sign in sign up
<<
Home , Blefjell, Geology of Norway, Gothian orogeny

NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in , South 57

Provenance and correlation of sediments in Telemark, South Norway: status of the Lifjell Group and implications for early Sveconorwegian fault tectonics

Jarkko Lamminen

Lamminen, J: Provenance and correlation of sediments in Telemark, South Norway: status of the Lifjell Group and implications for early Sveconor- wegian fault tectonics. Norsk Geologisk Tidsskrift, Vol 91, pp. 57-75. Trondheim 2011, ISSN 029-196X.

The Telemark Supracrustals are a thick, well preserved, greenschist facies, sediment and volcanic sequence exposed in the Telemark area in South Norway. From 1500 to 1347 Ma intracontinental rifting, followed by a long period of tectonic quiescence left a bimodal volcanic sequence, the Rjukan Group, overlain by a mainly quartzitic sedimentary succession, the Vindeggen Group. From c.1170 to 1000 Ma, a dynamic, probably largely strike-slip, tectonic regime leading to the Sveconorwegian resulted in the deposition of laterally discontinuous groups of sediments, commonly conglomeratic, and bimodal volcanic to sub-volcanic magmatic rocks above a major , called the Sub- svinsaga unconformity. Here, we report detrital zircon U-Pb data from three units that have been alternatively placed below and above this unconformity. The Lifjell Group was regarded as correlative to the Vindeggen Group by J.A. Dons, as part of his classical Seljord Group (now obsolete). Then it was reassigned to a much higher level, overlying the 1155 ± 2 Ma Brunkeberg porphyry. It includes prominent c. 1780 and 1500 Ma detrital zircon age modes and lacks any zircons younger than 1350 Ma. the age distribution is similar to the Brattefjell Formation in the Vindeg- gen Group, supporting the original correlation between these units. Another set of samples was taken from an elongated sandstone-conglomerate unit near Høydalsmo. Detrital zircon shows typical Palaeoproterozoic and c.1500 Ma ages, but 1300-1200 Ma and c.1130 Ma ages are also abundant. This unit is coeval with the Eidsborg Formation and confirms for the first time that the Eidsborg Formation is separated from underlying deposits by an angular unconformity. Depositional contacts with the Rjukan, Oftefjell and Høydalsmo groups indicate that the Eidsborg Formation once covered large areas in Telemark, and that all the earlier formations were already exposed to erosion. A survey of different conglomerates in the Sve- conorwegian succession in Telemark reveals a trend from quartzite clasts in the oldest Svinsaga conglomerates to polymictic conglomerates in the younger formations and a general lack of granitic clasts until the very uppermost parts of the succession. This can be explained by exhumation of a thick quartzite cover and repeated burial, uplift and recycling of earlier deposits, until the basement was exposed. The activity of basin-bordering faults is clearly demonstrated by the changing conglomerate clast lithologies. The Sveconorwegian succession in Telemark was probably deposited in a strike-slip tectonic environment. The stratigraphic status of the Lifjell Group still remains enigmatic, but most likely it is part of the Vindeggen Group.

Jarkko Lamminen ([email protected]), Department of Geosciences, University of Oslo,P.O. box 1047 Blindern, N-0316 Oslo, Norway.

Introduction 2010). The geochronology of the magmatic rocks was established by Dahlgren et al. (1990a, 1990b), Laajoki et U-Pb age determination of allochthonous basement The al. (2002), Bingen et al. (2003, 2005) and Andersen et al. Telemark Supracrustals are exposed in the Telemark area (2007). In recent years, new detailed mapping of the area in South Norway. They consist of volcanic and sedimen- lead to a significant improvement of our understanding tary rocks that partly preserve their original stratigraphic of the lithostratigraphy and of the supra- relationships. They were faulted, folded and metamor- crustal rocks (Andersen et al. 2004a; Laajoki 2002a,b, phosed under greenschist facies conditions, and con- 2005, 2006a, 2006b; Laajoki & Lamminen 2006; Laajoki trast with the high-grade gneisses that dominate the rest & Corfu 2007, 2008; Köykkä & Laajoki 2009; Köykkä of the Southwest Scandinavian Domain. Their genesis 2010; Lamminen & Köykkä 2010). and stratigraphy have been studied for more than 200 years (e.g. Törnebohm 1889; Werenskiold 1910; Bugge The rocks in Telemark have archived almost 500 mil- 1931; Wyckoff 1934). The whole area was mapped by J.A. lion years of geological history. They occupy a unique Dons (Dons 1959, 1960a, 1960b, 1962, 1972), who estab- time interval between two , the Gothian Orog- lished a tri-partite stratigraphy consisting of the Rjukan, eny (c.1650-1520 Ma) and the Seljord and Bandak groups, from bottom to top. Over (c.1140-900 Ma). During this large time span, the style of the years the area was studied geochemically (Menuge tectonism changed from simple rifting via tectonic quies- & Brewer 1996; Brewer & Menuge 1998; Knudsen et al. cence to a more complex and dynamic behaviour before 1997; de Haas et al. 1999; Andersen et al. 2002; Köykkä the Sveconorwegian Orogeny. The original stratigraphic 58 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY scheme for Telemark, established by J.A. Dons, survived rocks with minor mafic additions (Högdahl et al. 2004). for 40 years until a new scheme was informally proposed The exact duration or geographical extent of the TIB by Laajoki et al. (2002), based on fieldwork and geochro- magmatism is not known because a large part of the plu- nological data. Problems still exist with this scheme and tonic belt is covered by Caledonian nappes. some of these are highlighted in this study. The Eastern Segment is the easternmost crustal block The early Sveconorwegian deposits in Telemark are char- of the SSD connected to the TIB along a fault contact acterised by abundant conglomerates that indicate high (the Protogine Zone). It consists of reworked TIB rocks. relief and the presence of fault-bounded depositional Sveconorwegian, c.970 Ma high-pressure granulites and basins. Defining individual basins is difficult in highly facies is recorded in the Eastern deformed supracrustal successions, but field observations Segment (Johansson et al. 2001). Other crustal blocks show that the early Sveconorwegian basins in Telemark west from the Eastern Segment are called Sveconorwe- probably were small, intermontane pull-apart basins. gian (Stephens et al. 1996). They are bor- This study presents new detrital zircon U-Pb data from dered by the “ Zone”, a Sveconorwegian oblique some early Sveconorwegian sedimentary units in Tele- thrust zone (Viola & Henderson 2010). The first alloch- mark. The objective is to test parts of the new lithostrati- thonous block westwards is the Idefjorden Block. It con- graphic scheme by Laajoki et al. (2002), addressing the sists of diverse calc-alkaline volcanic and plutonic rocks problematic status of the Lifjell Group and the uncon- and sedimentary rocks developed in settings formable status of the Eidsborg Formation. The data for and accreted to the Fennoscandian Shield during the individual samples are compiled in appendix 1 and 2 in (i.e. c.1720-1520 Ma, Åhäll & Connelly the electronic supplement that accompanies this article. 2008).

Westwards, the Bamble-Lillesand and -Mar- Geological setting and regional strand blocks are thought to have been connected orig- lithostratigraphy­ inally but are now separated by the Oslo (Starmer 1996). These two blocks structurally over- lie other blocks to the west in the SSD. The Bamble- The Fennoscandian Shield is composed of an Archaean Lillesand Block consists of paragneisses and orthog- core in the northeast and progressively younger Protero- neisses, gabbros and quartzites (Starmer 1993; Padget & zoic crustal domains towards the southwest. Summaries Brekke 1996). The Bamble-Lillesand Block may be com- of the regional Precambrian geology are given by Gaál & posed of two lithotectonic : the mainland Bam- Gorbatschev (1987), Gorbatschev & Bogdanova (1993) ble area with a pre-Sveconorwegian crustal history, and and Bogdanova et al. (2008), and a map of the entire a Sveconorwegian island arc fragment along the cen- shield has been published by Koistinen et al. (2001). The tral part of the coast (Tromøy and adjacent islands) area including southwest Sweden and southwest Nor- (Andersen et al. 2004b). The Bamble-Lillesand Block is way is the youngest part of the Shield and has been called separated from the Telemark Block (see below) by the The Southwest Scandinavian Domain (SSD, Gaál & Gor- Sveconorwegian Porsgrunn-Kristiansand Shear Zone batschev 1987), the Sveconorwegian Belt (Bingen et al. (Fig. 1), along which upper amphibolite-facies to gran- 2008) or the Sveconorwegian orogen (e.g. Corfu & Laa- ulite facies gneisses and metasediments of the Bamble- joki 2008). We choose to use the first of these names. The Lillesand Block (Nidelva and Kragerø complexes) have area is structurally complex, including several Precam- been thrust over the amphibolite-facies granitic gneisses brian fault- and shear zones that strike in a general N-S of the Telemark Block (Starmer 1993). The Kongsberg- direction and that subdivide the area into several struc- Marstrand Block consists mainly of 1700-1500 Ma calc- tural domains (Fig. 1). In the literature, the Precambrian alkaline meta-igneous rocks and coeval metasediment­ bedrock areas bordered by these fault and shear zones ary rocks (Modum Complex), and younger intrusions. have been called sectors, terranes and blocks. A non- genetic block-terminology (Andersen 2005a) is used The rest of the SSD further to the west in southwest here. Norway­ comprises the Telemark and the Hardanger- vidda-Rogaland blocks. The Mandal-Ustaoset Shear The Southwest Scandinavian Domain (SSD) Zone (Sigmond 1985) separates the two blocks, but they are generally considered to be genetically simi- The SSD is bordered in the east by the c.1400 km long, lar. Bingen et al. (2005) coined the term “Telemarkia” 1850-1650 Ma Transscandinavian Igneous Belt (TIB), to pool these two blocks together. The Telemark Block consisting mainly of alkali-calcic granitoids and their is the focus of this study. It consists of a well preserved volcanic equivalents, as well as minor mafic rocks. The volcanic­-sedimentary suite in the north, called the Tele- TIB is interpreted as a continental magmatic arc, which mark Supracrustals, and gneisses in the south, called the developed along the NNW-SSE running central axis Vrådal gneiss complex. The Hardangervidda-Rogaland of the present day Fennoscandian Shield. The magmas Block consists mostly of orthogneisses and granites with of TIB rocks formed by re-melting older Svecofennian some supracrustal rocks. These are Mesoproterozoic and NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 59

