Critical Tectonic Limits for Geothermal Aquifer Use: Case Study from the East Slovakian Basin Rim

Abstract

The Pannonian basin is a major geothermal heat system in Central Europe. Its peripheral basin, the East Slovakian basin, is an example of a geothermal structure with a linear, directed heat flow ranging from 90 to 100 mW/m2 from west to east. However, the use of the geothermal source is limited by several critical tectono-geologic factors: (a) Tectonics, and the associated disintegration of the aquifer block by multiple deformations during the pre-Paleogene, mainly Miocene, period. The main discontinuities of NW-SE and N-S direction negatively affect the permeability of the aquifer environment. For utilization, minor NE-SW dilatation open fractures are important, which have been developed by sinistral transtension on N–S faults and accelerated normal movements to the southeast. (b) Hydrogeologically, the geothermal structure is accommodated by three water types, namely, Na-HCO3 with 10.9 g·L−1 mineralization (in the north), the Ca-Mg-HCO3 with 0.5–4.5 g·L−1 mineralization (in the west), and Na-Cl water type containing 26.8–33.4 g·L−1 mineralization (in the southwest). The chemical composition of the water is influenced by the Middle Triassic dolomite aquifer, as well as by infiltration of saline solutions and meteoric waters along with open fractures/faults. (c) Geothermally anomalous heat flow of 123–129 °C with 170 L/s total flow near the Slanské vchy volcanic chain seems to be the perspective for heat production.

Structural conditions for relay ramp fault development on the edge of the collision wedge: a case study from the East Slovak Basin

“…The axes of the main distribution channels are oriented parallel to the direction of the fault networks and change position depending on the amount of increasing subsidence. The most striking changes are connected to breaching, which generated perpendicular NE-SW extensional faults, that were later used as pathways for fluid migration [Jacko et al, 2021a]. This is supported by current geothermal exploration in the area.…”

“…Additionally Spontaneous Potential (SP) responses were used and were compared to seismic reflectors [Jacko in Žec et al, 1997, pp. 1-254;Jacko in Hrušecký et al, 2000;Jacko in Sály et al, 2006, Pachocka et al, 2010, 62 p;Jacko in Fričovský et al, 2012, Jacko et al, 2014, 2021a.…”

“…Here, maximal thermal flow isolines (which are linked to the parts of the region with the thinnest crust) are spatially controlled by two NW-SE and N-S dominating fault sets. It is worth mentioning that the max.-e.g., 120 °C thermal flow isoline, located at the connecting point of the N-S and the NE-SW faults, has an opposite-NW-SE course [Jacko et al, 2021a].…”

The Use of Multi-Geophysical Methods to Determine the Geothermal Potential: A Case Study from the Humenné Unit (The Eastern Slovak Basin)

“…The tectonic inversion changed the surface relief, and thus controlled the gravity-driven flow systems in the basin fill. The Pannonian basin's heat flow value ranges from 50 to 130 mW•m −2 , and its mean value is about 100 mW•m −2 [6,10]. The temperature gradient varies between 40 and 50 K/km in the upper 5 km [11].…”

Geothermal potential and genetic mechanisms of the geothermal system in the mountainous area on the northern margin of north china

“…Geothermal resources as renewable energy with enormous potential have received significant attention worldwide in recent years, especially under the goal of diminishing carbon dioxide emissions (Gao et al, 2021;Jacko et al, 2021). North China is a densely populated area that has suffered from severe air pollution (Liu et al, 2020;Poon et al, 2006), thus substantial demand for clean energies exists.…”