roullekuoddetsohkka tonalite A208.

13 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

The fourth gneissic sample located in the Silisjoki of 1925±7 Ma (Fig. 17). Inherited older zircon was suite area of the recent map was collected by Mogens also obtained. Marker from Utsjoki (59833). Again, the conven- Two badly discordant U-Pb TIMS analyses on tional TIMS data are badly discordant. Some laser zircon was also obtained from the Uhtsaskaidas gab- MC-ICP-MS analyses on high-U domains are also bro (A954), located ca. seven kilometres east from discordant, but the bulk of the data yield concordant sample A209 (Fig. 17). results and a U-Pb age of 1915±9 Ma which is con- Further to the northwest, near the Norwegian sidered as a best estimate for igneous age (Fig. 15). border, a sample has been collected from Vetsikko The U-Pb zircon data are available on ten igne- quartz diorite (A459). A U-Pb analysis using the ous samples (A116, A209, A458, A459, A463, A954, chemical abrasion TIMS method yielded concordant A1023, 93130, 96558, 96562), which in the recent data and an age of 1936±3 Ma, which is supported geological map are assigned to the Luossavarri suite by the LA-MC-ICP-MS analyses giving an age of (Nironen et al 2016). 1943±6 Ma (Fig. 18). One of these is the Luossajauri gabbro (A1023) A few kilometres to the northeast from A459 close to the Norwegian border. Fourteen U-Pb anal- a sample 93130 from porphyritic granitoid was yses on zircon by LA-MC-ICP-MS are concordant obtained. Again, LA-MC-ICP-MS data on high-U producing an age of 1925±5 Ma. The discordant domains as well as multi-grain U-Pb TIMS analy- TIMS data are consistent with this age (Fig. 16). ses are discordant. Five concordant U-Pb analyses Another sample from this family is the tonalitic yield an age of 1897±10 Ma (Fig. 19). Two old TIMS gneiss from Keinodakoaivi (A209). The conventional analyses obtained using the borax-fusion digestion TIMS analyses and laser spots on high-U domains method from the nearby quartz diorite sample A116- yield strongly discordant data, but again most data Sirma are also discordant and compatible with the by LA-MC-ICP-MS are concordant providing an age age obtained from other samples.

data-point error ellipses are 2s

0.5 59833 Utsjoki gneiss

2200 0.4

U 1800

238 0.3

1400 Pb/

206 0.2 1000 Concordia age 1915 ± 9 Ma (n=9) 600 0.1 TIMS Intercepts at Intercepts at 205 ± 12 & 1873 ± 10 Ma 424 ± 45 & 1913 ± 14 Ma 200 MSWD = 1.2 n=3 MSWD = 1.4 n=15 (all) 0.0 0 2 4 6 8 10 207Pb/235U Fig. 15. Concordia plot of U-Pb zircon data obtained from the Utsjoki gneiss sample 59833. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

14 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s 0.4

A1023 Luossajauri gabbro 2000 Concordia Age = 1925 ± 5 Ma n=14 (all) 1800

0.3

U 1600 238 1400 Pb/

206 1200 0.2 TIMS Intercepts at 1000 399 ± 22 & 1935 ± 16 Ma MSWD = 3.8 (n=4) 800

0.1 1 2 3 4 5 6 207Pb/235U

Fig. 16. Concordia plot of U-Pb zircon data obtained from the Luossajauri gabbro A1023. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

data-point error ellipses are 2s

A209 Keinodakoaivi tonalite 2200 0.4

1800 0.3

1400 206Pb 238 0.2 Concordia Age = U 1000 A209 TIMS 1925 ± 7 Ma MSWD= 0.1 n=16 A954A TIMS 0.1 600 A954B TIMS

0.0 0 2 4 6 8 207Pb/235U Fig. 17. Concordia plot of U-Pb zircon data obtained from the Keinodakoaivi tonalite A209. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

15 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

data-point error ellipses are 2s A459 Vetsikko quartz diorite 0.39 Concordia Age = 1943 ± 6 Ma n=16 (all) 2040 0.37 2000

U 1960

238 0.35 1920 1880 Pb/ 1840

206 0.33 1800 1760 A459B CA-TIMS 0.31 Concordia Age = 1936 ± 3 Ma

A459A TIMS (borax fusion) 0.29 4.6 5.0 5.4 5.8 6.2 6.6 207Pb/235U Fig. 18. Concordia plot of U-Pb zircon data obtained from the Vetsikko quartz diorite A459. LA-MC-ICPMS analyses presented as error ellipses and TIMS analysis as dot.

data-point error ellipses are 2s 0.5 93130 Vetsikko granitoid

Concordia Age = 1897 ± 10 Ma 2200 0.4 n=5

1800 U 0.3 238 1400 A116 Sirma zircon Pb/ 0.2

206 1000

TIMS Intercepts at 0.1 600 280 ± 290 & 1911 ± 110 Ma MSWD = 7.7 n=4 200

0.0 0 2 4 6 8 207Pb/235U Fig. 19. Concordia plot of U-Pb zircon data obtained from the Vetsikko granitoid sample 93130. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots. The old TIMS zircon analyses from the Sirma sample A116 are also shown.

16 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

A quartz diorite from the Isoköngäs sample 96562 Again, LA-MC-IC-MS results are concordant pro- contains zircon grains on which the LA-MC-ICP-MS viding an age of 1929±6 Ma, which is consistent data are concordant providing an age of 1906±6 Ma. with the TIMS data. In fact, one analysis which was The discordant multi-grain TIMS data are consist- made using chemical abrasion treatment, yielded a ent with this age (Fig. 20). Discordant TIMS data concordant TIMS U-Pb age of 1928±3 Ma (Fig. 23). were also obtained from a diorite collected further The Kaamanen complex in the recent geologi- east in Polmak (Fig. 21). cal map seems to contain three old gneissic sam- One of the large igneous massifs of the Luossavarri ples which were used for age dating. One of these suite is located further south in Kuktshvaara (A463). is the Syysjärvi tonalite (A117), which was selected Several U-Pb TIMS data points on zircon suggest- for LA-ICPMS studies. Excluding two strongly dis- ing an age of ca. 1.95 Ga were already shown in cordant analyses, the U-Pb data on zircon yield a Concordia diagram by Meriläinen (1976). The an average Pb/Pb age of 1897±8 Ma. The two old LA-MC-ICP-MS analyses on zircon confirm this age multigrain TIMS analyses and TIMS analyses on and suggest a concordia age of 1944±5 Ma (Fig. 22). two other felsic gneiss samples (A39 Kenttäsaaret Another quartz diorite sample has been collected and A170 Tsharmijärvi) are consistent with this age a few kilometres west in Mieraslompolo (A458). (Fig. 24).

0.40 96562 Isoköngäs quartz diorite 0.38 Concordia Age = 1906 ± 6 Ma n=11 (/12) 2000 0.36 1960 1920 U 0.34 1880 238 1840 1800

Pb/ 0.32 1760

206 1720 0.30 1680 1640 TIMS Intercepts at 379 ± 35 & 1911 ± 6 Ma 0.28 MSWD = 1.3 (n=4)

0.26 4.0 4.4 4.8 5.2 5.6 6.0 6.4 207Pb/235U Fig. 20. Concordia plot of U-Pb zircon data obtained from the Isoköngäs quartz diorite sample 96562. LA-MC- ICPMS analyses presented as error ellipses and TIMS data as dots.