Figure 1. Geological map of central Telemark. The study areas are framed. Stratigraphic scheme follows Laajoki et al. (2002). Dashed lines are .

include the sedimentary Hettefjorden and Festningsnu- lower succession deposited between c.1510-1347 Ma, tan groups and the volcano-sedimentary Sæsvatn-Valldal referred to as the “Vestfjorddalen Supergroup” by Laa- sequences (Bingen et al. 2002). They are potentially cor- joki & Lamminen (2004), and one overlying succes- relative to the Telemark supracrustal rocks (Torske 1985; sion, deposited between c.1170-1010 Ma and separated Bingen et al. 2002; Lamminen & Köykkä 2010). by a major unconformity (sub-Svinsaga unconformity, Dons 2004; Laajoki 2000, 2003, 2009). This Sveconorwe- The Telemark Supracrustals gian succession corresponds to the Bandak Group in the old stratigraphic scheme. Its type area around Lake Ban- A suite of well-preserved, Mesoproterozoic volcanic and dak was probably the site of a basin, which is referred to sedimentary rocks, called the ‘Telemark Supracrustals’, below as the “Bandak rift basin”. Another depocentre was form a prominent feature in the Telemark Block (Dons located in the northeast, where the Heddal Group was 1960a, b, 2004; Sigmond et al. 1997; Laajoki 2000, 2003; deposited in a separate basin, “the Heddal basin”. Laajoki et al. 2002; Bingen et al. 2001, 2005). They form a supracrustal succession approximately 10 km thick, The Rjukan rift basin metamorphosed under low-grade greenschist-amphibo- lite facies (Brewer & Atkin 1987; Atkin & Brewer 1990). The Vestfjorddalen Supergroup (the Rjukan rift basin) Dons (1960a) divided the Telemark supracrustal rocks starts with the Rjukan Group (Fig. 1). No depositional into three groups: Rjukan (oldest), Seljord and Ban- basement for the Rjukan Group has been clearly iden- dak (youngest), separated by major unconformities. The tified in the field. The group consists of the Tuddal For- Heddal Group was introduced by Dahlgren et al. (1990a) mation, made up of c.1.51 Ga continental felsic volcanic for correlative rock unit of the Bandak Group in the east- rocks (Dahlgren et al. 1990a; Nordgulen 1999; Bingen et ern part of the Telemark Block. Laajoki et al. (2002) pro- al. 2005), overlain by a c.2 km thick succession of the vol- posed to abandon the original tri-partite division, keep- canic-sedimentary Vemork Formation (c. ≤1495 ±2 Ma, ing only the Rjukan Group, following new radiometric Laajoki & Corfu 2007), characterised mainly by mafic dating results and the uncovering of several unconfor- volcanism (Fig. 1). The stratigraphic relations between mities. Especially important is the dating of the Brunke- the Tuddal and the Vemork formations has been a mat- berg porphyry at 1155 ± 2 Ma (Laajoki et al. 2002) and ter of debate (cf. Dahlgren et al. 1990a; Dahlgren & Hea- its interpretation. Today, the Telemark supracrustal rocks man 1991; Brewer & Menuge 1998; Laajoki & Corfu 2007; have been shown to consist of two main successions, a Köykkä 2010). In this work, the traditional interpretation 60 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY is followed, where the Vemork Formation is part of the under the Eidsborg Formation. The Heddal Group in the Rjukan Group (see Laajoki et al. 2002). The Rjukan Group northeast and the Kalhovd Formation in the northwest is overlain unconformably by the c.7 km thick sedimen- (Bingen­ et al. 2003) are probably correlative to the Eids- tary-dominated Vindeggen Group (Fig. 1). The Vindeg- borg Formation.­ gen Group consists of several sandstone and mudstone formations deposited in various environments includ- The Lifjell Group ing alluvial, tidal flat and open marine. The group is com- plexly faulted into several internally folded blocks (Fig. 1). The Lifjell Group was introduced by Laajoki et al. For this reason, individual formations within the group are (2002) to describe a wedge-shaped quartzite unit east discontinuous and may be missing in some areas. The true of the town of Seljord (Figs. 1 and 2), originally part of thickness of the Vindeggen Group is unknown because it Dons’ Seljord Group (Dons 1960a). It was defined on is abruptly cut by the sub-Svinsaga unconformity. the basis of mapping and U-Pb zircon dating. Mapping of the quartzites southeast of Seljord revealed that they The Bandak rift basin overlie felsic volcanic rocks assigned to the Brunkeberg Formation­ (Fig. 2). The Brunkeberg Formation was orig- The c.2000 m thick Sveconorwegian succession, defining ­ inally correlated with the Rjukan Group. This placed the the Bandak rift basin, corresponds to the Bandak­ overlying rock unit as correlative with the Seljord Group. Group, sensu Dons 1960a. An angular unconform­ However, U-Pb zircon dating of this volcanite at 1155 ± ity (the sub-Svinsaga unconformity; Köykkä & Laajoki 2 Ma by Laajoki et al. (2002) showed that it was much 2009; Laajoki ­2009) separates the Vestfjorddalen Super- younger than the Rjukan Group. This meant that the group from the overlying supracrustal succession, which overlying unit must be significantly younger than the has a depositional­ age that coincides with the early- Seljord Group, and thus it was named the Lifjell Group. middle Sveconorwegian Orogeny (or c.1200-1000 Ma). The remaining part of the Seljord Group was renamed This supracrustal succession is more diverse, consisting the Vindeggen Group. It was also suggested that the tra- of coarse sedimentary rocks interlayered with bimodal ditional name of the Bandak Group be abandoned; two magmatic rocks. On a regional scale, the formations­ new groups, the Høydalsmo and Oftefjell, were intro- are laterally restricted and variable, which suggests duced and the Lifjell Group was correlated with these. that they were laid down in separate basins, or sub- basins (Laajoki­ et al. 2002; Bingen et al. 2003), possibly The Lifjell Group consists of intensively deformed in a trans­tensional tectonic regime (Bingen et al. 2003; quartzites, in places isoclinally folded, and a strongly Lamminen­ et al. 2009; this study). The type area for the deformed conglomerate and sandstone succession in its Sveco­norwegian succession is around Lake Bandak, but basal part, called the Vallar Bru Formation (see below). it correlates with the Heddal Group in the northeast and In the east, it is cut by the Skogsåa porphyry (Laa- the Kalhovd Formation in the northwest (Bingen et al. joki et al. 2002), which is the lowest part of the Heddal 2003). Generally, the oldest Sveconorwegian deposits are Group. In the west, a large fault system runs through volcanic­-sedimentary whereas the youngest formation Seljord­ from NE to SW, and is called the Slåkådalen-­ lacks volcanic rocks. Grunningsdalen fault zone (Fig. 2) (Laajoki 2002a; Laajoki­ 2006b). It forms a valley between the Lifjell The Sveconorwegian succession starts with the Ofte- and the mountains west of it. The fault fjell Group (Fig. 1) (Laajoki 2006a), which is sediment­ zone has a completely­ different geology compared to ary in the basal part and volcanic-sedimentary in the the rocks around it. It includes at least two types of upper part. The Svinsaga Formation lies at the base of conglomerate­ and various quartzites and volcanic rocks the Oftefjell Group, unconformably above theVindeggen including the Brunkeberg ­porphyry. The Seljord con- Group around Lake Bandak in the south. but conform- glomerate (de Haas et al. 1999) forms a distinct lithotype able near mount Gausta in the north. This unconformity in this succes­sion. It was renamed as Vallar Bru conglom- is named the sub-Svinsaga unconformity and includes a erate by Laajoki (1998). In the south the Lifjell Group is heavily brecciated zone (Köykkä & Laajoki 2009; Laajoki bordered by a similar conglomeratic-volcanic lithology. 2009), which probably represents a regolith. It has been The rocks in the western and southern borders are tightly shown that a hiatus of at least 150 m.y. is associated with folded and deformed, and the conglomerates are usually this unconformity (Lamminen et al. 2009). The bulk highlydeformed. The rheologi­cally incompetent quartz- of the Svinsaga Formation is composed of feldspathic ite and volcanite clasts are stretched, while some rare sandstone withsome pebbly units. Above the Svinsaga granite clasts have resisted. Detailed field descriptions of Formation­, the Ofte Formation consists of bimodal vol- the lower contact of the Lifjell Group and the associated canic rocks and coarse, mainly volcaniclastic sediments. conglomerates (including the Vallar Bru Formation) are The Ofte Formation is unconformably overlain by the given in Laajoki (2002a, 2006b). The sedimentological volcanic-sedimentary Høydalsmo Group. The Sveco­ characteristics of the main quartzite of the Lifjell Group norwegian succession ends with the Eidsborg Forma- are in many places masked by intense deformation. How- tion, which consists only of sedimentary rocks. Around ever, in places one can find wave ripples, heterolithic Lake Bandak, no angular unconformity is observed units and tabular cross bedding. The sandstone is also NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 61

