| Abstract [eng] |
The theme of Master thesis is “Origin of West Lithuanian geothermal anomaly”. Geothermal anomaly in western part of Lithuania is the most intense in the Eastern Europe Craton that implies exceptional regime in the lithosphere of the region. Inventory of similar heat flow anomalies in the cratons worldwide indicates a strong correlation with age of lithosphere increasing form Archean (41 – 46 mW/m2) to Proterozoic (49 – 54mW/m2). It is related mostly with different amount of heat generating elements in the crust. According to different estimates the mantle heat flux in stable cartons does not exceed above 20-35 mW/m2. Geothermal anomalies observed in stable cratons can be related to several reasons: higher heat flow from mantle, higher concentration of the heat generating elements in the crust, adjective heat transfer along the fault zones. The origin of the geothermal anomaly in west of Lithuania is not completely clear and is still a matter for discussions. This question is not only scientific, it also has a practical background relating to exploration of geothermal resources. The purposes of the study: 1. Inventory of the geothermal anomalies in cratons; 2. Origin of the geothermal anomaly in west Lithuania; 3. Assessment of the crustal and mantle input to the the surface heat flow; 4. Identification of the perspective areas for geothermal energy exploration. According to geothermal modelling the West Lithuanian geothermal anomaly is caused by several factors (1) high heat generation of crustal lithologies and (2) increased heat flow (10-15mW/m2 higher then that in east Lithuania) from the mantle. And input to the total heal flow from the crustal heat generation is about 45mW/m2 in west Lithuania. Higher mantle heat flow can be caused by small-scale mantle flow or enrichment by minerals having increased thermal conductivity in the upper mantle. The alternative geothermal model was also constructed. It shows that 3 µW/m3 of heat generation in the low velocity layer at 10 km depth might be enough to explain high surface heat flow in west Lithuania. Modelling shows that most perspective areas for geothermal exploration where 150°C temperature is less than 5km depth coincides with Žemaičių Naumiestis granitoids and Vilkyčiai areas. |