17 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

96558 Polmak 2000 0.36 TIMS Intercepts at 293 ± 70 & 1916 ± 10 Ma 1900 0.34 MSWD = 1.8 U 1800

238 0.32 Pb/ 1700 C +4.2 transparent

206 0.30 A +4.2 a16h

1600 0.28 B +4.2 a6h

1500 0.26 3.2 3.6 4.0 4.4 4.8 5.2 5.6 6.0 207Pb/235U Fig. 21. Concordia plot of U-Pb TIMS zircon data obtained from the Polmak sample 96558.

0.40 A463 Kuktshvaara quartz diorite 0.38 Concordia Age = 1944 ± 5 Ma 2040 n=17 (all) 2000 0.36 1960 1920 U 0.34 1880 238 1840 1800

Pb/ 0.32 1760

206 1720 0.30 1680 TIMS Intercepts at 1640 438 ± 52 & 1947 ± 5 Ma MSWD = 2.9 n=9 0.28

0.26 4.0 4.4 4.8 5.2 5.6 6.0 6.4 207Pb/235U Fig. 22. Concordia plot of U-Pb zircon data obtained from the Kuktshvaara quartz diorite A463. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

18 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s

0.40 A458 Mieraslompolo quartz diorite Concordia Age = 1929 ± 6 Ma (n=15 all) 2050

0.36 1950 U 1850 238

0.32

Pb/ 1750 206 1650

0.28 TIMS Intercepts at 324 ± 56 & 1930 ± 8 Ma MSWD = 5.7 (n=7)

0.24 3.8 4.2 4.6 5.0 5.4 5.8 6.2 6.6 207Pb/235U Fig. 23. Concordia plot of U-Pb zircon data obtained from the Mieraslompolo quartz diorite A458. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

data-point error ellipses are 2s 0.5 A117 Syysjärvi tonalite Average Pb/Pb age 0.4 1897 ± 8 Ma 2100 MSWD = 2.6, n=21 1900

206 Pb 0.3 1700 A39A zircon 238U 1500 A170A zircon 1300 TIMS 0.2 1100 Intercepts at 461 ± 98 & 1888 ± 15 Ma MSWD = 4.9 n=23 (all)

0.1 1.5 2.5 3.5 4.5 5.5 6.5 7.5 207Pb/235U Fig. 24. Concordia plot of U-Pb zircon data obtained from the Syysjärvi tonalite A117. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots. The old TIMS zircon analyses from samples A39 and A170 are also shown.

19 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

7 U-PB RESULTS FROM LAPLAND GRANULITE COMPLEX ENDERBITES, PARAGNEISSES AND DYKES

The Lapland granulite complex of the north-eastern data on igneous rocks including isotope diagrams Fennoscandian Shield is dominated by blastomylo- are given in Appendix 2 and cover ten samples from nitic migmatitic metagreywackes and a deformed, the enderbite series, two granites and two samples structurally conformable norite–enderbite series from the appinite suite (Mutanen 2011). (Meriläinen 1976, Daly et al. 2006, Tuisku et The migmatitic tonalite from Koskivuono (A87) al. 2012). In the recent geological map these are is one of the samples of the norite-enderbite assigned as Saariselkä and Kuttura suites, respec- series and locates between the Akujärvi (A111) and tively (Nironen et al. 2016, Luukas et al. 2017). Myösäjärvi (A269) samples discussed by Tuisku Several samples from enderbites already reported et al. (2012). Before instruments for spot analy- by Meriläinen (1976) suggested U-Pb zircon ages ses were available, attempts were made by Kouvo of ca. 1.9 Ga. Subsequently, U-Pb ages of 1.91-1.92 and assistants to pick up certain zircon types, par- Ga were obtained by SIMS on magmatically zoned ticularly “microgems”, for U-Pb analyses. Thus, zircon while homogeneous metamorphic zircon several TIMS analyses have also been made from domains yielded ages of 1.88 –1.90 Ga (Tuisku & this sample in order to estimate the age of complex Huhma 2006, Tuisku et al. 2012). These results geological evolution. However, the U-Pb analyses on by SIMS were based on analyses from six samples zircon scatter and no reliable ages can be obtained. (A111, A269, A1509, A1681-3). Here our aim is to Instead, a TIMS analysis on monazite yields con- report on all unpublished data mostly from the old cordant age at 1909±3 Ma (Fig. 25). samples discussed by Meriläinen (1976). The U-Pb

2020 A87 Koskivuono quartz diorite 0.36 1980 1940 1900 A87C monazite 0.34 1860 206Pb 1820 238 0.32 1780 U A87 Monazite Concordia Age =

0.30 1909 ± 3 Ma

0.28 4.6 5.0 5.4 5.8 6.2 207Pb/235U Fig. 25. Concordia plot of U-Pb TIMS data obtained on zircon and monazite from the Koskivuono quartz diorite A87.

20 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

Another lineated tonalite a few kilometres north An old U-Pb analysis on zircon using the borax at Nuoransuunselkä (A88) also contains monazite, on fusion method from the nearby Vellivaara gneiss which two TIMS analyses are concordant suggest- (A451) also yielded concordant data and an age of ing an age of 1906±3 Ma (Fig. 26). One analysis on 1917±5 Ma (Fig. 27). “microgem” zircon concentrate also yielded con- Similarly, a borax fusion TIMS analysis on zir- cordant data and an age of 1901±4 Ma. con from the Sotajoki tonalite (A241), located near

0.36 A88 Nuoransuunselkä quartz diorite A88C +4,6 a2h 1920 "microgems" A88D monazite 0.34 yellow 1880 A88E monazite red pigm. abr 1840 U

238 1800 0.32 Monazite 1760 Pb/ average Pb/Pb age 1906 ± 3 Ma 206 MSWD = 1.4 n=2 0.30 A88C zircon ("gem") Concordia Age = 1901 ± 4 Ma 0.28 4.5 4.7 4.9 5.1 5.3 5.5 5.7 207Pb/235U Fig. 26. Concordia plot of U-Pb TIMS data obtained on zircon and monazite from the Nuoransuunselkä quartz diorite A88.

data-point error ellipses are 2s

0.351 A451 Vellivaara gneiss zircon borax fusion analysis Concordia Age = 1917 ±5 Ma 1930 0.349 1926

U 1922

238 0.347 1918

Pb/ 1914

206 0.345 1910

0.343 A241 Sotajoki quartz diorite zircon borax fusion analysis Concordia Age = 1923 ± 5 Ma 0.341 5.54 5.58 5.62 5.66 5.70 207Pb/235U Fig. 27. Concordia plot of old U-Pb TIMS data obtained on zircon from the Sotajoki A241 and Vellivaara A451.