Figure 2. Simplified geological map of the Lifjell-Seljord region. Sampling sites are marked. Map is modified from geological maps available at www.ngu.no in 2010.

well sorted. These features suggest a shallow marine ori- of a c.1 km thick succession of mainly feldspathic sand- gin for the main part of the Lifjell Group. The lower part stones with some conglomerates. The sedimentary struc- of the Lifjell Group, the Vallar Bru Formation, is inter- tures are well preserved. At least four different types preted to represent a typical alluvial fan massflow type of conglomerates can be defined (Figs. 4-6), based on conglomerate. Sedimentologically it is in striking con- their clast population. The unit was originally included trast with the shallow marine part of the Lifjell Group. in the Seljord Group (Dons 1962, 1963, 1972), later in the underlying Rjukan Group (Dons 2004), and most The Garvik quartzite recently in the Sveconorwegian Røynstaul Formation (Høydalsmo Group) by Laajoki & Lamminen (2006). At the southern margin of the Telemark Supracrustals, the rocks are highly deformed and divided into thrust sheets. In the west the Snaunetten basin is bounded, from north The pre-rift basement for the Telemark Supracrustals has to south, by the Vemork Formation basalt, Tuddal For- never been identified, but originally it was thought to mation rhyolite and the Oftefjell Group. The contact be the Bø granite in the south (Dons 1960b; Fig. 2). The with the Vemork Formation is unambiguously deposi- gneisses in the Vrådal gneiss complex were studied by tional (Fig. 5a), while the contact with the Tuddal For- Andersen et al. (2007), who obtained an age of 1208 ± 6 mation is not exposed. The contact with the Ofte- Ma for a granitic gneiss in the Kviteseid area. The Bø gran- fjell Group is locally observed to be depositional. For a ite is probably of similar age. The contact between the detailed description of the western contact, see Laajoki supracrustals and the Bø granite is very sharp. A parallel- & Lamminen (2006). The eastern margin is defined by laminated quartzite with numerous amphibolite veins and a major fault called the Raudsinutan fault, which juxta- dykes is the first supracrustal unit that comes in contact poses the basin succession against the of the with the Bø granite in the south. This and similar gneissic Vindeggen Group (Gausta Formation). The Raudsinutan rocks further to the west were collectively named “Trans- fault is interpreted as syn-sedimentary fault due to the taulhøgdi supracrustals” by Laajoki et al. (2002). In the lithology of the conglomerates in the sediments (details newly revised stratigraphic scheme the status of this thin are given later). Later this fault was reactivated, causing quartzite has not been definitively established. Here we right-lateral displacement and folding in the Snaunetten call it informally the Garvik quartzite from the locality basin (insets in Fig. 3). In the north the basin margin is where it is observed close to Lake Seljord. a hook-fold, whereas in the south the sedimentary strata are mostly locally folded and dissected by NW-trending The Snaunetten basin faults.

The Snaunetten basin (Figs. 3-4) is a palaeobasin defined Lithostratigraphic columns of the Snaunetten basin are by a NE-SW oriented, elongated rock body consisting shown in Fig. 4. The variety of conglomerates found is 62 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY

Figure 3. Geological map of the Snaunetten basin region. Insets show detailed mapping in the north and south. Sampling sites are marked in the insets. Basemap after Dons 2004.

Figure 4. Simplified lithostratigraphical columns from northern and southern parts of the Snaunetten basin. The basin is mainly made of sandstone, but contains various conglomerates, probably of alluvial fan origin. The conglomerates vary in composition. Sampling sites are marked. NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 63

Figure 5. The conglomerate varia- bility in the northern Snau­netten basin. For relative stratigraphic­al positions of the conglomerates­, see Fig. 4. UTM coordinates (WGS84/zone 32V) are provided­ in the lower right corners of the pictures. (A) Depositional con- tact of the Snaunetten basin with Vemork Formation basalts. (B) Mass-flow bouldery conglome- rate in the northernmost tip of the Snaunetten basin (Fig. 3b). Clasts are generally c.15 cm in size. Largest quartzite clasts are up to 1.5 m. (C) Polymictic mass- flow conglomerates­ interbed- ded with sheet sandstone. This conglomerate comes on top of the conglomerate­ in Fig. b. Two clusters of larger clasts are seen, which is typical for ephemeral rivers. See compass­ for scale. (D) Very poorly sort­ed conglome- rate consist­ing of basic volcanic and acid volcanic ­clasts. These deposits are associated with large scale sets of tabular cross- beds (eolian?). Size of nameplate is c.15 cm. (E) Conglomerate consist­ing solely of acid volcanic clasts. The apparent orientation ­ of the clasts is tectonic.

shown in Figs. 5-6. Sedimentologically the Snaunetten suggest episodic and unconfined flow. Large scale dunes basin contains conglomerates of probable alluvial fan ori- with pin-stripes could be eolian in origin (Fryberger & gin and monotonous sandstones with very minor mud- Schenk 1988). stones. The conglomerate beds are laterally restricted and occasionally soft-sediment deformation structures can be seen. In the north, the basement of the Vemork Analytical methods Formation is overlain by a polymictic conglomerate con- sisting of poorly sorted boulders up to 1.5 m in size (Fig. Material studied 5b and c). Further to the south the conglomerate is com- prised only of basaltic and acid volcanic clasts (Fig. 5d). Samples analysed in this study are summarised in Table Higher in the stratigraphy, the clast composition changes 1. Two sandstone samples from the Snaunetten basin rapidly to become monomictic acid volcanic in composi- were chosen for analysis. Sample JL-04-30.1 was taken tion (Fig. 5e). In the southern part of the basin, the poly- from near the base of the basin succession in Haugset mict variety is missing. The conglomerate is mainly acid (inset B in Fig. 3). The host rock consists of a horizon- volcanic (Fig. 6a) becoming quartzite-dominated further tally laminated quartz-rich sandstone interbedded with up in the stratigraphy (Fig. 6b). Sedimentary structures poorly sorted, bouldery and polymictic conglomerates in the sandstones commonly include large-scale tabu- of acid volcanic, mafic volcanic and quartzitic composi- lar cross-beds, parallel lamination and some large-scale tion. Sample JL-04-75.2 was taken from near the top of trough cross-beds. The rock has a characteristic and del- the basin package in Førstøyl (inset A in Fig. 3), c.10 km icate pin-stripe lamination, defined by hematite grains. southwest from Haugset. It was collected from a massive There is a lack of well-defined channel structures. The silty sandstone which also contains quartzite conglomer- sedimentary facies of the conglomerates and sandstones ate clasts. 64 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY

Two samples were collected from the Lifjell Group and one sample from the Garvik quartzite. Sample JL-09- 14 from the Lifjell Group is from a thick sandstone bed between quartzite clastic conglomerates that occurs on the northwest side of Nordfjell. Under the microscope, the rock is seen to be an extremely deformed schistose quartz-muscovite rock, which was probably originally a quartz arenite. Almost all the framework minerals are recrystallised. Sample JL-09-13 was collected from the main Lifjell quartzite, just 10 metres above the previous sample. It was collected at the fault contact and is a highly sheared orthoquartzite. Sample JL-09-12 was collected in the southern part of the Lake Seljord area near Gar- vik and belongs to the Garvik quartzite. The rock rests- directly on top of the sheared Bø granite and is a sheared orthoquartzite, as the contact is tectonically altered by strong shear deformation.

U-Pb zircon method

Provenance of the sampled sediments is evaluated from detrital U-Pb zircon analyses and conglomerate clast lithology. Zircon grains were separated by standard­ methods including crushing, milling and heavy liquids­. U–Pb dating was performed using a Nu Plasma HR multi­collector ICPMS and a New Wave/Merchantek­ LUV-213 laser microprobe at the Department of Geosciences­, University of Oslo. Analytical methods are described briefly here. A full account is given in Røhr et al. (2008) and Rosa et al. (2009).

Masses 204, 206, 207 and 238 were measured and 235U was calculated from 238U using a natural 238U/235U=137.88. Mass number 204 was used as a moni- tor for common 204Pb. Raw data were reduced to U and 206Pb concentrations and U–Pb isotope ratios by a sample­ -standard bracketing routine similar to that of Jackson et al. (2004).

Figure 6. Conglomerates in the southern Snaunetten basin The U-Pb ages for samples JL-04-30.1 and JL-04-75.2 (Fig. 3a). Coordinates are in UTM/WGS84/zone 32V. (A) were calculated in 2005 using a single standard bracket­ Acid volcanic conglomerates dominate the lower part of the ing technique. This method gives good precision, but succession. This conglomerate is similar to the one pictured >1500 Ma old zircon tends to get inversely discordant. in Fig. 5e. (B) Conglomerate consisting almost entirely of An improved 2-3 standard method was developed later white quartzite clasts. Some acid volcanic clasts may be and the rest of the samples follow the new routine. The found as well. Note similar sedimentary facies association, zircon used for calibration included zircon standards typical for alluvial fans, in both photographs..

