Distribution of the Transscadinavian Igneous Belt in the Baltic Sea region

• Main Authors: Salin Evgenia, Sundblad Krister
• Other Authors: geologia, Geology, 2606902
• Language: English
• Published: Geological Survey of Finland 2018
• Subjects: Berglund; Hamn; Fennoscandian
• Online Access: https://www.utupub.fi/handle/10024/160527; http://tupa.gtk.fi/julkaisu/erikoisjulkaisu/ej_101.pdf

The Transscandinavian Igneous Belt (TIB) is a major magmatic complex along the western margin of the Svecofennian Domain in the Fennoscandian Shield in which several granitoid generations (TIB 0, TIB 1, TIB 2 and TIB 3) have been recognized (Larson & Berglund 1992). Recent studies have also identified the presence of the 1.77–1.81 Ga TIB 1 generation at several drill sites below the Phanerozoic sedimentary cover in the Baltic Sea region: Kvarne on southernmost Gotland (Sundblad et al. 2003), Böda Hamn and Valsnäs on northern and central Öland, respectively (Salin et al. 2018), as well as E-7, offshore on the Latvian/ Lithuanian border (Salin et al. 2016). In this study, we report U–Pb zircon ages from the Precambrian basement in the Baltic Sea region at two more sites: percussion drilling material from Frigsarve (southern Gotland) and drill core D1-1 from the Lithuanian offshore region. Zircons from Frigsarve yielded a LA-ICP-MS age of 1845 ± 4 Ma, which is comparable with the age of the TIB 0 generation in southeastern Sweden. According to crystal morphology and SIMS ages, the zircons from the D1-1 drill core belong to two generations. The larger zircon grains have an age of 1792 ± 8 Ma, which is similar to the TIB 1 generation. The smaller zircon grains are 1744 ± 7 Ma old and are interpreted to record a later 1.73–.68 Ga high-grade metamorphic event, which is widespread in Western Lithuania (Skridlaite et al. 2014). In conclusion, all data from previous and current studies show that the Transscandinavian Igneous Belt extends over vast areas in the Baltic Sea region, from Öand and southern Gotland to the offshore regions of Latvia and Lithuania.