21 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma the SW edge of the granulite belt, is concordant at sample A203. The U-Pb data available scatter with 1923±5 Ma. Pb/Pb ages ranging from 1.9 to 2.08 Ga. The five The primary goal for dating the two quartz dior- analyses on clear multifaceted “microgem” zircon itic samples A203 Lammaspää ja A204 Jurmukoski are close to Concordia suggesting an age of 1920±7 has been to evaluate the existence of Archean crust Ma (Fig. 28). The U-Pb analyses on zircon from the within the granulite belt. A large amount of mul- Jurmukoski sample yield roughly similarly scattered tigrain zircon TIMS analyses have been made on data (Fig. 29).

data-point error ellipses are 2s

2080 0.38 A203 Lammaspää quartz diorite 2040 0.37 2000

U 0.36 1960 238

0.35

Pb/ 1920

206 "microgem zircon" 0.34 1880 Average Pb/Pb age 1920 ± 7 Ma 1840 MSWD = 19 0.33 n=5

0.32 5.0 5.4 5.8 6.2 6.6 7.0 207Pb/235U Fig. 28. Concordia plot of U-Pb TIMS data obtained on zircon from Lammaspää (A203) quartz diorite.

data-point error ellipses are 2s 0.38 A204 Jurmukoski quartz diorite 2000 zircon 1900 0.34

1800 U

238 1700 0.30 Pb/ 1600 A204 +4.6 zircons 206 average Pb207/206 age 0.26 1935 ± 17 Ma MSWD = 16 (n=3)

0.22 4 5 6 7 207Pb/235U Fig. 29. Concordia plot of U-Pb TIMS data obtained on zircon from Jurmukoski (A204) quartz diorite.

22 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

The old TIMS data available on the other two granite (A462) are discordant and provide a chord quartz dioritic samples further north in Pailovaara which gives an upper intercept age of 1904±9 Ma (A225) and Karnasrattaoaivi (A228) suggest U-Pb (Fig. 29). The other granite collected from Appisjoki zircon ages of ca. 1.9 Ga (Fig. 30). (A1786) contained equant clear zircon which yields a Two magnetite bearing granites from the Lapland slightly discordant U-Pb result with a 207Pb/206Pb granulite complex have been targets for dating. The age of 1908±3 Ma. The sample also contained mona- old U-Pb analyses on zircon from the Vuoskuljärvi zite which gives an age of 1903±3 Ma (Fig. 31).

0.37

A225 Pailovaara 1950 0.35 quartz diorite 1904 ± 6 Ma & 400±400 Ma A225B borax 1850 A225A 0.33 MSWD = 1, n=2

1750 0.31 U A228 Karnasrattaoaivi

238 1650 zr (borax fusion) 0.29 Pb/ 1550 0.27 206

1450 0.25 A462 Vuoskuljärvi granite Intercepts at 0.23 284 ± 35 & 1904 ± 9 Ma MSWD = 1.6 n=4 0.21 3 4 5 6 207Pb/235U Fig. 30. Concordia plot of old U-Pb TIMS data obtained on zircon from the Pailovaara (A225), Karnasrattaoaivi (A228) and Vuoskuljärvi (A462) samples.

data-point error ellipses are 2s 0.36 A1786 Appisjoki granite A1786 Monazite 0.35 1930 average Pb/Pb age 1903 ± 3 Ma 1910 A1786D monazite

U 1890 0.34

238 1870 A1786B 1850 Pb/ 0.33 A1786B Appisjoki "granulite zircon" 206 Pb/Pb age 1908 ± 3 Ma A1786A 0.32 A1786A Appisjoki long turbid zircon Pb/Pb age 1922 ± 3 Ma

0.31 5.1 5.2 5.3 5.4 5.5 5.6 5.7 207Pb/235U Fig. 31. Concordia plot of U-Pb TIMS data obtained on zircon and monazite from the Appisjoki granite A1786.

23 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

Geological research by Tapani Mutanen (2011) no deformation (Mutanen 2011). An abundance of highlighted the existence of appinite igneous suite clear, good zircon was obtained from the Suhuvaara within the Lapland granulite complex. One body of sample. The three U-Pb analyses by TIMS are close this group is the Palloaivi intrusion and in fact the to Concordia and yield an average Pb/Pb age of two old samples discussed above, A225 and A462, 1904±6 Ma which was subsequently confirmed by have been collected from this distinct aeromagnetic LA-MC-ICP-MS analyses yielding a Concordia age anomaly. of 1910±6 Ma (Fig. 33). The U-Pb ages of zircon from The dioritic rock near the Pielpajärvi wilderness the appinites (Pielpajärvi, Suhuvaara) sets the lower church (A503) is also one of the isotope samples age limit of the granulite deformation. of this rock family. Before the possibility for spot Meriläinen (1976) reported isotopic results on analyses, attempts were made to separate zircon several supracrustal garnet-cordierite gneisses on the basis of morphology under the supervision from the Lapland granulite complex, but no data of O. Kouvo. The U-Pb TIMS data available scat- were given. Using SIMS technique together with ter but including the four concordant analyses on Sm-Nd TIMS method the isotope characteristics of clear “microgem” zircon, an age of 1905±2 Ma can these migmatitic paragneisses from the Lapland be calculated (Fig. 32). This is considered the best granulite belt were further studied by Tuisku & estimate for the igneous age; the data also clearly Huhma (2006). Their data obtained from five sam- show zircon inheritance from older crustal material. ples (A1504-A1509) showed that detrital zircon A few kilometres northwest from Pielpajärvi a grains were derived from 1.94 − 2.9 Ga old source sample was collected from the Suhuvaara appin- rocks and a younger, 1905 −1880 Ma population of ite dyke (A1957), belonging to the Inari intrusion homogeneous zircon was formed during regional cluster (Mutanen 2011). The dyke cuts perpendicu- metamorphism. Garnet whole rock Sm-Nd ages larly through granulites along its 4.5 km length from leucosomes in the range 1880 − 1886 ± 7 Ma and has fine-grained chilled margins and shows are concurrent with the growth of the youngest

data-point error ellipses are 2s 0.365 A503 Pielpajärvi diorite (appinite) 1990

1970 0.355 1950

U 1930 238 0.345 1910

Pb/ 1890

206 "microgem zircon" 1870 (d>4.6 g/cm3) 0.335 Concordia Age = 1905 ± 2 Ma n=4

0.325 5.2 5.4 5.6 5.8 6.0 6.2 207Pb/235U Fig. 32. Concordia plot of U-Pb TIMS data obtained on zircon from the Pielpajärvi appinite A503.