Table 1. Summary of samples analysed in this study. Sample Name* Unit Locality UTM coordinates Notes (WGS 84, zone 32V) JL-04-30.1 orthoquartzite Eidsborg Formation Haugset 460974 6610459 Gneissic recrystallized texture. JL-04-75.2 orthoquartzite Eidsborg Formation Førstøyl 455961 6600787 Gneissic recrystallized texture. JL-09-12 orthoquartzite Garvik quartzite Garvik 485822 6587558 Gneissic recrystallized texture. JL-09-13 orthoquartzite Lifjell Group/main quartzite Nordfjell 488482 6599947 Gneissic recrystallized texture. JL-09-14 muscovite schist Lifjell Group/Vallar Bru Fm. Nordfjell 488461 6600023 Gneissic recrystallized texture. NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 65

GJ-01 (609 ± 1 Ma; Jackson et al. 2004), 91500 (1065 ± 1 sample, but interpretations based on low grain counts Ma; Wiedenbeck et al. 1995), in-house Palaeoproterozoic should be applied with caution. Natural factors add standard A382 (1876 ± 2 Ma; Patchett & Kouvo 1986) another complexity. There is no way of knowing whether and an in-house standard Ceylon (553 ± 2 Ma; F. Corfu certain age-populations consisted of metamict grains pers. comm.). In our laboratory the GJ standard gave a that are now gone. The zircon fertility of rocks (felsic vs. concordia age of c.601 Ma and the 91500 gave a concor- mafic rocks) is important too (Moecher & Samson 2006), dia age of c.1059 Ma. These standards are known to be even some granites can be low in zircon. Although these slightly discordant, hence the discrepancy of concordia uncertainties are always present, other criteria, such as age from the upper intercept age. These values were used conglomeratic clast lithology and palaeocurrent mea- in calculations. IsoplotEx 3.0 (Ludwig 2003) was used to surements can be used to support zircon data. plot concordia and probability density diagrams. Zircon standard 91500 was also run as an unknown for check- The Snaunetten basin ing the accuracy of the method. Outlier standard analy- ses were rejected based on the outcome of the standard Two samples from the Snaunetten basin represent dif- run as unknown. This data can be found in Appendix 1. ferent sedimentary facies. Sample JL-04-30.1 from the Laser settings were: c.32 % power, 40 µm spotsize and 10 northern part is associated with polymictic alluvial fan Hz repetition rate. conglomerates. Detrital zircon shows pronounced peaks at 1123 Ma and 1482 Ma (Fig. 7). It is notable that the Palaeoproterozoic signal is very low, which is the oppo- Results site that is typically found in the older (Vindeggen Group) sediments from Telemark (Lamminen & Köykkä All the U-Pb results are listed in Appendix 2 and in Figs. 2010). Sample JL-04-75.2 from the southern part of the 7 and 8. In order to have statistical confidence, at least basin succession shows a distinctive 1518 Ma peak and 60 zircons (Dodson et al. 1988) should be analysed and minor peaks at c.1300 Ma, as well as a range of Palaeo- preferably 100 or more (Vermeesch 2004, 2005; Ander- and Archaean ages (Fig. 7). Although the sen 2005b). Analysing over 100 grains is unrealistic in amount of analysed grains in this sample is low, it can be most cases. It must be kept in mind that there is a slight stated confidently that the 1518 Ma is the dominant pop- probability that geologically significant small zircon pop- ulation. The 1123 Ma peak found in the north, was not ulations have gone undetected. However, major popula- detected, which could be a statistical issue. It also indi- tions show up early and c.30 grains should be enough to cates that the provenance in this part of the basin is dif- detect them. The relative heights of the peaks in diagrams ferent than in the north. reflect the relative abundance of an age population in the

Figure 7. Conventional con- cordia plots and probability density plots of the detrital zir- con samples from the Snaunet- ten basin. The 1480-1520 Ma peaks in both diagrams are most likely related to the Tud- dal Formation. In both samples the Palaeoproterozoic is rather minimal. For sample JL-04- 75.2, this could be due to the small number of grains studied. The young, 1123 Ma peak is missing in the lower probability density diagram. The so called “interorogenic” ages of 1300- 1200 Ma are present in these samples. 66 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY

Figure 8. Samples from the Lifjell Group and Garvik quartzite analysed in this study compared with those from the Vallar Bru Formation (Lifjell Group) analysed by de Haas et al. (1999). (A) The c.1155 Ma age of the Brunkeberg porphyry is absent from all samples. (B) The 1200-1300 Ma interval is common in young sediments from Telemark (see Fig. 7), but is missing here. (C) The c.1500 Ma is found in all except one sample. This is probably just due to low grain count. (D) The c.1730-1750 Ma interval is common for the Vindeggen Group (Lamminen & Köykkä 2010). This is found in all except one sample.

The Lifjell Group the new stratigraphic scheme, should underlie the main Probability density diagrams of samples from the Lifjell Lifjell quartzite (Fig. 10). This c.1760 Ma age is very Group are presented in Fig. 8. Sample JL-09-14 from a common in the Vindeggen Group and other quartzites in sandstone bed in a conglomeratic succession at Nordfjell Telemark, for example the Blefjell quartzite (Bingen et al. shows a distinctive c.1500 Ma peak. Some Palaeoprotero- 2001; Andersen et al. 2004a; Lamminen & Köykkä 2010) zoic ages are present and the youngest peak is 1387 Ma. (Fig. 9). Results from the main orthoquartzite of the Lifjell Group at Nordfjell (sample JL-09-13) are similar to the Upper The Garvik quartzite Brattefjell Member of the Brattefjell Formation (Fig. 9) (Lamminen & Köykkä 2010). The Palaeoproterozoic Sample JL-09-12 from the southern contact of the Tele- is most abundant in the age spectra and even Archaean mark Supracrustals at Garvik shows also a major c.1500 grains are relatively common. Major peaks can be found Ma mode (Fig. 8), and smaller but distinct Palaeopro- at 1760, 1884, 2700, 1626 and 1500 Ma. The 1500 Ma terozoic modes peaking at 1703 and 1837 Ma (Fig. 8). peak is much smaller than the 1760 Ma peak. When The youngest peak at 1320 Ma is defined by a single anal- the amount of analysed grains exceeds about 60, there ysis only. More grains were analysed from this sample is more confidence that the observed highest and low- than from sample JL-09-14, but these samples are virtu- est peaks are real. The 1760 Ma peak is important, since ally indistinguishable. It is likely that sample JL-09-12 is it is not present in sample JL-09-14 that, according to just a more deformed correlative to sample JL-09-14. NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 67

Figure 9. Probability density diagrams comparing the main quartzite of the Lifjell Group with the Vindeggen Group and the Blefjell quartzite. (A) The c.1550 Ma “Gothian gap” is characteristic for the Vindeggen Group (Lamminen & Köykkä 2010) and is also present in the Lifjell Group and Blefjell quartzite. (B) The c.1730-1750 Ma age is a major mode in all diagrams. The c.1500 Ma Tuddal signature is minor.

Figure 10. Schematic column across the conglomeratic lower part of the Lifjell Group (Vallar Bru Formation) in the Grunningsdalen-Slåkådalen fault system. Brecciated depositional surface is exposed at Heksfjellet. The detrital zircon age pattern obtained from the sandstone (JL-09-14) interbedded with conglomerates does not contain the same ca. 1760 Ma peak as in the sample from the Lifjell Group shallow marine sequence (JL-09-13) only 10 m above in the stratigraphy. Also the is missing in sample JL-09-14. Fieldmapping strongly suggests the presence of a fault between the sampling sites. Zircon evidence supports this. 68 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY

Provenance and correlation Group), mainly because of lithological similarity (Laajoki & Lamminen 2006). The polymictic conglomerate drap- The Snaunetten basin ing the basal contact in its northern part, in Haugset, is lithologically similar to the conglomerates of the Røyn- The Snaunetten basin succession in the north contains staul Formation around Lake Bandak (Fig. 1) and in a three different conglomerate types. The basal conglomer- number of other localities nearby (Laajoki & Lamminen ate is polymictic in the northernmost tip of the basin (Figs. 2006). New detrital zircon data place new constraints 3, 5b and c). The sandstone sample (JL-04-30.1) analysed on the stratigraphic position of the Snaunetten succes- from a bed in the conglomeratic deposit has distinctive sion. Field data show that the thickness of sediments in age modes at 1123 Ma and 1480 Ma. Palaeoproterozoic the Snaunetten basin is more than 1 km and that there zircons are rare. The facies is a parallel-laminated sheet- are no interlayers of volcanic rocks. Detrital zircons from flood sandstone, interpreted to commonly accompany the sample close to the bottom of the Snaunetten suc- mass-flow conglomerates in alluvial fan settings (e.g. Blair cession constrain deposition to be younger than 1123 & McPherson 1994). Since Palaeoproterozoic are typically Ma. The Eidsborg Formation is the only regional unit abundant in the Gausta quartzites (Lamminen & Köykkä which shares these characteristics. The maximum sedi- 2010), this suggests that the nearby Gausta quartzites were mentation age for the Snaunetten basin is equivalent to not sourced extensively, but that the material came mainly the 1118 ± 38 Ma youngest detrital zircon age from the from an area lying to the present northwest. The presence Eidsborg Formation in the small dataset of de Haas et al. of quartzite clasts similar to the Gausta Formation of the (1999). The type locality of the Eidsborg Formation is sit- Vindeggen Group in the conglomerates indicates some uated some 5 km southeast from the Snaunetten basin sourcing from the east, too. Further up in the stratigraphy, at Lake Bandak (Fig. 1); the Snaunetten basin thus rep- the composition of the conglomerate changes rapidly to resents an outlier of the Eidsborg Formation preserved contain only acid volcanic clasts, which is the most abun- from erosion in a down-faulted crustal block. An uncon- dant clast type in the entire basin. This means that the formity below the Eidsborg Formation was predicted fault bounding the basin to the west became more active by Laajoki et al. (2002), but not supported by data. The than the one in the east. Alluvial fans are typical in fault present study shows for the first time that the Eidsborg bordered basins and their evolution is commonly directly Formation overlies both the Vemork and the Tuddal for- related to the activity of the fault. mations, and also the Oftefjell Group. At Lake Bandak it overlies the Høydalsmo Group. A schematic model of the Detrital zircon from the southern part of the basin (sam- Snaunetten basin is shown in Fig. 11. ple JL-04-75.2) shows a major 1520 Ma peak, and the rest of the peaks are more or less equally abundant. The The Lifjell Group and the Garvik quartzite complete absence of a 1123 Ma peak is a notable differ- ence from the north. Also the 1520 Ma peak is older than Sample JL-09-14 from the Vallar Bru Formation at Nor- the 1480 Ma found in the north, which may be related dfjell has a major peak at c.1500 Ma (Fig. 8). The strong to local differences in the age of the Tuddal Formation. 1500 Ma peak indicates Tuddal Formation as the prin- The Tuddal Formation is large and its age-structure is cipal source. This is supported by the presence of felsic unknown. clasts in the conglomerate in the lower part of the succes- sion (Heksfjellet conglomerate, Laajoki et al. 2002). Laa- The c.1500 Ma ages are probably related to the Tud- joki et al. (2002) dated one clast from the nearby Heks- dal volcanism and the younger c.1123 Ma age is early fjellet and also obtained a c.1500 Ma age indicating der- Sveconorwegian magmatism. The northern part of the ivation from the Tuddal Formation. The Palaeoprotero- Tuddal Formation has some igneous intrusives (The zoic signature in sample JL-09-14 is most likely recycled Uvdal plutonic belt), from which the granite has from the Vindeggen Group quartzites. been dated at 1476 ± 13 Ma (Andersen et al. 2002). No age determinations have been made from the southern Sample JL-09-13 from the main Lifjell Group quartzite part of the Tuddal Formation. The youngest dated por- at Nordfjell contains a significant amount of Palaeopro- phyry in Telemark is the Skogsåa porphyry at 1145 ± 4 terozoic and older grains. The c.1500 Ma peak is minor. Ma (Laajoki et al. 2002), which is somewhat older than The sample itself was sampled close to the sampling site the youngest age peak found in the Snaunetten basin. of JL-09-14, on the eastern side of an apparent fault con- The youngest volcanic rocks in Telemark, sources of the tact. The provenance signature is drastically different and 1123 Ma peak, may have been eroded away. An enigmatic such a rapid change is not likely to be sedimentary. feature of the Mesoproterozoic sediments in South Nor- way is the presence of Archaean zircon. No un­ambiguous Lamminen & Köykkä (2010) found a trend in the detri- solution to this problem exists, but the Lewisian of Scot- tal zircon population in the Vindeggen Group where land or origins are most likely. the uppermost parts contained the largest amount of Palaeoproterozoic and older zircon, while the lower- The Snaunetten basin has recently been included in most parts were dominated by c.1500 Ma zircon directly the 1155-1150 Ma Røynstaul Formation (Høydalsmo related to the Tuddal magmatism. Due to the covering NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 69

