Saulius Šliaupa

Geological Evolution and Resources of the Baltic Sea Area from the Precambrian to the Quaternary

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 collision 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 Rugen 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 reactivation 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 morphological structures are mainly passive features related to selective glacial erosion, but some hints for neotectonic activities do also exist. Glacial erosional processes undoubtedly contributed to the shape and depth of the Baltic Sea. Evidences available today, however, suggest the existence of a pre-existing tectonic depression. Major resources of the deeper underground of the Baltic basin are oil, gas, geothermal energy and reservoir formations which can be used as storage sites (natural gas, CO2, compressed air). Location of known oil and gas fields shows a strong relation to the major fault zones.

Lack of inhibiting effect of oil emplacement on quartz cementation: Evidence from Cambrian reservoir sandstones, Paleozoic Baltic Basin

Currently, the question of whether or not the presence of oil in sandstone inhibits quartz cementation and preserves porosity is still debated. Data from a number of Cambrian sandstone oil fields and dry fields have been studied to determine the effects of oil emplacement on quartz cementation. The data show that the porosity distribution is not affected by the presence of oil in sandstones from oil fields and dry fields with similar porosity distribution. From this, it can be concluded that oil emplacement does not lead to preservation of primary porosity, and silica supply for quartz cementation is derived from internal sources. Rather, in spite of large variation in porosity and quartz cement content, a regular pattern of porosity decrease is related to increasing temperature or depth. The observed heterogeneity is due to local factors that influence the precipitation of quartz cement, including sandstone architecture, i.e., distribution of shales within the sandstone bodies, and sandstone thickness. Heterogeneity is inherent to sandstone architecture and to the fact that silica for quartz cementation is derived from heterogeneously distributed local pressure solution. Models predicting reservoir properties should encompass facies and architecture as important independent factors.

Geodetic network deformation based on GPS data in the Baltic region

Abstract For investigating horizontal deformations of geodetic networks, the data of GPS measurements of the epochs about 1992 and 2003 were used. To avoid the impact of the discrepancy of the systems of coordinates upon the parameters of the deformations, the method of tensor analysis was applied using the method of finite elements. A geodetic network consists of 19 triangles; 15 geodetic ground benchmarks observed by GPS method were used. The horizontal deformations of geodetic network in the territory of the Baltic Sea region were calculated. The maximum relative strain in the territory of the Baltic Sea region varies between +0,03×10–6 and +0,58×10–6 and is positive within the whole territory; the minimum relative strain varies between –0,93× 10–6 and +0,03× 10–6; and the dilatation varies between –0,35×10–6 and +0,16×10–6.

Naujas lietuvos teritorijos vertikaliuju žemes plutos judesiu žemelapis

Santrauka Sudarytas naujas Lietuvos teritorijos dabartiniu vertikaliuju Žemes plutos judesiu greiciu žeme ‐ lapis, judesiams modeliuoti taikant autoriu pasiūlyta metodika. Metodika pagrista vertikaliuju judesiu reiksmiu ir teritorijos svarbiausiu georodikliu koreliacinemis ir regresinemis priklausomybemis, gautomis atlikus geodezinius matavimus. Dabartiniai vertikaliuju Žemes plutos judesiu greiciai Lietuvos teritorijoje yra nuo –3,5 iki +2,5 mm per metus. Intensyviausias Žemes plutos kilimas ir didžiausia judesiu greiciu gradientu kaita yra siaures rytineje Lie – tuvos dalyje, o grimzdimas – pietineje ir pietvakarineje srityse. Istirtas pagal regresini matematini modeli sudaryto emelapio patikimumas ir nustatyta, kad žemelapio atitikimo pagal geodeziniu matavimu rezultatus tikimybe yra ne mažesne nei 0,95.

The Dispersion of Horizontal Tectonic Stresses in the Earth's Crust in the Baltic Region

Abstract GPS measurements recorded within the period from1992 to 2003 were employed to investigate horizontal tectonic stresses in the Earths crust in the Baltic region. To avoid the impact of discrepancies in the systems of coordinates upon the parameters of deformations, the method of tensor analysis was applied thus estimating parameters employing the method of finite elements. Computations were performed using the created algorithms and applying ANSYS code. The values of tectonic stresses in the Earths crust in the territory of the Baltic Sea region were calculated considering changes in maximum and minimum principal stresses. The value of change in maximum principal stress in the territory of the Baltic Sea region varies between –0.0013 MPa and +0.0032 MPa; the value of change in minimum principal stress varies between –0.0084 MPa and +0.0009 MPa. Positive values are dominating in directions of changes in maximum principal stresses (extension), whereas negative values – in directions of changes in ...

Integrated Approach and Application of Gis for Management of Geological Data

Information technology is increasingly used in geological studies and has significantly changed the approach to the compilation of the geological maps, access to and dissemination of study results, and application of the geological data by non-geologist users. The basic concepts of the Information Infrastructure of the Lithuanian Geological Survey consist of the following: (1) integrity of the geological data, as all available information is stored, used, and accessed via central applications; (2) extensive application of geographic information systems (GIS) technology; and, (3) easy access to the database for the global user, which ensures wider application of the geological information.