24 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s

0.40 A1957 Suhuvaara gabbro (appinite)

TIMS, zircon 0.38 average Pb/Pb age 1904 ± 6 Ma 2020 1980 U 0.36 n=3 (red) 1940 238 1900 0.34 Pb/ 1860 LA-ICP-MS 1820 206 Concordia Age 0.32 1780 1910 ± 6 Ma n=34

0.30

0.28 4.6 5.0 5.4 5.8 6.2 6.6 207Pb/235U Fig. 33. Concordia plot of U-Pb zircon data obtained from the Suhuvaara gabbro A1957. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as red dots.

metamorphic zircon (Tuisku & Huhma 2006). The TIMS analyses the age of these 3-4 mm large titan- detrital population shares similarities with the ites has been estimated at 1907±10 Ma (Fig. 35). Svecofennian and Upper Kalevian metasediments During the intensive mapping in the Inari- (e.g. Huhma et al. 1991, Lahtinen et al. 2009, 2010). Utsjoki area, dating samples were also collected Here our aim is to report all unpublished from the “anatectic dykes” (Meriläinen 1976). Here data mostly from the old samples discussed by we report the U-Pb TIMS data from five granitic and Meriläinen (1976). The U-Pb data obtained by TIMS two mafic dykes. The U-Pb data, including isotope on six samples are given in Appendix 3. The old diagrams, are given in Appendix 3. multi-grain TIMS data are discordant and scattered One of the granitic dykes was taken from the providing Pb/Pb ages from 1.95 to 2.1 Ga (Fig. 34) Törmänen outcrop where garnet-cordierite gneiss and are thus compatible with the sims data reported (A268c) was also processed. The old U-Pb TIMS by Tuisku & Huhma (2006) for the other metasedi- data on the dyke zircon (A268e), mostly obtained mentary samples. The U-Pb TIMS data on mona- by the borax fusion method, yielded a chord with zite have been obtained from eight supracrustal intercepts at ca. 1.91 and 0.47 Ga. Two analyses on samples and include six old analyses made using clear “microgem” zircon are nearly concordant with the borax fusion method. These, together with five a 207Pb/206Pb age of 1906±5 Ma. A borax fusion more recent analyses on monazite, yield an average analysis on monazite is concordant at 1890±5 Ma Pb/Pb age of 1909±3 Ma (Fig. 34). (Fig. 36). This is younger than the age obtained Near the western margin of the granulite com- from monazite extracted from country rock garnet- plex abundant titanite was obtained from the cordierite gneiss A268c, which yielded an age of Marastoäytsi gneiss sample A156. Based on two old 1906±7 Ma (above).

25 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

0.40 Grt-crd gneisses/ Monazites Average Pb/Pb age 2080 0.38 1909 ± 3 Ma MSWD = 5.2 n=11 2040

2000

U 0.36 A214A 1960

238 A214B 1920 A276A A214C A214E A214D Pb/ 1880 A268cA 0.34 A318D 206 A268cB 1840 A318A A318C A317A A171A 0.32 A318B

0.30 5.0 5.4 5.8 6.2 6.6 207Pb/235U

Fig. 34. Concordia plot of U-Pb TIMS data obtained on zircon and monazite from the supracrustal garnet-cordierite gneisses within the Lapland granulite complex.

data-point error ellipses are 2s

1990 0.36 A156 Marastoäytsi gneiss 1970

1950

U 0.35 1930 238

Pb/ 1910 206

1890 Titanite 0.34 Pb/Pb age

1870 1907 ± 10 Ma

1850

0.33 5.1 5.3 5.5 5.7 5.9 6.1 207Pb/235U Fig. 35. Concordia plot of U-Pb TIMS data obtained on titanite from the Marastoäytsi gneiss A156.

26

Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

Fig. 36. Concordia plot of U-Pb TIMS data obtained on zircon and monazite from the “anatectic dykes”.

The U-Pb TIMS results from the other four Zircon was also obtained from the mafic dykes samples, A166-Pääsaaret, A316-Korppikuru, A419 in the Mutusjärvi outcrop (A455-6). The old seven Solojärvi and A457 Mutusjärvi provide roughly con- U-Pb TIMS analyses on zircon give a chord with sistent results. intercepts at 388 ± 40 & 1901 ± 5 Ma (Fig. 37). The old TIMS data (using borax fusion) on mona- The granulite belt was intruded by the Nattanen zite are available on four samples and these yield type granites at 1.77 Ga (Heilimo et al. 2009). A por- an average 207Pb/206Pb age of 1893 ± 8 Ma, which phyry dyke ca. 50 kilometres north of Nattanen in is younger than the average Pb/Pb age of 1909±3 Hangasoja (A1680) has provided zircon, on which Ma calculated for monazite in the garnet-cordierite one discordant TIMS analysis plots on a chord gneisses above. defined by Nattanen granite (Appendix 3).

27 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

Fig. 37. Concordia plot of U-Pb TIMS data obtained on zircon from the Mutusjärvi dykes.

8 U-PB RESULTS FROM VASKOJOKI ANORTHOSITE AND VUOTSO COMPLEX

Two dating samples were collected from the images (yya, yyb in Fig. 39). On the other hand, Vaskojoki (or Angeli) anorthosite in the 1970s. Five some low-U grains are clearly visible in BSE, but U-Pb TIMS analyses from zircon and one from very light (white) in the CL images (4a in Fig. 39). titanite have been made on the sample Närrijärvi Under the binocular microscope the low-U zircon A601. Excluding an analysis on rounded zircon grains are very clear and colourless while the high-U grains, the data yield slightly discordant data with grains (both 1.87 Ga and 2.4 Ga) are transparent with an average Pb/Pb age of ca. 1.92 Ga (Appendix 4). a typical zircon colour. Some data have been omitted The age obtained from titanite is slightly younger at from the final evaluation due to the very low level 1903±10 Ma (Fig. 38). The two TIMS analyses from of Pb, high amount of common lead or discordancy. the other sample A737-Vaddejärvi suggest older ages. The results obtained suggest an igneous age Subsequently, zircon from this sample was of 1920±8 Ma, together with some metamorphic mounted and analysed by LA-MC-ICP-MS. A range effects and inheritance. Bernard-Griffiths et al. of zircon types and ages is evident from the 32 (1984) published a U-Pb zircon age of 1906±5 Ma analyses available. Most data are concordant at ca. for the Vaskojoki anorthosite although this was 1.9 Ga, but a few grains are older suggesting ages based on three strongly discordant analyses. up to 2.43 Ga, thus explaining the multi-grain TIMS The western boundary zone between the Lapland data (Appendix 4, Fig. 38). granulite complex and the Central Lapland area A closer look reveals that the analyses on low-U has been called the Tanaelv belt or in the recent zircon (U mostly below 100 ppm) suggest an age of geological map the Vuotso complex (Luukas et al. 1920 ± 8 Ma, whereas the few analyses on high-U 2017). It contains rocks which have been metamor- zircon (U>700 ppm) give an age of 1874±7 Ma (Fig. phosed at high pressures and temperatures (Tuisku 39). Some low-U zircon grains are totally invis- & Makkonen 1999, Tuisku et al. 2006, Hölttä & ible in the BSE images, but appear dark in the CL Heilimo 2017).

28 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s

A737 Vaddejärvi anorthosite

0.50

Average Pb/Pb age 2400 1903 ± 12 Ma MSWD = 7.9 n=17

U (U> 20 ppm) 0.40

238 Concordia Age = 2000 2430 ±16 Ma

Pb/ n=3 206 TIMS 0.30 1600

1200 0.20 1 3 5 7 9 11 13 207Pb/235U

Vaskojoki Anorthosite data-point error ellipses are 2s 0.43 A737 Average Pb/Pb age 0.41 1920 ± 8 Ma MSWD = 2.8 n=14 (U<270 ppm) 0.39 A737 Average Pb/Pb age 2060 1874 ± 7 Ma 0.37 2020 U MSWD = 0.086 n=4 1980

238 (U>700 ppm) 1940 0.35 1900 A601B round Pb/ 1860 0.33 A601C +4,2 -50 206 1820 1780 A601A long xls 1740 0.31 A601D total A601E dark xls A601 TIMS average Pb/Pb age 0.29 A601 titanite 1917 ± 10 Ma Pb/Pb age 1903 ±10 Ma MSWD = 19 n=4 0.27 4.4 4.8 5.2 5.6 6.0 6.4 6.8 207Pb/235U Fig. 38. Concordia plot of U-Pb zircon data obtained from the Vaskojoki anorthosite samples A601 and A737. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

29 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

A737 Anorthosite zircon 2450

2350

2250

2150

Pb/Pb age (Ma) Pb/Pb age 2050

4a: U =26 ppm 1950 1920 ±8 Ma 10a: U=1300 ppm yya: U=10 ppm 1874±7 Ma 1850 0 200 400 600 800 1000 1200 1400 U (ppm)

Fig. 39. Images of the analysed zircon grains, sample A737.