Figure 11. Basin model for the Snaunetten basin. The Raudsinutan fault is a major boundary between two contrasting lithologies: Rjukan Group volcanics and Vindeggen Group quartzites. The basin history is characterised by episodic activation and de-activation of the boundary faults, reflected in variable conglomerate compositions in the basin.

of local rocks by shallow shelf sediments, the local been detected from the Sørkjevatn porphyry, so a sub- (c.1500 Ma) signal becomes strongly reduced. If the volcanic origin for the rock is not excluded (Bingen et al. Lifjell Group is correlated with the Vindeggen Group, 2003; Andersen et al. 2004a). In Fig. 9 the detrital zircon then the Lifjell Group would fit in this trend and even age pattern from the Blefjell quartzite shows a striking contain a significant Archaean population to signify similarity with the Lifjell Group. distant sources. Based on this and on sedimentological similarity, the part of the Lifjell Group analysed in the The Vallar Bru Formation and associated deposits have present study seems to correlate with the Upper Bratte- probably survived from later erosion in a fault zone. It fjell Member (Lamminen & Köykkä 2010) of the Bratte­ is possible that the Slåkådalen-Grunningsdalen fault is fjell Formation. In the study area, the Upper Bratte­ an early sign of Sveconorwegian activity in the bedrock, fjell Member is located on the NW side of Nordfjell, on before the more dynamic period began. Deep fault sys- the other side of the Slåkådalen-Grunningsdalen fault tems are ideal for preservation of rocks from erosion, system­ (Fig. 2). which is probably the reason why today we find these conglomerates only within the fault zone. Although pre- Many isolated orthoquartzite units occur in the Precam- vious field evidence has suggested that the Lifjell Group brian bedrock of South Norway (Bingen et al. 2001). overlies the Brunkeberg porphyry, critical examination Among them the Blefjell quartzite (Andersen et al. of the field descriptions (Laajoki 2002a; Laajoki 2006b) 2004a) is a strongly deformed mature sandstone unit in and the author’s own field studies reveal that many of the eastern Telemark close to the Heddal Group. This unit contacts are in fact not exposed, are strongly sheared, or poses a similar problem as the Lifjell Group. Field studies their syndepositional status is otherwise unclear. As the have suggested that it either underlies a porphyry dated Vallar Bru and correlative conglomerates bordering the at 1159 ± 8 Ma (Sørkjevatn Formation, Bingen et al. Lifjell Group are intensively sheared and stretched, the 2003), or overlies it (Andersen et al. 2004a), but no detri- younging direction for the beds is impossible to deter- tal zircon younger than 1404 ± 11 Ma has been found mine. The entire southern part of the Telemark Supra- from the sandstone (Andersen et al. 2004a). The contact crustals appears to be cut into numerous thrust sheets, between the Blefjell quartzite and the Sørkjevatn Forma- which is also evident from the terraced landscape around tion is also similar to that of the Lifjell Group and its sup- the Seljord. Two important questions arise. (1) Are the posed basal contact with the Brunkeberg Formation por- Vallar Bru and correlative conglomerates overturned and phyry. Also here one can find a quartzite conglomeratic in fact underlying the Brunkeberg porphyry? (2) Is the unit (Surtetjørn Formation; Andersen et al. 2004a) and Lifjell Group completely allochthonous and its appar- several amphibolites. Thus the setting is analogous to ent position above the conglomerates due to tectonism the southern contact of the Telemark Supracrustals; see rather than sedimentation? Andersen et al. (2004a) for detailed descriptions of this area. No distinctive evidence for a volcanic origin has 70 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY

Diabase dykes in Telemark the interpretation of Laajoki et al. (2002): 1) Deposition The Telemark Supracrustals contain several diabase (dol- of the mineralogically mature sandstones of the Lifjell erite) dykes at almost all stratigraphic levels. They are Group are governed by marine processes, while all the especially abundant in the Vindeggen Group where two other known sediments of the Sveconorwegian succes- have been dated. Near the town of Rjukan, the Hesjåb- sion are continental and alluvial 2) The Lifjell Group is utind gabbro was dated at 1145 +3/-2 Ma by (Dahlgren thick, while individual formations in the Sveconorwegian et al. 1990b) and near the town of Høydalsmo, the Sand- succession are relatively thin; 3) The Lifjell Group does vik diabase was dated at 1347 ± 4 Ma by Corfu & Laa- not contain any detrital zircons around 1155 Ma, in spite joki (2008). Both basaltic volcanism and the appearance of the fact that the Brunkeberg porphyry is interpreted of a dyke swarm in a region indicate crustal extension. to underlie the Lifjell Group via a weathering crust. The The dykes are commonly oriented parallel to the origi- weathering crust itself argues for prolonged subaerial nal bedding, resembling sills, or parallel to the regional exposure and recycling of zircon in the overlying sedi- structural grain. It is not known how many generations ment; 4) Several zircon age modes at around 1250 Ma are of dykes exist in Telemark. However, diabase dykes are widely abundant in the Sveconorwegian succession (Bin- very rare in the Bandak basin. As diabase dykes usually gen et al. 2003; Lamminen et al. 2009; this study), but are denote a distinct event in geological history, they could completely lacking in the Lifjell Group. be used to correlate problematic rock units in southwest Norway. For example the Lifjell Group and the Vallar Bru If the Lifjell Group was indeed deposited at the same time conglomerates are heavily penetrated by dykes, which is as the continental Sveconorwegian succession, it should also true for the Blefjell quartzite further in the east. This have been deposited on a shallow shelf or/and in a tidal reasoning would make the Vallar Bru conglomerates and flat environment. This kind of environment gets its detri- the Lifjell Group older than most of the Bandak Group. tus from continents by rivers, which according to such a timing would have been a Sveconorwegian mountain range at that time. Thus, it would be logical to think that Discussion those rivers were eventually discharged into the sea carry- ing some < 1350 Ma zircons that would have ended up in If heavy minerals are going to be used for correlation the shallow shelf where the Lifjell Group should have been purposes, the sedimentary environment needs to be well deposited. The abundance of diabase dykes in the Lifjell known. A multi-mineral approach including garnet, zir- Group supports the detrital zircon findings that it must con and rutile has been used successfully in the correla- correlate with the Vindeggen Group, considered here to tion of Palaeozoic sediments of the North Sea (e.g. Mor- have been deposited between 1500 and 1350 Ma. Dating ton 2009). Ideally the sampled sediments are from a one of these dykes would solve this problem conclusively. facies that represents a sedimentary environment where the sediment has beenwell mixed and homogenised. Lat- The variety of early Sveconorwegian conglomerate depo- eral variability in the provenance could lead to erroneous sits in Telemark correlations. The present study illustrates this phenome- non. In a shallow marine shelf sedimentary environment, The Sveconorwegian succession in Telemark is known homogenisation is very likely due to continuous wave for its lithological variability. It is almost completely con- and tidal action and presence of alongshore currents. tinental and includes diverse conglomerates that change Conversely, in alluvial environments, rivers have tribu- even within the same formation. Most conglomerates are taries that may have different provenances. Also mixing mass flow type deposits that were laid down in alluvial in a fluvial environment is not necessarily efficient. Sta- fans, some are interpreted as gravelly braided streams tistical representativity of the samples and random phe- (Köykkä & Laajoki 2009; Köykkä 2011). A gallery of dif- nomena itself add another complication. The detrital zir- ferent conglomerates is shown in Fig. 12. It shows that con method gives fundamentally different information the oldest known Sveconorwegian conglomerate, the than field mapping, but has a clear advantage in being Svinsaga conglomerate, consists only of quartzite clasts an objective method. In a complexly deformed area like (Fig. 12a-b). Most of the clasts are red and can be read- Telemark, field relationships are difficult to establish ily traced to the Brattefjell Formation of the Vindeggen and key lithological contacts are almost always deeply Group. The upper member of the Brattefjell Formation covered by vegetation or are strongly sheared, thus it is is an unusually bright red quartzite unlike any other in possible to misinterpret tectonically formed contacts Telemark. The Vallar Bru conglomerate is dominated by between adjacent different lithologies to be primary dep- white quartzite clasts, but include some felsic clasts too ositional contacts, and vice versa. (Fig. 12c). Younger conglomerates include acid volcanic clasts and basalt clasts. The Langelinutane Member of The Lifjell Group was elevated to group status by Laajoki the Ofte Formation (Oftefjell Group) has typically only et al. (2002), after U-Pb dating of the Brunkeberg por- porphyry clasts (Laajoki 2006a) (Fig. 12d). The Røyn- phyry to 1155 ±2 Ma. This placed paramount importance staul and Eidsborg conglomerates are polymictic con- on the nature of the porphyry and especially its field rela- taining various porphyry types, epidotised basalt clasts tionships. Several observations nevertheless question and white quartzites (Laajoki & Lamminen 2006) (Fig. NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 71

