Geological Evolution and Resources of the Baltic Sea Area from the Precambrian to the Quaternary - The Baltic Sea Basin - page 37

Intensive glacial erosion led to thickness reduction of the Quaternary cover in the
Baltic Sea area. Therefore it is difficult to reconstruct the successive events during
the Pleistocene. At the beginning of the Pleistocene, the Baltic Sea low was occupied
by the so-called Baltic stream, flowing from northeast towards southwest (Gibbard
1988 ) . The knowledge about the Baltic stream is very limited, because the Elsterian
ice sheet removed all older sediments.
The first ubiquitous evidences for the existence of the Baltic Sea low are marine
sediments of the Holstein interglacial that are distributed in the Baltic Sea area
and adjacent regions (Marks and Pavlovskaya 2003 ) . The second marine event took
place in the Eemian interglacial and the limits of the marine basin roughly coincided
with the present-day Baltic Sea shoreline.
2.7 Geological Resources
Besides drinking waters, sand and gravel deposits (Harff et al. 2004 , Kramarska
et al. 2004 ) are the main resources of the shallow subsurface. The mining of amber is
of additional importance. It is exploited in the Sambia Peninsula (Kharin et al. 2004 )
and prospects are considered in the Polish coastal zone (Kosmowska-Ceranowicz
2004 ) . A small amber exploitation was performed in the Kursiai lagoon during the
previous century.
Important resources of the deeper underground of the Baltic basin are related to
reservoir horizons and hydrocarbon fields. Oil exploitation was initiated in the area
at Kinnekulleverken on Gotland in the 1940s of the previous century (Johansson
et al. 1943 ) . The offshore hydrocarbon exploitation started in the Polish economic
zone in the 1980s and a decade earlier in the onshore area of Lithuania and the
Kaliningrad district.
Reservoir horizons are of importance for gas storage and for geothermal energy
recovery. Additional future utilization of reservoir rocks might be connected to the
issues of CO 2 storage (Šliaupa et al. 2008 ) and the storage of compressed air as an
energy storage option for wind power stations. Major reservoir horizons for all these
utilizations are sandstone layers within the Devonian and the Cambrian. The recov-
ery of geothermal energy from the corresponding formation waters of the reservoir
horizons requires certain temperature levels. The 40 ◦ C level is only reached in cer-
tain areas of the Baltic basin, where the reservoirs are located in a depth below 1,000
m. Perspective areas exist particularly near the Lithuanian coast because of the heat
flow anomaly in this area. So far only the station in Klaipeda produces geothermal
energy on a larger scale in the area (Radeckas and Lukosevicius 2000 ) .
2.7.1 Hydrocarbon Fields
The Baltic basin represents a proven hydrocarbon province (Fig. 2.17 ) . In total
about 40 hydrocarbon accumulations have been discovered (Brangulis et al. 1993 ,