The unpublished U-Pb data are available on five intrudes amphibolites and gneisses. Abundant zir- old samples within the Vuotso complex and together con extracted from the sample showed a range of with isotope diagrams are shown in Appendix 4. morphological varieties. Attempts have been made One of these is the granite from Lemmekäspalo by Kouvo and assistants to pick up these for analy- A504 ca. 15 kilometres south of the Vaskojoki ses, but no clear age results were obtained. The two anorthosite. The discordant TIMS results on zir- U-Pb TIMS analyses on titanite concentrate give con already shown by Meriläinen (1976) suggested concordant results and an age of 1904±20 Ma. an age of ca. 2.38 Ga. Subsequently, using LA-MC- The laser-MC-ICP-MS analyses on zircon pro- ICP-MS an average Pb/Pb age of 2482±8 Ma can vide a range of ages from 2.5 to 1.9 Ga. This range be calculated for practically concordant data. Some can be obtained within a single crystal, e.g. grain data points excluded from this calculation yield 10 (Fig. 42). This is also evident from the analyses, younger or discordant results and help to explain which were started from the core and later drilled the multigrain conventional results (Fig. 40). through into much younger rim domains (Appendix Around 20 kilometres south of Lemmekäspalo 4). An age of 1882±17 Ma calculated from the rim a sample has been taken from the Pennasnjarga domains likely represents the best estimate for the gneiss A372. Most spots on zircon analysed by laser age of the granite. MC-ICP-MS yield concordant U-Pb data and an Further north, sample A502-Kartojärvi was col- age of 2509±8 Ma. A few data points from more lected from a pegmatitic granite crosscutting altered zircon provide younger or discordant results, amphibolite. The seven conventional U-Pb analy- explaining the discordant conventional TIMS data ses on turbid high-U zircon give discordant data, (Fig. 41). which suggest an upper intercept age of 1885±22 Ma A few kilometres west of A372 a sample was (Fig. 43). taken from the Kahvijänkä granite A397 which

30 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s 0.7 A504 Lemmekäspalo granite LA-MCICPMS 0.6 average Pb/Pb age 2482 ± 8 Ma MSWD = 0.8 n=17 (U<800 ppm) 0.5 2600 U

238 2400 Pb/ 2200 206 0.4 2000

1800 0.3 1600 TIMS Intercepts at 434±43 & 2383 ± 20 Ma MSWD = 1.5 n=11

0.2 3 5 7 9 11 13 207Pb/235U

Fig. 40. Concordia plot of U-Pb zircon data obtained from the Lemmekäspalo granite A504. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

data-point error ellipses are 2s

A372 Pennasnjarga gneiss

0.55

2600 U 0.45 2400 238

2200 Pb/

206 2000 Concordia Age = 0.35 TIMS 2509 ± 8 Ma n=17/22

0.25 5 7 9 11 13 207Pb/235U Fig. 41. Concordia plot of U-Pb zircon data obtained from the Pennasnjarga gneiss A372. LA-MC-ICPMS analyses presented as error ellipses and TIMS data as dots.

31 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

data-point error ellipses are 2s

A397 Kahvijänkä granite 0.65

0.55 2800 U 2400 238 0.45 A397-10a Concordia Age =

Pb/ 2494 ± 30 Ma 2000

206 0.35 LA-MCICPMS 1600 Concordia Age = 0.25 1882 ±17 Ma 1200 TIMS titanite n=6 1904 ± 20 Ma TIMS 0.15 0 4 8 12 16 207Pb/235U

Fig. 42. Concordia plot of U-Pb data obtained from the Kahvijänkä granite A397. LA-MC-ICPMS analyses on zircon presented as error ellipses and TIMS data as dots.

0.38

A502 Kartojärvi granite 1900 0.34

1700 0.30 U

238 1500 0.26 Pb/

206 1300 0.22 A502 Kartojärvi granite 1100 Intercepts at 0.18 291 ± 60 & 1885 ± 22 Ma MSWD = 6.2 (n=7, TIMS) 900 0.14 1 2 3 4 5 6 207Pb/235U Fig. 43. Concordia plot of U-Pb TIMS data obtained on zircon from the Kartojärvi granite A502.

32 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

data-point error ellipses are 2s 0.60 A416 Kunnasenvaara Sodankylä gneiss

0.56

0.52 2680 U 2640 238 2600

Pb/ 2560

206 0.48 2520 2480 2440 2400 2360 0.44 Concordia Age = 2494 ± 6 Ma n=14/16 (LA-ICPMS)

0.40 9 10 11 12 13 207Pb/235U

Fig. 44. Concordia plot of U-Pb zircon data by LA-SC-ICPMS obtained from the Kunnasenvaara gneiss A416.

Support for the ages of ca. 2.5 Ga from the Vuotso from the Kunnasenvaara gneiss A416 in Sodankylä. complex have recently been obtained by Huhma et These data provide a Concordia age of 2494±6 Ma al. (2018), who reported such ages for three samples (Appendix 1, Fig. 44). From this sample one dis- further south in Sodankylä (A157, A206 and A1671). cordant TIMS analysis with an 207Pb/206Pb age We can add one more sample to this group after of 2.45 Ga was reported by Manninen et al. (2001). recent U-Pb zircon analyses by laser-SC-ICP-MS

33 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

9 SM-ND RESULTS

The Sm-Nd analyses to estimate the average crus- is close to the age of enderbites in the granulite tal residence ages have been available since 1980’s. belt and the Proterozoic igneous rocks east of the Results from the Lapland-Kola Province suggest granulites. In figure 45 the data within each rock significant Paleoproterozoic contributions in rocks association are set in degreasing order of initial outside the Archaean Inarijärvi complex (Bernard- epsilon values. It becomes evident that much of the Griffiths et al. 1984, Huhma & Meriläinen 1991, Proterozoic crust east of the granulites is character- Huhma 1996, 2016, Huhma et al. 2011, Barling et al. ised by clearly positive epsilon-values approaching 1997, Daly et al. 2001, 2006). Some results on rocks the composition of coeval depleted mantle. and garnet concentrates within the granulite belt The diagram also shows a major distinc- were reported by Tuisku & Huhma (2006, 2012) but tion between the Archaean Inarijärvi Complex most data produced by GTK have remained unpub- and the Lapland Granulite belt, where a major lished until now. Paleoproterozoic contribution is evident. The results The Sm-Nd data on ca. 80 samples including iso- are also shown in the conventional epsilon vs. age tope diagrams are given in Appendix 5. In the table diagram (Fig. 52) and map (Fig. 46). The data in and diagram (Fig. 45) the initial epsilon-Nd values other papers cited above are consistent with these were calculated using an age of 1920 Ma, which results.