Figure 12. A gallery illustrating conglomerate clast variability from the Sveconorwegian succession in Telemark. The photographs have been slightly color-enhanced to bring out detail better. (A-B) Conglomerates of the Svinsaga Formation are only made of quartzites, mostly the red quartzite which is characteristic for the Upper Brattefjell Member of the Brattefjell Formation (Photos by J. Köykkä). The stick is c.1 m long. (C) The Vallar Bru Formation is mainly made of white quartzite clasts, but includes some reddish porphyry clasts as well. (D) The Langelinutane Member of the Ofte Formation is almost solely made of various porphyry clasts. (E) The Eidsborg Formation is characteristically polymictic in the basal part including quartzite, porphyries, basalt and schist clasts. (F) A conglomeratic unit called the Kultankriklan conglomerate, can be found as an outlier deposited on top of tilted Vindeggen Group. This unit was originally correlated with the Røynstaul Formation by Laajoki & Lamminen (2006). It can also be correlative with the Eidsborg Formation. Size of nameplate is c.15 cm long. (G) The Eidsborg Formation contains white quartzite and grey granite clasts in its uppermost part.

12e-g). The Eidsborg Formation is especially varied and hinterland, exposing different rocks for erosion. In pull- its clast composition varies over short distances. The apart basins, large lateral movements may move the uppermost conglomerates of the Eidsborg Formation basin from one source area to another. The same fault include abundant granite clasts, which could reflect base- activity also changes the sediment dispersal pattern. For ment exposure. the majority of the conglomerates in Fig. 12, the clasts are either quartzites or acid volcanics, but polymictic The change of conglomerate clast composition within varieties with basic volcanite clasts are present too. Gran- a short distance is an indication of a dynamic sedimen- ite clasts are extremely rare in most of the conglomerates, tary environment, probably a pull-apart basin regime which suggests that the crystalline basement was not well with drainage areas of restricted extent, reflecting local exposed. Most of the quartzites are probably recycled bedrock source rocks. Fault-block tilting and the acti- from the Vindeggen Group and the porphyries are either vation and deactivation of faults lead to changes in the from the Tuddal volcanics or younger. Pull-apart basins 72 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY are usually short-lived and rapidly subsiding basins. sedimentary cover. At the end of the post rift develop- They occur in many tectonic settings. A Basin and Range ment in the Rjukan rift basin, South Norway was covered analogy has been suggested for the Telemark area (Dahl- by a shallow sea that left thick quartzitic deposits. These gren et al. 1990a; Bingen et al. 2003). The geochemistry are now found in Telemark (upper part of the Vindeg- of the bimodal magmatic rocks supports this analogy gen Group), Hardangervidda (Hettefjorden and Festning- (see discussion in Bingen et al. 2003). snutan groups) and possibly in Bamble and Kongsberg (Kragerø and Modum complexes). A detailed account of the Rjukan rift basin is given in Lamminen & Köykkä Early Sveconorwegian basin (2010). development ­in Telemark If we consider the Lifjell Group as being part of the Vin- deggen Group, then the early Sveconorwegian starts with A model for the development of the Telemark Supra- the deposition of the Vallar Bru Formation. The quartz- crustals is presented in Fig. 13. The Mesoproterozoic his- itic cover, left from a long tectonically quiet period, tory of the Telemark Supracrustals starts with the Rju- was dissected by faults, and small basins were formed kan rift basin, which contains a volcanic core and a thick where alluvial fans sourced almost exclusively the old

Figure 13. Schematic model for the evolution of the Telemark Supracrustals. (A) Extensional period. The start of the Rjukan Rift Basin involved an enormous amount of bimodal volcanism. It was followed by a long period of sedimentation without volcanism. (B) It is likely that the whole of S Norway was covered by shallow marine sediments and the Rjukan Rift Basin was buried under these. (C) The Vindeggen Group sedimentation was terminated at c.1350 Ma, which is constrained by a diabase sill. A deep regolith was developed on the Vindeggen Group. (D) The thick cratonic cover started to rift apart giving rise to the Svinsaga Formation, and probably the Vallar Bru Formation (V) was deposited first during this period. The first Sveconorwegian volcanic rock overlies the Svinsaga Formation. (E) Extension was concentrated at the southern part of Telemark, where the Bandak basin was formed. It was rapidly filled with bimodal volcanics and coarse sediments. The Oftefjell and Høydalsmo groups were deposited at this time. Occasional periods of rift inversions might have taken place. (F) The extensional period changed into compressional regime and new pull-apart basins were formed. The Snaunetten basin (S) was initiated. NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 73

Vindeggen quartzites. The Tuddal Formation was locally deformed and probably dislocated part of the Vindeggen exposed and subjected to erosion. Probably simultane- Group whereas the conglomeratic basal part, the Vallar ously, the Bandak rift basin started to form in the south, Bru conglomerate, is probably much younger, correlative creating accommodation space for the sediments of the to the Sveconorwegian succession. The Garvik quartzite Svinsaga Formation. The conglomerates of the Svinsaga at the southern border of the Telemark Supracrustals is Formation contain solely quartzites and lack porphyries. also probably correlative to the Vallar Bru conglomerate and coeval units. The Lifjell Group does not contain any The tectonic activity increased and was concentrated zircon from the c.1155 Ma Brunkeberg Porphyry that has in the Bandak rift basin and further to the northeast been mapped to underlie the conglomeratic basal part, in the Heddal basin. The basin widened and was sub- or from any other volcanic rock of early Sveconorwe- ject to bimodal magmatic episodes and possibly basin gian time. It is possible that the Brunkeberg porphyry is inversion, creating angular unconformities and erosion a subvolcanic dyke, or that the Vallar Bru conglomerate of previous deposits. The numerous diabase dykes in was deposited earlier than the porphyry was emplaced. the Vindeggen Group could have been feeder dykes for It is suggested that the Lifjell Group is abandoned as a the Sveconorwegian magmatism, as suggested by Dons lithostratigraphic unit. (1962). Basin inversions led to the more polymictic char- acter of the conglomerates. Gradual crustal thicken- ing did not allow the fractures to penetrate to the man- Acknowledgements – Emeritus professor Kauko Laajoki is thanked for tle anymore. The evolution changed from “thin-skinned” introducing the author to the Telemark area. Professors Johan Petter Nystuen and Tom Andersen are thanked for discussions. Siri Simonsen to “thick skinned” tectonism (sensu Allen & Allen 2005). is thanked for help with the mass spectrometer. Juha Köykkä is thanked The polymictic Eidsborg conglomerates and sandstones for some photographs. Bernard Bingen and an anonymous reviewer were deposited all over Telemark. are thanked for comments that improved the manuscript. Adrian Read is thanked for comments and correcting the language. This is part of This study shows indirectly that the Raudsinutan fault the author’s PhD thesis on Proterozoic basins in South Norway. This is Contribution No. 18 from the Isotope Geology Laboratory at the bordering the Snaunetten basin succession and the Department of Geosciences, University of Oslo. Slåkådalen-Grunningsdalen fault zone bordering the Lifjell Group, were likely synsedimentary and already active in early Sveconorwegian times and have been pre- References served until today. The Lifjell Group and the Slåkådalen- Grunningsdalen fault zone are overlain by the 1145 ± 4 Åhäll, K.-I. & Connelly, J.N. 2008: Long-term convergence along SW : 330 m.y. of Proterozoic crustal growth. Precambrian Ma Skogsåa porphyry (Laajoki et al. 2002; Laajoki 2002b) Research 161, 452-472. at the base of the Heddal Group (Fig. 2). This places time Allen, P.A. & Allen, J.R. 2005: Basin Analysis: Principles and Applica- constraints on the faulting event in the Slåkådalen-Grun- tions. Second Edition. 2005. Blackwell Publishing. 549 pp. ningsdalen fault zone and supports the model where the Andersen, T. 2005a: analysis, regional nomenclature and crus- Vallar Bru Formation is the oldest unit in the Sveconor- tal evolution in southwestern Fennoscandia. GFF 127, 157-166. wegian succession. Andersen, T. 2005b: Detrital zircons as tracers of sedimentary prove- nance: limiting conditions from statistics and numerical simula- tion. Chemical Geology 216, 249-270. Andersen, T., Griffin, W.L. & Sylvester, A.G. 2007: Sveconorwegian Conclusions crustal underplating in southwestern Fennoscandia: LAM-ICPMS U–Pb and Lu–Hf isotope evidence from granites and gneisses in U-Pb zircon from a sandstone-conglomerate unit, the Telemark, southern Norway. Lithos 93, 273-287. Snaunetten basin, in central Telemark, shows abundant Andersen, T., Laajoki, K. & Saeed, A. 2004a: Age, provenance and zircon with ages: c.1120, 1300 and 1480-1510 Ma and tectono­stratigraphic status of the Mesoproterozoic Blefjell quart- some Palaeoproterozoic and Archaean ages. This rock zite, Telemark sector, southern Norway. Precambrian Research 135, 217-244. unit unconformably overlies the Rjukan Group and is Andersen, T., Sylvester, A.G. & Andresen, A. 2002: Age and petro­ correlative to the youngest stratigraphic units of the Tele- genesis of the Tinn granite, Telemark, South Norway, and its geo- mark Supracrustals, which are the Kalhovd and Eids- chemical relationship to metarhyolite of the Rjukan Group. NGU borg formations. The c.1500 Ma aged zircon comes from Bulletin 440, 19-26. the Tuddal volcanics or associated plutonic rocks in the Andersen, T., Griffin, W.L., Jackson, S.E., Knudsen, T.L. & Pearson, north, and the younger grains can be matched with rocks N.J. 2004b: Mid-Proterozoic magmatic arc evolution at the south- in south and southwest Telemark. The Snaunetten basin west margin of the Baltic shield. Lithos 73, 289-318. Atkin, B.P. & Brewer, T.S. 1990: The tectonic setting of basaltic mag- shows a rapid switching of provenance which indicates a matism in the Kongsberg, Bamble and Telemark sectors, Southern dynamic tectonic environment. Norway. In: Gower, C.F., Rivers, T. & Ryan, B. (eds.): Mid-Protero- zoic -. Geological Association of Canada Special The Lifjell Group and its basal conglomerates show no paper 38, 471-483. evidence of detrital zircon younger than c.1350 Ma. Bingen, B., Nordgulen, Ø. & Viola, G. 2008: A four-phase model for Based on detrital zircon U-Pb ages, sedimentologi- the Sveconorwegian orogeny, SW Scandinavia. Norwegian Journal cal similarity, and the abundance of diabase dykes, it of Geology 88, 43-72. Bingen, B., Birkeland, A., Nordgulen, Ø. & Sigmond, E.M.O. 2001: is concluded that the Lifjell Group represents a highly Correlation of supracrustal sequences and origin of terranes in the 74 J. Lamminen NORWEGIAN JOURNAL OF GEOLOGY

