The west Lithuania is prospective for the development of the HDR/EGS geothermal systems. For the planning of the exploration activities it is important to understand the origin of the anomalous heat flow. The recent studies revealed that one of main components of West Lithuanian Geothermal anomaly is the heat generated by granitic plutons intruded as one of last pulses of granitic magmatism at 1.46 Ga in the crust of western margin of East European Craton. Plutons of this generation are known in SW Sweden, on Danish island Bornholm and West Lithuania.
This magmatic pulse is explained by hypothetical Danopolonian orogeny and related crustal deformations. However geochemical composition of plutons suggests their formation rather by melting of cratonic crust, influenced by mantle plume.
Largest of these plutons is Žemaičių Naumiestis (ZN) in West Lithuania, composed by monzo and sienogranites and minor phase of monzodiorite. Geochemical features of these rocks essentialy differ from coeval Swedish plutons and cratonic intrusions in Southern Lithuania. They are mainly ferroan, alkali-calcic and shoshonitic, thus fitting to A-type granites. Same age rocks are dominantly peraluminous and have other features of S-type granites. They are comparatively enriched in K, Th, U, Rb, REE.
These specific features might be explained by source rocks of magma, which presumably derived from metamorphosed pelitic and semipelitic rocks strongly migmatised during the orogenic period and originally enriched in Al, K, REE and other incompatible elements. Such a composition results in a higher heat generation capacity of cratonic granitic rocks.