6 Depleted Mantle ->

2

-2 Juvenile 1.93 Ga crust orthogneisses -6 paragneisses

-10

Archaean gneisses -14 east west

Fig. 45. Epsilon-Nd (1920) for whole rock samples from the Lapland-Kola Province in Finland. The “west” of the Archaean gneisses refers to the “Kevo window” (Luukas et al. 2017). The reference value for depleted mantle is that used in the DePaolo (1981) model.

34 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

Inari complex

Fig. 46. Geological map showing epsilon-Nd (1900) in five categories: largest symbols €-Nd>+0.6, smallest symbol (dot) €-Nd<-7.9.

10 PB-PB RESULTS

During the period of active research in the 1970s the 2.6 Ga (primary age). Individual K-feldspar whole Pb-Pb isotope method was widely used to determine rock pairs give ages of ca. 1.9 Ga. These results, constraints on the age and genesis of various rocks as already discussed by Huhma (1996), suggest a in the Lapland-Kola Province. Some information strong 1.9 Ga thermal influence on the Archaean was provided by Meriläinen (1976) but no data was crust. published until now (Appendix 6). The Pb isotope analyses on whole rocks and The Pb isotope data suggested that the whole K-feldspar of the “1.93 Ga” rocks in the Inari- rock Pb age on the Archaean gneisses is ca. 2.6 Utsjoki area east of the granulite belt (Kuorboaivi Ga, whereas K-feldspars in these rocks register belt in Meriläinen 1976) yield an age estimate of 1.95 Paleoproterozoic lead isotopic compositions (Fig. ± 0.08 Ga (Fig. 48). The initial Pb isotopic compo- 47). The K-feldspar analyses provide a trend on the sition is clearly distinct from the results obtained Pb-Pb diagram with a slope of 0.301. If T2 is set from the K-feldspar of Lapland granulite belt rocks at 1.9 Ga (age of resetting) the slope yields a T1 of (Fig. 48), suggesting a relatively low-µ source.

35 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

Archaean granitoids/ Inarijärvi complex A272 wr-kspar kspar slope 0.301 Age = 1902 ± 49 Ma 16.2 T1=2.6 Ga T2=1.9 Ga A207 (A115 excl.) A115 kspar A270 A207 wr-kspar 15.8 Age = 1946 ± 140 Ma

Pb A272 kspar 0 A270 wr-kspar 800 A212

204 A167 kspar Age = 1838 ± 250 Ma A227 A113 A270 kspar 15.4 1600 A212 wr-kspar Pb/ A207 kspar A212 kspar Age = 1840 ± 310 Ma A227 kspar

207 A115 A113 kspar A213 A213 kspar A226 A113 wr-kspar 15.0 2400 A539 Age = 2013 ± 270 Ma A538 whole rocks A538 kspar Age = 2470 ± 210 Ma A226 kspar A226, A538, A539 A539 kspar MSWD = 8.2 n=10 wr-kspar age ca. 2.6 Ga 14.6 13 15 17 19 21 23 206Pb/204Pb

Fig. 47. The Pb-Pb isotope results from the Archaean Inarijärvi complex. The terrestrial lead isotope evolution curve by Stacey & Kramers (1975) is also shown. (+: whole rock; triangle: K-feldspar)

16.0 "Inari juvenile 1.93 Ga crust" Age = 1945±75 Ma 15.8 MSWD = 0.75 n=11

0 400 A39 15.6 A211

Pb 800

204 1200 A544

Pb/ 15.4 A117 1600 A208 207 A112 A529 15.2 2000 A225 kspar A39kspar x: Lapland granulite A531 A112kspar A211kspar orthogn /kspar A528 15.0 2400 +: Lapland granulite grt-crd-gn/ kspar

14.8 13 15 17 19 21 206Pb/204Pb

Fig. 48. The Pb-Pb isotope results from the Paleoproterozoic rocks E-NE from granulites (diamond), Lapland granulite belt (only K-feldspar), Vaskojoki anorthosite (o) and Pailovaara appinite (A225 K-feldspar, triangle). The terrestrial lead isotope evolution curve by Stacey & Kramers (1975) is also shown.

36 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

11 CONCLUDING REMARKS

This paper reports on the abundant isotopic data from whole rocks and K-felspar and U-Pb ages available for the Lapland-Kola Province in Finland. on titanite the Archean rocks show strong 1.9 Ga The U-Pb data on zircon include old U-Pb TIMS metamorphic effects. analyses from nearly 70 samples together with – 2.5 Ga rocks occur in two belts, the Vuotso com- more recent ICP-MS spot analyses on 20 samples. plex S-SW of the granulites continuing further The old Pb-Pb TIMS data are presented from ca. south to the Koitelainen area, and the western 50 whole rocks and 30 K-feldspar separates. The border zone of the Archaean Inarijärvi complex. previously unpublished Sm-Nd data produced at – Lapland-Kola Province east of the granulites GTK consist of ca. 60 analyses. These data together contains a significant amount of 1.94-1.91 Ga with the results from various published papers (e.g. juvenile crust with arc affinities (Fig. 52). Meriläinen 1976, Bernard-Griffiths et al. 1984, – Lapland granulite belt is characterised by mig- Barbey et al. 1984, Daly et al. 2001, 2006, Tuisku matitic metasediments, 1.91-1.93 Ga enderbites & Huhma 2006 and Tuisku et al. 2012) provide the and 1.904 Ga appinites. The metasediments were basis for our understanding of the geological evolu- derived from 1.94-2.9 Ga sources and contain tion of the Lapland-Kola Province. The age results 1.91 Ga monazites (Fig. 50) and slightly younger are summarised in Table 1 (and with more details metamorphic zircon concurrent with the closure in Appendix 7) and shown in Figures 49 and 50. of Sm-Nd system in garnet. The main results include: The appinites are undeformed and set the lower – Archean gneisses occur in the Inarijärvi complex age limit to the deformation of the granulite belt. and Kevo window. Based on Pb-Pb isotope data

box heights are 2s U-Pb zircon ages 2800 A0227 A0576 A0167 A0213 Inarijärvi

2700 Archean complex A0226 Vuotso complex

Age (Ma) 2600 A0207 A0212 A0113 A0372 A0157 A0115 A0206 A0270 A1671 A0416

2500 A0504

2400

Fig. 49. The U-Pb zircon ages from the Archaean Inarijärvi complex and the ca. 2.5 Ga rocks in the Vuotso complex and the western border zone of the Inarijärvi complex (A207, A212, A270).

