Palaeoproterozoic Continental MORB-type Tholeiites in the Karelian Craton: Petrology, Geochronology, and Tectonic Setting

Geochronology of the Palaeoproterozoic Kautokeino Greenstone Belt, Finnmark, Norway: Tectonic implications in a Fennoscandia context

“…It is characterised by an initial e Nd value of +2.5 ± 1.0 defined by 23 analyses from 6 localities spread over more than 500 km ( Fig. 6; Stepanova et al, 2014). Both the geochemical properties and Nd isotopic signature are remarkably uniform for this dyke suite, and also they are remarkably similar to the ones of the Čáskejas Formation (e Nd = +2.2; Figs.…”

“…With an age of c. 2137 Ma, the Čáskejas Formation is coeval with a suite of mafic dykes intruding Archaean complexes of the Karelian Craton in Finland and Russia, dated between 2140 ± 3 and 2126 ± 5 Ma (zircon U-Pb data; Stepanova et al, 2014). This dyke suite is not voluminous but it is extensive geographically.…”

“…The large uncertainty on the Sm-Nd errorchron is a consequence of the low spread of the Sm/Nd ratio (0.156< (Solli, unpublished data), c. 2137Ma Čáskejas Formation in the Kautokeino Greenstone Belt (data of Sandstad, 1984Krill et al, 1985), c. 2146 Ma Kvenvik Formation in the AltaKvaenangen Tectonic Window (data of Bergh & Torske, 1988;Melezhik et al, 2015aMelezhik et al, ) and c. 2140Melezhik et al, -2126 Ma mafic dykes in the Karelian Craton in Finland and Russia (data of Stepanova et al, 2014) (Boynton, 1984). For the Čáskejas Formation, analyses of elements between Gd and Tm are below the detection limit.…”

“…It exhibits a continental tholeiitic signature, generally lacking LREE enrichment ( Fig. 9; Stepanova et al, 2014). It is characterised by an initial e Nd value of +2.5 ± 1.0 defined by 23 analyses from 6 localities spread over more than 500 km ( Fig.…”

“…9A, B). Rare-earth (Balashov et al, 1993(Balashov et al, ), c. 2450 Ma plutons from the Belomorian Craton (Lobach-Zhuchenko et al, 1998), c. 2450-2428 Ma plutons from the Karelian Craton (Huhma et al, 1990;Amelin & Semenov, 1996;Perttunen & Vaasjoki, 2001;Hanski et al, 2001bHanski et al, ), c. 2450Hanski et al, -2410 Ma volcanic rocks from Vetreny Belt (Puchtel et al, 1996(Puchtel et al, , 1997(Puchtel et al, ), c. 2440 Onkamo Group volcanic rocks (Hanski & Huhma, 2005), c. 2403 Ma Ringvassøy dykes (Kullerud et al, 2006(Kullerud et al, ), c. 2504(Kullerud et al, , 2450(Kullerud et al, , 2310(Kullerud et al, and 2140 Ma dykes in the Karelian Craton (Amelin & Semenov, 1996;Mertanen et al, 2006;Stepanova et al, 2014Stepanova et al, , 2015, c. 2330 Ma Runkaus volcanic rocks in Peräpohja Schist Belt (Huhma et al, 1990), c. 2220 Ma Haaskalehto-type sills and dykes (Huhma et al, 1990;Hanski et al, 2010), 2137 ± 5 Ma amphibolite of Čáskejas Formation (deep pink; Krill et al, 1985) and davidite of the Bidjovagge deposit (pale pink; Bjørlykke et al, 1990) in the Kautokeino Greenstone Belt, c. 2090 Ma Jouttiaapa volcanic rocks in Peräpohja Schist Belt (Huhma et al, 1990(Huhma et al, ), c. 2085 Ma komatiites in the Karasjok Greenstone Belt (Henriksen, 1983;Krill et al, 1985), c. 2060 Ma Siilinjärvi volcanic rocks (Lahtinen et al, 2015b), c. 2060Ma Jeesiörova and Peuramaa komatiites in Savukoski Group in Central Lapland Greenstone Belt (Hanski et a...…”