Characterisation of Na-metasomatism in the Sveconorwegian Bamble Sector of South Norway

Dynamic Metasomatism: Stable Isotopes, Fluid Evolution, and Deformation of Albitite and Scapolite Metagabbro (Bamble Lithotectonic Domain, South Norway)

“…Na-metasomatism in the form of albitisation is regionally extensive in the Precambrian crust of southern Scandinavia and is particularly widespread in the Bamble and KongsbergModum lithotectonic domains and the Norwegian part of the Mylonite Zone (Figure 1(a)) [23]. In the Bamble lithotectonic domain, albitisation is present from the northeastern boundary to the Oslo Rift and southwestwards through the domain.…”

“…In the Bamble lithotectonic domain, albitisation is present from the northeastern boundary to the Oslo Rift and southwestwards through the domain. Large bodies of albitite are found in the vicinity of Kragerø and towards Arendal [23,[57][58][59]. Mg-Cl-metasomatised rocks in the form of scapolite metagabbros occur widespread as part of the mapped amphibolites and metagabbro, commonly in conjunction with the albitites [19,20,50].…”

“…In the Kragerø area, MgCl-metasomatised scapolite-bearing rocks occur widespread as a part of the mapped amphibolite, metagabbro, and gabbro lithologies [19,20,23] and have been studied in detail at Ødegården Verk, Ringsjø,Åtangen, Valberg, and Langøy localities (Figure 1(b)). At Langøy and Ødegården Verk, transformation of pristine gabbro to scapolite metagabbro is observed along fluid fronts (Figure 2(a)).…”

“…Subsequently, albitisation transformed scapolite metagabbro and regionally distributed mafic and granitoid rocks to albitites, dominated by albite, with varying amounts of rutile, carbonate, chlorite, and locally prehnite, pumpellyite, and analcime. Albitisation is widespread in the Mesoproterozoic rocks of the Sveconorwegian orogen in southern Scandinavia ( Figure 1) [18,21,23]. In addition, the Bamble and KongsbergModum lithotectonic domains are characterised by a high density of mineral deposits including the common occurrence of apatite and rutile deposits [23,24] and a high density of hydrothermal Fe-deposits including veins and breccias of nickeliferous pyrrhotite-apatite, magnetite-apatite, magnetite and hematite, and Fe-oxide skarn deposits [25,26].…”

“…While the scapolitisation process with respect to mineral reactions is relatively well understood in the Kragerø region, albitisation is a more complex process and less constrained. Extensive albitisation is seen along veins, as brecciation, as formation of foliated albititic felsites and chlorite schists, as carbonate-rich albitite, and as large-scale albitite bodies [23,35].…”