37 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

box heights are 2s U-Pb zircon ages 1960 Inari Proterozoic A0459 A0463 Lapland granulite

A0211 igneous rocks 1940 A0458 A0209 A1023 A0241 59833 A0601 A0737Vaskojoki 96558 A1682 A1683 A0208 A0111 A1681 A0451

Age (Ma) 1920 A0457 96562 A0462 A1509 A1957 A0225 A0503 93130 A0455 A0112 1900

1880

Fig. 50. The U-Pb zircon ages from the Proterozoic igneous rocks in the Lapland-Kola province (left: Silisjoki and Luossavarri suites, right: Lapland granulite complex).

box heights are 2s 1930 U-Pb ages on monazite from Lapland granulite complex 1920 A0276 A0317 A0318 1910 A1504 A0087 A0171 A0214 A0088 A1505 A0268c A1786 1900 A0316 A0269 A0419 Mean = 1906.6±3.0 [0.16%] 95% conf. Wtd by data-pt errs only, 0 of 15 rej.

1890 A0268e MSWD = 6.7, probability = 0.000 (error bars are 2s)

1880

Fig. 51. The U-Pb ages on monazite from the Lapland granulite complex.

38 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

DM (DePaolo) Inari Proterozoic (diamond) 4 Lapland granulite igneous (x) A416

A213 A227 A504 0 A157 A212 A167 Vaskojoki anorthosite A207 Nd -

-4 Epsilon

-8 A502

-12 1800 2000 2200 2400 2600 2800 Age (Ma)

Fig. 52. Epsilon-Nd vs. age diagram for whole rock samples from the Lapland-Kola Province in Finland. Evolution lines are shown for supracrustal granulites and Archean gneisses of unknown age. DM is the evolution line of depleted mantle (DePaolo 1981).

ACKNOWLEDGEMENTS

Olavi Kouvo is fondly acknowledged here as the Marker, Tapani Mutanen and Reino Kesola are also father of isotope research in Finland. His impact acknowledged. I am also personally grateful for the on the current topic, together with that of the per- co-operation of and discussions with numerous sonnel at the GTK isotope laboratory, has been geologists along the way, particularly with Raimo enormous. In addition to the old samples obtained Lahtinen, Jarmo Kohonen and Jouni Vuollo. Tom by Meriläinen and his group, the samples with Andersen is acknowledged for providing the pro- significant geological impact provided by Mogens gram used for MC-ICPMS data reduction.

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0,9 -0,9 1,9 -1,5 -1,4 3,0 0,3 -1,0 3,4 2,4 -1,2 2,5 2,7 -1,4 -1,5 Eps-Nd (Age) discordant discordant & sl. heterogeneous Ti rev discordant ca. 1.96 Ga? very discordant Ti nearly concordant ca. 2.19 Ga? Ti 1997±23 Ma, TIMS zr disc 2504±6 Ma Ti 1870±20 Ma, TIMS Zr disc ca. 2.45 Ga Ti disc ca. 1.9 Ga, TIMS Zr 2.46 Ga discordant Ti 1898±10 Ma TIMS heter. disc 207Pb/206Pb ca. 2.3 Ga Huhma et al. 2018 TIMS: Disc. Ti ca. 2.15 Ga, disc; Zr 2.45 Ga TIMS discordant Intercepts ca. 2.4 & 0.5 Ga Huhma et al. 2018, TIMS ca. 2.49 Ga Huhma et al. 2018, TIMS heter Archean TIMS 1946±5 Ma CA-TIMS concordant 1.94 Ga TIMS discordant 1.93Ga? TIMS very discordant (c. 1.9 Ga?) TIMS very discordant (1.9 Ga?) TIMS very disc; CA-TIMS rev disc 1.93 Ga? TIMS discordant ca. 1.93 Ga ICPMS range 1.87-2.43 Ga, TIMS disc; >2.2 Ga Ti 1903±10 Ma very discordant zr archaean? Ti ca. 1.89 Ga Zr Archean, Mz 2472±2 Ma, Sm-Nd grt 1827±9 Ma very discordant Archean? very discordant 7/6 ages 2.2.-2.3 Ga Comments I? I? I? C C C C C C C C C C I I I C I? I C C C C C C R 27 35 34 9 10 8 6 5 6 26 16 7 8 10 19 10 8 35 27 8 5 6 5 6 5 ±2s 2744 2709 2603 2520 2504 2482 2506 2505 1929 1928 1926 1925 1920 1917 2760 2737 2524 2493 2486 2509 2501 2494 1944 1943 1925 Age (Ma) TIMS TIMS TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS-CA ICPMS., TIMS TIMS TIMS TIMS TIMS SIMS, TIMS Attom, TIMS TIMS TIMS ICPMS, TIMS ICPMS, TIMS Attom, TIMS ICPMS, TIMS ICPMS, TIMS-CA ICPMS, TIMS TIMS TIMS Method Gneiss (granite) Granodiorite (gneissose) Granite (porphyritic) Tonalite Granodiorite Granite Gneiss (volcanic) Volcanic breccia Diorite (quartz) Tonalite Trondhjemite Gneiss ( quartz dioritic) Anorthosite Anorthosite Tonalite Diorite (quartz) Migmatite (neosome) Gneiss (mica-) Granite (porphyritic) Granite (porphyritic) Granodiorite Gneiss (arkosic) Gneiss Gneiss Diorite (quartz) Diorite (quartz) Gabbro (dioritic) Granite Granite Rock type Käräjäsaari Inari Kittilompolo Utsjoki Pirivaara Inari Akulahti Inari Partakko Inari Lemmekäspalo Inari Kaiunismännikkö Sodankylä Sadinoja Sodankylä Mieraslompolo Keniskoski Nuottalvaara Keinodakoaivi Utsjoki Vaddejärvi Inari Närrijärvi Inari Kuorpasaari Inari Turvejärvi Neiden Norway Neiden Norway Porttipahta Sodankylä Kunnasenvaara Sodankylä Vetsikko Utsjoki Luossajauri Utsjoki Suovavaara Inari Savuslammet, Inari Roavvi Tievja Pennasnjarga Inari Kuktshvaara Isokivennotko Utsjoki Iso-Roiro Inari Location A0576 A0213 A0226 A0212 A0270 A0504 A0157 A0206 A0458 A0112 A0211 A0209 A0737 A0601 A0167 A0272 A0113 A0115 A1671 A0416 A0459 A1023 Table 1. Lapland-Kola summary, ages U-Pb zircon (for more details see Appendix 7). Sample A0227 A1845 2.52-2.48 Ga, Inarijärvi complex A0207 2.52-2.48 Ga, Vuotso complex A0372 1.94-1.91 Ga Inari A0463 A1024 A1113 Archean Inarijärvi complex

