Geoscience Reference
In-Depth Information
Chapter 2
Geological Evolution and Resources of the Baltic
Sea Area from the Precambrian
to the Quaternary
Saulius Šliaupa and Peer Hoth
Abstract
The Baltic Sea is a young geomorphologic feature that formed during
Quaternary time. It covers the western and the central part of the Baltic sedimentary
basin. The origin of the Baltic Sea and of the corresponding morphological low is
still controversial, considered by some as an erosional structure and as a tectonic
depression by others. The chapter gives a summary of the evolution and the known
resources of the Baltic sedimentary basin focussing on its central part and thus tries
to present new evidence for the origin of the Baltic Sea. The Baltic sedimentary
basin was formed during Late Ediacaran-Early Cambrian time. Its formation was
caused by the reactivation of the weakest lithospheric part of the East European
craton. All the following stages of pronounced basin subsidence (major subsidence
phase during Late Ordovician-Middle Silurian), including the recent tectonic stage,
were dominated by extensional tectonics. However, the most intense structuring of
the crust in the region took place in a compressional setting during Late Silurian and
Early Devonian time. The NW-SE-directed compression was caused by the colli-
sion of Laurentia and Baltica. It caused the formation of an Early Palaeozoic thrust
and fold belt at the margin of the East European craton and led to the formation of
E-W and NE-SW striking faults in the Baltic basin northeast of the Danish-North
German-Polish Caledonides during that time. Typical for the Permocarboniferous
period are magmatic intrusions in the southern part of the Baltic Sea, in northern
Poland, and in the area of the Rügen Island. Tectonic activities ceased within the
Permian and only small amplitude faulting is detected in the Mesozoic. Later on,
tectonic activities increased during the Cretaceous inversion in the southwestern
part of the basin. The typical wrench-dominated faulting is related to the reactiva-
tion of Pre-Permian fault systems by Late Cretaceous inversions of the Mesozoic
Danish and Polish basins. Large-scale ancient structures of the Baltic basin are
reflected in the sea bottom morphology. Detailed analysis indicates that those mor-
phological structures are mainly passive features related to selective glacial erosion,
