Groundwater flow system understanding of the lukewarm springs in Kistapolca (South Hungary) and its relevance to hypogene cave formation

Abstract

Springs have an important role both in groundwater flow system understanding and in maintaining groundwater-related ecosystems. The aim of the research of the lukewarm karst springs in Kistapolca is to understand the origin of the elevated temperature (22-24 °C), i.e., whether it is the result of mixing of cold and thermal waters or it represents the terminal area of intermediate flow systems. This question has also an important relevance to the evaluation of recent cave formation in the area. In case of mixing of different waters dissolution by mixing corrosion could take place. This scenario was proposed for the formation of the Beremend Cave, which is situated in the close vicinity of the springs, and which is the only known cave of the area, where the passages are partly filled by water. Therefore, several methods, including geophysical, geochemical and stable isotope measurements, evaluation of continuous-time series of water level change, temperature, and electrical conductivity data and hydraulic evaluation of vertical flow conditions by pressure-elevation profiles were combined in order to acquire information about the hydrogeological environment and flow conditions in the area. The results show that a higher order flow system derived from the Villány Hills feeds the springs in Kistapolca without significant local influence. In addition, the results related to the Beremend Cave indicate that cave formation by mixing corrosion is not an active process today in the area, the cave is rather influenced by local processes.

Characterization of the regional groundwater flow systems in south Transdanubia (Hungary) to understand karst evolution and development of hydrocarbon and geothermal resources

“…As direct recharge through the uncovered hilly ranges became more and more pronounced, the fraction of basinal fluids decreased, the caves were flooded by "fresh" waters, and the thermal-water-related hypogene cave formation period stopped, also because some of the caves were disconnected from the water table due to ongoing uplift. This scenario is supported by recent isotope measurements from the cave-filling waters of the Beremend Cave, which showed similar values to the present-day precipitation (Erőss et al 2020).…”

Multi-method geochemical characterization of groundwater from a hypogene karst system

“…The approach in many of these examples involves using a relatively high number of sampling locations and/or time series of certain geochemical parameters covering longer periods (e.g. Bayari et al 2009a, b;Erőss et al 2020;Galdenzi et al 2008;Mádl-Szőnyi and Tóth 2015). Spring waters often provide the main insight into the geochemical properties of these hypogene karst groundwater systems (e.g.…”

Plio-Pleistocene Dust Traps on Paleokarst Surfaces: A Case Study From the Carpathian Basin

“…This carbonate rock suite (Nagyharsány Limestone) is a 400-500 m thick Urgon facies limestone (Császár, 2002). The karst processes of the area are described in detail by Erőss et al (2020).…”

“…Although, it has already shown that the red clay sediments in karstified fissures are wind-blow in origin, but the whole processes require more observations due to the karst environment. Hypogene karstification has been reported from Hungary (Leél-Ossy, 2017; Mádl-Szonyi et al, 2017) and Zrn, zircon; Grt, garnet; Ap, apatite; Ttn, titanite; Rt, rutile; Am, amphibole; Px, pyroxene; Tur, tourmaline; Ky, kyanite; St, staurolite; Ep, epidote; Mnz, monazite; Crn, corundum; Spl, spinel. especially from the region of Beremend (Erőss et al, 2020). It is important to be able to distinguish between allochthonous fissure filling sediments and ghost-rock (Dubois et al, 2014;Osborne, 2017; in-situ weathered rock, also called phantom rock).…”