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Geothermal Rock Conditions and Tectonostratigraphic Relations: Causes, Implications and Consequences

As a principal criterion in evaluation of geothermal rock conditions of Dinarides, it is necessary to know geodynamic evolution processes of particular area during the Earth history. According to this, recent state of the rocks could be described as a consequence of geodynamic evolution. In geologic sense, Dinarides are the relict of ancient Adriatic-Dinaridic Carbonate Platform (ADCP), which represents relatively large carbonate body formed by deposition of tremendous quantities of carbonate materials. This process started before 210 Ma in Upper Triassic, and ends in Middle Eocene Bottom of that carbonate body, is lithologically characterized by Lower Triasssic (Scitian) clastic rocks, while the top is overlained by flysh deposits of Middle Eocene (Lower Lutetian). The series of relatively homogenous sediments, between these two chronostratigraphically very distant horizons of relatively non-carbonate litology is composed from limestones and dolomites. Beside these sediments, there were some episodes of intraplatform non-carbonate sediment deposition, especially anhydrites. Intensive tectonic episodes, such was Laramian tectonic phase, in Early Paleogene caused disintegration of ADCP by intensive tectonic activities. Such whole system is in geothermal point of view, as well as in hydrocarbon potentiality very complex, due to its emphasized anisotropy. In such media rocks forming potentially geothermal reservoirs and theirs neighborhood areas are genetically in very tight relations to tectonostratigraphy and geometry, during the time when they were formed. In this sense, geothermal gradient in general depends from lithology and physical parameters such as porosity, permeability, granulometry, chemical composition of rock forming minerals, and depth. Therefore whole Platform could be observed from two points of view. In costal area geothermal gradient amounts 1, 5 ° C/100 m, while in the sub sea platform area it amounts 2, 5 ° C/100 m, in comparation with Pannonian Basin where the gradient is much higher (4, 5 to 5, 5 ° C/100 m) due to different lithology. Assessment of hydrocarbon reservoirs depends on mentioned number of strictly interrelated factors. They are forming a group of naturally limited geological processes characteristic by their specific activity.

Geothermal rock conditions; Dinarides; Tectonostratigraphy; Adriatic-Dinaridic Carbonate Platform

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