Sveconorwegian orogen of SW Scandinavia: SIMS data on zircon Dons, J.A. 1972: The Telemark Area, a brief presentation. Sciences de la in clastic metasediments. Precambrian Research 108, 293-318. Terre 17, 25-29. Bingen, B., Mansfeld, J., Sigmond, E.M.O. & Stein, H. 2002: Baltica- Dons, J.A. 2004: Berggrunnskart ÅMOTSDAL 1514 II - M 1:50 000. Laurentia link during the Mesoproterozoic: 1.27 Ga development Norges geologiske undersøkelse. of continental basins in the Sveconorwegian Orogen, southern Fryberger, S.G. & Schenk, C.J. 1988: Pin stripe lamination: a distinct­ Norway. Canadian Journal of Earth Sciences 39, 1425-1440. ive feature of modern and ancient eolian sediments. Sedimentary Bingen, B., Nordgulen, Ø., Sigmond, E.M.O., Tucker, R., Mansfeld, J. Geology 55, 1-15. & Högdahl, K. 2003: Relations between 1.19-1.13 Ga continental Gaál, G. & Gorbatschev, R. 1987: An outline of the Precambrian evolu- magmatism, sedimentation and metamorphism, Sveconorwegian tion of the Baltic Shield. Precambrian Research 35, 15-52. province, S Norway. Precambrian Research 124, 215-241. Gorbatschev, R. & Bogdanova, S. 1993: Frontiers in the Baltic Shield. Bingen, B., Øyvind, S., Marker, M., Sigmond, E.M.O., Nordgulen, Ø., Precambrian Research 64, 3-21. Ragnhildstveit, J., Mansfeld, J., Tucker, R.D. & Liégeois, J-P. 2005: Högdahl, K., Andersson, U.B. & Eklund, O. (eds.) 2004: The Trans- Timing of continental building in the Sveconorwegian orogen, SW scandinavian Igneous Belt (TIB) in Sweden: a review of its charac- Scandinavia. Norwegian Journal of Geology 85, 87-116. ter and evolution. Geological Survey of Finland Special Paper 37. Blair, T.C. & McPherson, J.G. 1994: Alluvial fans and their natu- 125 pp. ral distinction­ from rivers based on morphology, hydraulic Jackson, S.E., Pearson, N.J., Griffin, W.L. & Belousova, E.A. 2004: The processes­, sedimentary processes, and facies assemblages. Journal application of laser ablation-inductively coupled plasma-mass of Sediment­ary Research 64A, 450-489. spectrometry to in situ U–Pb zircon geochronology. Chemical Geo- Brewer, T.S. & Atkin, B.P. 1987: Geochemical and tectonic evolution logy 211, 47-69. of the Proterozoic Telemark supracrustals, southern Norway. In: Johansson, L., Möller, C. & Söderlund, U. 2001: Geochronology of Pharaoh­, T.C., Beckinsale, R.D. & Rickard D.T. (eds.): Geochemi­ eclogite facies metamorphism in the Sveconorwegian Province of stry and mineralization of Proterozoic volcanic suites. Geological SW Sweden. Precambrian Research 106, 261-275. Society Special Publication 33, 471-487. Knudsen, T.-L., Andersen, T., Whitehouse, M.J. & Vestin, J. 1997: Brewer, T.S. & Menuge, J.F. 1998: Metamorphic overprinting of Sm-Nd Detrital zircon ages from southern Norway – implications for the isotopic systems in volcanic rocks: the Telemark Supergroup, Proterozoic evolution of the southwestern Baltic Shield. Contri­ southern Norway. Chemical Geology 145, 1-16. butions to Mineralogy and Petrology 130, 47-58. Bogdanova, S.V., Bingen, B., Gorbatschev, R., Kheraskova, T.N., Koistinen, T., Stephens, M.B., Bogatchev, V., Nordgulen, Ø., Wenner­ Kozlov­, V.I., Puchkov, V.N. & Volozh, Yu.A. 2008: The East Euro- ström, M. & Korhonen, J. (compilers) 2001: Geological map of pean Craton (Baltica) before and during the assembly of . the Fennoscandian Shield, scale 1:2 000 000. Geological Surveys Precambrian Research 160, 23-45. of Finland­, Norway and Sweden and the Northwest Department of Bugge, C. 1931: Geologiske undersøkelse i Telemark. Norsk Geologisk Natural Resources of Russia. Tidsskrift 12, 149-170. Köykkä, J. 2010: Lithostratigraphy of the Mesoproterozoic Telemark Corfu, F. & Laajoki, K. 2008: An uncommon episode of mafic magma­ supracrustal rocks, South Norway: revision of the sub-Hedders­ tism at 1347 Ma in the Mesoproterozoic Telemark supracrustals,­ vatnet unconformity and geochemistry of basalts in the Hedders- Sveconorwegian orogen—Implications for stratigraphy and vatnet Formation. Norwegian Journal of Geology 90, 49-64. tectonic­ evolution. Precambrian Research 160, 299-307. Köykkä, J. 2011: The sedimentation and paleohydrology of the Meso- Dahlgren, S. & Heaman, L. 1991: U–Pb constraints for the timing of proterozoic stream deposits in a strike–slip basin (Svinsaga Forma- middle Proterozoic magmatism in the Telemark region, Southern tion), Telemark, southern Norway. Sedimentary Geology 236, 239- Norway. Geological Association of Canada Annual Meeting, 255. Program­ and Abstracts 16, A28. Köykkä, J. & Laajoki, K. 2009: Mesoproterozoic frost action at the Dahlgren, S., Heaman, L. & Krogh, T., 1990a: Geological evolution base of the Svinsaga Formation, central Telemark, South Norway. and U-Pb geochronology of the Proterozoic Central Telemark area, Norwegian­ Journal of Geology 89, 291-303. Southern Norway. Geonytt 17, 38-39 (abstract). Laajoki, K. 1998: Stratigraphic and tectonic significance of the Vallar Dahlgren, S.H., Heaman, L. & Krogh, T.E. 1990b: Precise U–Pb zircon Bru and Eidet conglomerates of the middle Proterozoic Seljord and baddeleyite age of the Hesjåbutind gabbro, Central Telemark group, southern Telemark, Norway. 23. Nordiske Geologiske Vinter- area, southern Norway. Geonytt 17, p. 38 (abstract). möde, Århus, 13-16 January, 1998, p. 167. de Haas, G.J.L.M., Andersen, T. & Vestin, J., 1999: Detrital zircon Laajoki, K. 2000: Primary and tectonic relationships between the geochronology: new evidence for an old model for of the Middle Proterozoic Svinsaga formation (Bandak group) and the SW Baltic Shield. Journal of Geology 107, 569-586. Seljord group, southern Telemark, Norway. Geonytt 1, p. 114. Dodson, M.H., Compston, W., Williams, I.S. & Wilson, J.F. 1988: A Laajoki, K. 2002a: Lithostratigraphy of the lower part of the Lifjell search for ancient detrital zircons in Zimbabwean sediments. Jour- group, Telemark, Norway. Res Terrae A23. Publications of the nal of the Geological Society 145, 977-983. Department of Geosciences, University of Oulu. 47 pp. Dons, J.A. 1959: Fossils (?) of Precambrian age from Telemark, Laajoki, K. 2002b: The Mesoproterozoic sub-Heddal unconformity, southern Norway. Norsk Geologisk Tidsskrift 39, 249-262. Sauland, Telemark, south Norway. Norsk Geologisk Tidsskrift 82, Dons, J.A. 1960a: Telemark supracrustals and associated rocks. In: 139-152. Holtedahl, O. (ed.): . Norges geologiske under- Laajoki, K. 2003: Basal parts of the middle Proterozoic Svinsaga for- søkelse 208, 49-58. mation on the Svafjell, Meien and Sjånuten mountains, Telemark, Dons, J.A. 1960b: The stratigraphy of supracrustal rocks, granitization South Norway. NGF Abstracts and Proceedings 1, p. 51. and tectonics in the Precambrian Telemark area, Southern Norway. Laajoki, K. 2005: The Mesoproterozoic sub-Heddersvatnet Norges geologiske undersøkelse 212h, 1-30. un­conform­ity, Telemark, South Norway. Bulletin of the Geological Dons, J.A. 1962: The Precambrian Telemark area in South Central Society of Finland 77, 49-63. Norway. Geologische Rundschau 52, 261-268. Laajoki, K. 2006a: Lithostratigraphy of the Mesoproterozoic Oftefjell Dons, J.A. 1963: De prekambriske bergarter i Telemark; I, Gruber og group, central Telemark, Norway. Res Terrae A24. Publications of skjerp innen gradteigkart E36V, Kviteseid; The Precambrian rocks the Department of Geosciences, University of Oulu. 36 pp. of the Telemark area in south central Norway; I, mines and claims Laajoki, K. 2006b: The Mesoproterozoic sub-Lifjell unconformity, within the quadrangle map E36W, Kviteseid. Norges geologiske central­ Telemark, Norway. Bulletin of the Geological Society of undersøkelse 216. Finland ­ 78, 41-70. NORWEGIAN JOURNAL OF GEOLOGY Provenance and correlation of sediments in Telemark, South Norway 75

