Stratigraphy, age, and Sm-Nd isotope systematics of the country rocks to Zn-Pb sulfide deposits, Ammeberg District, Sweden

Mafic plutonic rocks in a continental‐arc setting: geochemistry of 1.87–1.78 Ga rocks from south‐central Sweden and models of their palaeotectonic setting

“…Such 'mildly depleted' initial e Nd values are common for early Svecofennian (c. 1.9 Ga) mafic rocks (e.g. Huhma 1986;Patchett and Kouvo 1986;Patchett et al 1987;Valbracht 1991;Björklund and Claesson 1992;Kumpulainen et al 1996;Makkonen 1996;Vaasjoki and Huhma 1999;Rämö et al 2001;Väisänen et al 2008), and for mafic TIB rocks of all ages, with only a few data reported in the range of þ2 to þ3.5 (Andersson 1997b;Nyström 1999;Claeson and Andersson 2000;Claeson 2001;Larson and Hellström 2003;Wikström and Andersson 2004;Andersson et al 2004bAndersson et al , 2007 including one of our Järna samples at þ2.7. Circa 1.85 Ga mafic rocks of the Ljusdal batholith further north tend to show relatively high e Nd values at c. þ2.6 , and mafic rocks with MORB affinities, locally associated with the c. 1.83 Ga Oskarshamn-Jönköping Belt (OJB) in SE Sweden, are strongly depleted (Figure 10; Mansfeld et al 2005).…”

“…Evolution field for the Archaean crust as compiled in Andersson et al (2002). DM, depleted mantle (DePaolo 1981); CHUR, chondritic uniform reservoir; ESF, early Svecofennian felsic crust in the southern Svecofennian province (Huhma 1986;Patchett and Kouvo 1986;Patchett et al 1987;Valbracht 1991;Kumpulainen et al 1996;Andersson 1997b;Lahtinen and Huhma 1997;Rämö et al 2001); ESB, early Svecofennian basic rocks in the southern Svecofennian province (Huhma 1986;Patchett and Kouvo 1986;Patchett et al 1987;Valbracht 1991;Björklund and Claesson 1992;Kumpulainen et al 1996;Makkonen 1996;Vaasjoki and Huhma 1999;Rämö et al 2001); Sed., early Svecofennian metasedimentary rocks in the southern Svecofennian province (Miller et al 1986;Huhma 1987;Patchett et al 1987;Valbracht 1991;Kumpulainen et al 1996;Andersson 1997b;Claeson and Andersson 2000;Lahtinen et al 2002). The bars with vertical ruling (mafic rocks) and white bars (felsic rocks) comprise: c. (Wilson et al 1985;Patchett et al 1987;Heim et al 1996;Lundqvist and Persson 1999;Nyström 1999); c. 1.7 Ga mafic TIB-2&3 rocks (Wilson et al 1985;Nyström 1999;Claeson 2001); post-tectonic mafic dykes and intrusives, post-dating TIB: rapakivi-related dolerites, SE Finland (Rämö 1991), SW Finland (Rämö 1991;…”

Granitic magmatism by melting of juvenile continental crust: new constraints on the source of Palaeoproterozoic granitoids in Fennoscandia from Hf isotopes in zircon

“…Patchett & Kuovo 1986;Patchett et al 1987;Valbracht et al 1994;Claesson & Lundqvist 1995;Lahtinen & Huhma 1997;Andersson et al 2002Andersson et al , 2008; (2) the frequent occurrence of 2.1-1.90 Ga inherited zircons and the scarcity of 2.45-2.1 Ga zircon in Svecofennian metasedimentary and metaigneous rocks (e.g. Claesson et al 1993;Kumpulainen et al 1996;Lahtinen et al 2002;Ehlers et al 2004;Sultan et al 2005;Andersson et al 2006a;Bergman et al 2008); (3) the bimodal, felsic-mafic character of the 1.91-1.86 Ga magmatism, implying a preexisting crust (e.g. Baker et al 1988;Lagerblad 1988;Gaál 1990;Allen et al 1996); (4) the presence of a few outcropping 1.95-1.91 Ga igneous rocks (e.g.…”

The sub‐Jotnian strömsbro granite complex at gävle, Sweden

“…Unless enriched mantle sources are invoked, the dolerite magma must have assimilated a significant portion of Archaean source material to obtain this low value, however slightly less than in the cases of the other complexes in central Sweden (Andersson 1996a). An enriched mantle at 1.50 Ga is not favoured by the fact that neither in the earlier, early Svecofennian (1.95-1.86 Ga) and Transscandinavian igneous belt (1.85-1.65 Ga), nor in the later post-Jotnian (c. 1.26 Ga) suites do isotopically enriched basic rocks occur (Huhma 1986;Claesson 1987;Patchett et al 1987Patchett et al , 1994Rämö 1990;Valbracht 1991;Björklund & Claesson 1992;Kumpulainen et al 1996;Andersson in prep.). These basic rocks are isotopically mildly to strongly depleted.…”