Petrology and tectonic evolution of the Kiskunhalas-NE fractured hydrocarbon reservoir, South Hungary
Central European Geology
The Kiskunhalas-NE (KIHA-NE) fractured CH-reservoir is part of the structurally rather complex crystalline basement of the Great Hungarian Plain. In course of petrological and thermometric examinations various rock types of the investigated area have been classified and characterized. There are four basic lithological units in the area; in the lowest structural position orthogneiss is common, which according to its petrographic features is assumed to be identical to the orthogneiss body of the
... gneiss body of the adjacent Jánoshalma (JH) basement high (metamorphic peak temperature T < 580°C according to Zachar and M. Tóth, 2004) . The next rock unit upward is the highly mylonitized variety of the orthogneiss bearing textural features suggest deformation in an extensional stress regime. In the higher section of the mylonite zone graphitic gneiss mylonite is characteristic, with a peak metamorphic T of 410±45 °C. The lithology at the shallowest position of the area is a graphitic carbonate phyllite, with a T of 375 ± 15 °C. Estimation of the deformation temperature for both mylonitic rocks results approximately in Tdef ~ 455 °C. All data together suggest that between the top (graphitic carbonate phyllite) and the bottom (orthogneiss) of the ideal rock column there is about 200 °C peak metamorphic temperature deviation. The two extreme metamorphic blocks probably got juxtaposed along an extensional fault zone in the basement at approximately 15 km depth.