Crystalline basement of the Polish part of the Baltic Sea

Wacław Ryka

Abstract


New geophysical data and the results of the petrographic investigation of the rocks derived from boreholes performed in the Polish area of the southern Baltic Sea enabled to compile the schematic geological map of the crystalline basement surface. In the south-western part the basement is probably composed of Presvekofenno-Karelian granitoids whereas in the north-eastern part of rapakiwi-like granitoids. North of Rozewie - Hel Spit the Presvckofenno-Karelian folding zone represented by enderbites and pyroxene gneisses is jutting out into the sea is quite probably that the Polish rapakiwi-like granitoids are southern domain of the Trans-Scandinavian granitic-porphyry belt of southern Sweden. The very young age the Gothian charnockitization, migmatization and anatexis having been hard to justify thus far may be explained by the Halland quasi-orogeny. In turn, the reactivation of the Pregothian meridional faults can be elucidated by the Grenville rotation of the Baltic Shield and its collision with the Laurentian Shield.


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