Laajoki, K. 2009: The Mesoproterozoic sub-Svinsaga unconformity, Starmer, I.C. 1993: The Sveconorwegian Orogeny in Southern Norway, central Telemark, Norway. Res Terrae A26. Publications of the relative to deep crustal structures and events in the North Atlantic Department of Geosciences, University of Oulu. 34 pp. Proterozoic . Norsk Geologisk Tidsskrift 73, 109-132. Laajoki, K. & Corfu, F. 2007: Lithostratigraphy of the Mesoproterozoic­ Starmer, I.C. 1996: Accretion, rifting, rotation and collision in the Vemork formation, central Telemark, Norway. Bulletin of the North Atlantic supercontinent, 1700-950 Ma. In: Brewer, T.S. (ed.): Geological ­Society of Finland 79, 41-67. Precambrian Crustal Evolution in the North Atlantic Region. Vol Laajoki, K. & Corfu, F., 2008. An uncommon episode of mafic magma­ 112. Geological Society of London Special Publication 112, 219-248. tism at 1347 Ma in the Mesoproterozoic Telemark supracrustals, Stephens, M.B., Wahlgren, C.H., Weijermars, R. & Cruden, A.R. 1996: Sveconorwegian orogen—Implications for stratigraphy and tecto- Left lateral transpressive deformation and its tectonic implications, nic evolution. Precambrian Research 160, 299-307. Sveconorwegian Orogen, Baltic Shield, Southwestern Sweden. Pre- Laajoki, K. & Lamminen, J. 2004: Role of the Mesoproterozoic Research 79, 261-279. Telemark­ supracrustals in the assembly of Rodinia. 32nd IGC Flo- Torske, T. 1985: Terrane displacement and Sveconorvegian rotation rence 2004 – Scientific Sessions: abstracts (part 2), p. 872. of the Baltic Shield: a working hypothesis. In: Tobi, A.C. & Tou- Laajoki, K. & Lamminen, J. 2006: The Mesoproterozoic sub-Røynstaul ret, J.L.R. (eds.): The Deep Proterozoic Crust in the North Atlantic unconformity, central Telemark, Norway. Norwegian Journal of Provinces. NATO Advanced Study Institute Series, Series C 158, 333- Geology 86, 29-40. 343. Laajoki, K., Corfu, F. & Andersen, T. 2002: Lithostratigraphy and U-Pb Törnebohm, A.E. 1889: Några notiser från en geologisk resa i geochronology of the Telemark supracrustals in the Bandak-Sau- Telemarken­. Geologiska Förenings i Stockholm Förhandlingar 11, land area, Telemark, South Norway. Norwegian Journal of Geology 46-62. 82, 119-138. Vermeesch, P. 2004: How many grains are needed for a provenance Lamminen, J. & Köykkä, J. 2010: The provenance and evolution of the study? Earth and Planetary Science Letters 224, 441-451. Rjukan Rift Basin, Telemark, south Norway: the shift from a rift Vermeesch, P. 2005: Statistical uncertainty associated with histograms basin to an epicontinental sea along a Mesoproterozoic superconti- in the Earth sciences. Journal of Geophysical Research 110, B02211, nent. Precambrian Research 181, 129-149. 15 pp. Lamminen, J., Köykkä, J., Andersen, T. & Nystuen, J.P. 2009: From Viola, G. & Henderson, I.H.C. 2010: Inclined transpression at the toe Extension to Transtension: the Telemark Supracrustals, ca. 400 Ma of an arcuate thrust: an example from the Precambrian ’Mylonite Sedimentary Record of Variable Tectonics Before and During the Zone’ of the Sveconorwegian orogen, In: Law, R., Butler, R., Holds- Sveconorwegian (Grenvillian) Orogeny. AGU Joint Assembly 2009, worth, R.E., Krabbendam, M., & Strachan, R.A. (eds.): Continental ­ Toronto. Abstract GA13A-04. Tectonics and Mountain Building – The Legacy of Peach and Ludwig, K.R. 2003: Isoplot 3.00. Berkeley Geochronology Center Special­ Horne. Geological Society of London Special Publication 335, 715- Publication 4, 70 pp. 737. Menuge, J.F. & Brewer, T.S. 1996: Mesoproterozoic anorogenic mag- Werenskiold, W. 1910: Om Øst-Telemarken. Norges geologiske under- matism in southern Norway. In: Brewer T.S. (Ed.) Precambrian søkelse 52, 69 p. crustal evolution in the North Atlantic regions. Geological Society Wiedenbeck, M., Alle, P., Corfu, F., Griffin, W.L., Meier, M., Oberli, Special Publication 112, 275-295. F., von Quadt, A., Roddick, J.C. & Spiegel, W. 1995: Three natural­ Moecher, D.P. & Samson, S.P. 2006: Differential zircon fertility of zircon standards for U-Th-Pb, Lu-Hf, trace element and REE source terranes and natural bias in the detrital zircon record: Impli- analyses­. Geostandards Newsletter 19, 1-23. cations for sedimentary provenance analysis. Earth and Planetary Wyckoff, D. 1934: Geology of the Mt. Gausta Region in Telemark, Science Letters 247, 252-266. Norway. Norsk Geologisk Tidsskrift 13, 1-72. Morton, A. & Chenery, S. 2009: Detrital rutile geochemistry and thermo­metry as guides to provenance of – sandstones of the Norwegian Sea. Journal of Sedimentary Research 79, 540-553. Nordgulen, Ø. 1999: Geologisk kart over Norge, berggrunnskart (bedrock map) Hamar, 1:250 000. Norges geologiske undersøkelse, Trondheim. Padget, P. & Brekke, H. 1996: Geologisk kart over Norge, berg- grunnskart (bedrock map) Arendal, 1:250 000. Norges geologiske undersøkelse, Trondheim. Patchett, J. & Kouvo, O. 1986: Origin of continental crust of 1.9–1.7 Ga age: Nd isotopes and U-Pb zircon ages in the Svecokarelian terrain ­ of South Finland. Contributions to Mineralogy and Petrology 92, 1-12. Rosa, D.R.N., Finch, A.A., Andersen, T. & Inverno, C.M.C. 2009: U– Pb geochronology and Hf isotope ratios of magmatic zircons from the Iberian Pyrite Belt. Mineralogy and Petrology 95, 47-69. Røhr, T.S., Andersen, T. & Dypvik, H. 2008: Provenance of Lower sediments in the Wandel Sea Basin, North Greenland. Journal of the Geological Society 165, 755-767. Sigmond, E.M.O. 1985: The Mandal-Ustaoset line, a new discovered major fault zone in south Norway. In: Tobi, A.C. & Touret, J.L.R. (eds.): The Deep Proterozoic Crust in the North Atlantic Provinces. NATO Advanced Study Institute Series, Series C 158, 323-330. Sigmond, E.M.O., Gjelle, S. & Solli, A. 1997: The Rjukan Proterozoic rift basin, its basement and cover, volcanic and sedimentary infill, and associated intrusions. Norges geologiske undersøkelse Bulletin 433, 6-7.