Chapter 1 Over view

Lithium in pegmatites of the Fennoscandian Shield and operation prospects for the Kolmozero deposit on the Kola Peninsula (Russia)

“…The most significant of them are the Kaustinen and Somero-Tammela, in particular the Kaustinen, which hosts six largest lithium deposits of Finland. The Kaustinen Li-pegmatite province, covering approximately 500 km 2 is located in western Finland within the Palaeoproterozoic supracrustal rocks of the Pohjanmaa schist belt (1.92 Ga), composed dominantly by the mica schists and gneisses intercalated with metavolcanic rocks (Vaasjoki et al 2005; Sarapää et al 2015; Rasilainen et al 2018). The Pohjanmaa schist belt is bordered by Vaasa granitoid complex in the west and the Central Finland granitoid complex in the east.…”

3.1 The Early Palaeoproterozoic of Fennoscandia: Geological and Tectonic Settings

“…Carbonate formations are abundant in southern Finland (K€ ahk€ onen 2005). (Andersson et al 2002), isotopic studies have not revealed any significant Archaean component in the source of igneous rocks of the Svecofennian domain (Vaasjoki et al 2005). However, these studies have indicated that an older Palaeoproterozoic, c. 2100-2000 Ma source component is needed (Lahtinen and Huhma 1997).…”

“…Lahtinen et al (2005Lahtinen et al ( , 2009) have published accounts on the tectonic evolution of the Shield and the reader is referred to these articles for detailed information. It suffices here to list the main Svecofennian orogenic stages as summarized by Lahtinen et al (2005): (1) Vaasjoki et al (2005) stage (1790-1770 Ma). The prolonged accretionary history involving collisions of island arc-microcontinent collages against the Archaean craton resulted in closure of oceanic basins, crustal thickening in the Archaean-Proterozoic boundary zone (currently 65 km), widespread orogenic to post-orogenic plutonism and overthrusting of continental margin sediments and fragments of oceanic crust.…”

“…The prolonged accretionary history involving collisions of island arc-microcontinent collages against the Archaean craton resulted in closure of oceanic basins, crustal thickening in the Archaean-Proterozoic boundary zone (currently 65 km), widespread orogenic to post-orogenic plutonism and overthrusting of continental margin sediments and fragments of oceanic crust. Archaean crust was reactivated (melted) within a distance of 150 km from the collisional zone (Vaasjoki et al 2005) and isotopic resetting of minerals and disturbance of palaeomagnetic signatures due to the thermal effects of the Svecofennian orogenies took place still further inland within the craton.…”