42 Geological Survey of Finland, Open File Research Report 37/2019 Isotope results from Lapland-Kola province in Finland

1,7 2,2 1,8 -1,4 1,0 1,9 -1,0 0,4 0,2 0,9 1,7 1,1 -0,5 -2,6 -1,1 0,1 -0,4 Eps-Nd (Age) TIMS discordant TIMS discordant 7/6-age 1.88 Ga TIMS very discordant 1.9 Ga? TIMS disc, upper intercept 1911±6 Ma TIMS very discordant 1.9 Ga? very discordant (c. 1.9 Ga?) very discordant, compatible with 1.9 Ga ca. 1.9 Ga sl. discordant, 207/206 age 1.9 Ga TIMS discordant (c. 1.9 Ga?) Borax fusion analysis concordant! also NORDSIM 2005, Tuisku & Huhma 2006 also NORDSIM 2005, Tuisku & Huhma 2006 also NORDSIM 2005, Tuisku & Huhma 2006 borax fusion analysis Tuisku et al. 2012 Mz ca. 1.92 Ga, large error? Zr slightly disc coeval? Tuisku & Huhma 2006, Zr-sims: 1.9-2.1 Ga gems 1905 Ma, also older heter. discordant UI ca. 1.9 Ga (Palloaivi appinite?) Palloaivi appinite? discordant, age 1901+-5 combined with A456 discordant 1.9 Ga? Mz 1900±10 Ma, zr discordant ca. coeval? Tuisku et al. 2012, Mz 1900±7 Ma, Zr heter Mz 1898±6 Ma, disc Zr coeval? Mz 1909±5 Ma, Zr disc., 7/6-age 1.96 Ga Mz 1903±3 Ma discordant 7/6 age ca. 1.9 Ga (location?) discordant 7/6 ca. 1.9 Ga Comments C C C C NC C C C C? C I? NC NC I? I? C C C C R 7 6 10 8 3 3 8 5 5 2 9 6 6 5 10 14 5 9 4 ±2s 1915 1906 1897 1897 1921 1919 1919 1917 1909 1905 1904 1904 1904 1901 1916 1913 1923 1915 1906 Age (Ma) ICPMS, TIMS ICPMS, TIMS ICPMS, TIMS TIMS ICPMS, TIMS TIMS, SIMS TIMS, SIMS TIMS, SIMS TIMS TIMS TIMS TIMS TIMS TIMS-CA TIMS TIMS TIMS ICPMS, TIMS TIMS TIMS TIMS TIMS SIMS, TIMS SIMS TIMS TIMS TIMS, SIMS TIMS TIMS TIMS TIMS Method Diorite (quartz) Diorite (quartz-, meta-) Granitoid (porphyritic) Diorite (quartz) Tonalite Enderbite Enderbite Enderbite Gneiss (hypersthene-) Granite (dyke) Diorite (appinite) Granite (appinite?) Diorite (appinite) Gabbro (appinite) Diabase Granite (anatectic vein) Diorite (spotted, meta-) Gneiss (granitic-) Gabbro (pegmatite) Gneiss (quartz-feldspar) Diorite (quartz) Diorite Diorite (quartz) Norite Diabase Granite (anatectic vein) Tonalite Granite Granite Gneiss (hypersthene-) Diorite (quartz) Rock type Roullekuoddetsohkka Isoköngäs Utsjoki Vetsikko Utsjoki Sirma Norway Syysjärvi Inari Pktervarsavu, Utsjoki Köysivaara Inari Vuijeminhaara, Inari Vellivaara Inari Mutusjärvi Inari Pielpajärvi Inari Vuoskuljärvi Pailovaara Inari Suhuvaara Inari Mutusjärvi Inari Solojärvi Inari Polmak Utsjoki Utsjoki Uhtsaskaidas Utsjoki Sarmijärvi Inari Kenttäsaaret Inari Sotajoki Inari Akulahti Inari Kaarle Kustaan Kaivos Mutusjärvi Inari Korppikuru Myösäjärvi Koppelo Appisjoki Inari Ndrenes Norja Karnasrattaoaivi Location A0208 96562 93130 A0116 A0117 A1683 A1681 A1682 A0451 A0457 A0503 A0462 A0225 A1957 A0455 A0419 Sample 96558 59833 A0954 A0170 A0039 Lapland granulite complex, igneous rocks A0241 A0111 A1509 A0456 A0316 A0269 A0171 A1786 A0461 A0228 1.94-1.91 Ga Inari Table 1. Cont.

43 Geological Survey of Finland, Open File Research Report 37/2019 Hannu Huhma

0,6 -8,2 -2,3 -2,0 -2,0 -2,4 -1,5 -3,6 -2,1 -2,2 Eps-Nd (Age) TIMS upper intercept ca. 1.92 Ga discordant range of ages, Ti= 1904+-20 Ma sl. discordant 7/6-age 1.92 Ga Mz 1909±3 Ma, Zr 1914-2020 Ma GEM Zr 1902±3 Ma, Mz 1906±2 Ma Mz 1890±5 Ma T&H 2006:1.9-2.5 Ga, Mz 1.91Ga, Grt 1.88Ga T&H 2006:1.87-2 Ga, Grt 1886±6 Ma heter, partly disc. Pb/Pb up to 2043 Ma heter: Pb/Pb 1905-2076 Ma, GEMS 1.92 Ga Mz 1915±3 Ma, Zr discordant 7/6 ca. 2 Ga Mz 1913±11 Ma, Zr >2 Ga Mz 1913±9 Ma, Zr heter > 2 Ga Mz 1906±7 Ma, 2 zr anal. > Ga Mz 1907±7 Ma sl disc T&H 2006: 1.87-2.4 Ga; Grt 1888±6 Ma T&H 2006: 1.92-2.47 Ga T&H 2006: 1.9-2.1 Ga; Mz 1906±5 Ma Age on titanite, Kortman’s sample, abundant large titanite Comments I? C C C C I? C R 22 17 8 11 10 ±2s 1885 1882 1891 1913 1907 Age (Ma) TIMS ICPMS, TIMS TIMS TIMS TIMS ICPMS, TIMS SIMS, TIMS TIMS TIMS TIMS TIMS TIMS SIMS, TIMS SIMS TIMS TIMS SIMS, TIMS TIMS SIMS, TIMS TIMS Method Granite (pegmatite) Granite Granite (anatectic vein) Tonalite Gneiss (garnet-cordierite) Tonalite Granulite (leucosome) Diorite (quartz) Gneiss (garnet-cordierite) Granulite (cordierite) Gneiss (garnet-cordierite) Granulite (paragn) Granulite (melanosome) Granulite (paleosome) Tonalite Granite (anatectic vein) Granulite (leucosome) Diorite (quartz) Granulite (melanosome) Gneiss Rock type Kartojärvi Inari Kahvijänkä Inari Pääsaari Inari Koskivuono Inari Viekkala Maunuvaara Inari Kaarle Kustaan Kaivos Jurmukoski Inari Kiellajoki Könkäänjärvi Inari Törmänen Inari Paukkula Inari Kaarle Kustaan Kaivos Kuttura Inari Nuoransuunselkä Inari Törmänen Inari Kuttura Inari Lammaspää Inari Kuttura Inari Marastoäytsi Inari Location A0502 A0397 A0166 Sample A0087 Lapland granulite complex, paragneisses (epsilon-Nd at 1.92 Ga) A0276 SW from granulite complex A0224 column Method: TIMS-CA = chemical abrasion treatment & TIMS, ICPMS multicollector ICPMS, Attom single collector column R-reliability: I= upper intercept, C=concordant analysis, NC= “nearly” concordant ?= problematic column Comments: Ti=titanite, Mz=monazite, Zr=zircon, Grt=garnet, disc=discordant, T&H 2006= Tuisku&Huhma 2006 column Eps-Nd(Age): calculated initial Nd epsilon using age in Age or 1.92 Ga A1507 A0204 A0317 A0318 A0268c A0214 A1508 A1506 A0088 A0268e A1504 A0203 A1505 A0156 Lapland granulite complex, igneous rocks Table 1. Cont.

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