The Geology of the Luhačovice Springs: A Prehistoric Sea Beneath the White Carpathians

Beneath the Luhačovice valley lies a geological history dating back tens of millions of years. The local mineral springs did not form through rainwater seeping through rock—as is the case with most mineral waters around the world. They are metamorphosed remnants of a prehistoric sea, trapped between layers of rock and enriched over millions of years by deep-seated gases and minerals. This exceptional origin makes Luhačovice’s waters unique in the world.

The Tethys Sea: 100–20 million years ago

From the Late Cretaceous to the Paleogene (roughly 100 to 20 million years ago), the vast Tethys Sea covered the area of present-day Central Europe. This warm oceanic environment left a huge amount of sediment on the seabed—sand, clay, limestone, and organic material. Through gradual tectonic movement, the Tethys seafloor became folded and uplifted. However, the seawater did not remain merely a memory—some of it remained trapped between impermeable layers of rock as a fossil remnant of the long-vanished ocean.

The Flysch Belt of the Western Carpathians

The rocks in which the Luhačovice springs are hidden belong to the flysch zone of the Western Carpathians. Flysch is characterized by alternating layers of sandstone and mudstone—soft and hard rocks—formed by the deposition of marine sediments. This geological zone stretches in an arc from Vienna through southern Moravia, the White Carpathians, and the Beskids to the Polish Carpathians and on to Ukraine.

It is precisely within these flysch rocks—specifically in the Paleogene sandstones and mudstones—that fossil seawater remains trapped to this day, forming the basis of all of Luhačovice’s springs. Its age is estimated to be tens of millions of years.

How minerals get into the water

The composition of Luhačovice’s waters is the result of three processes that have been occurring for millions of years:

1. NaCl from marine sediments — the basis of the salty taste comes directly from fossil seawater. The original seawater had a mineralization of around 35 g/l (pure NaCl). Dilution by groundwater and enrichment with other components resulted in the current composition with a mineralization of 9–16 g/l.
2. CO₂ from the deep Earth’s mantle — carbon dioxide rises from great depths of the Earth’s crust along tectonic faults. This juvenile (deep) CO₂ is the driving force behind the entire system — it acidifies the fossil water, which then dissolves the surrounding rocks.
3. Iodine and bromine from organic sediments — the presence of iodine in such high concentrations is rare in non-petroleum waters. The waters of Luhačovice draw iodine from organic residues deposited on the bottom of a prehistoric sea — from so-called petroleum domes. This theory was confirmed by Associate Professor Václav Zýka as early as 1957.

Other components obtained through contact with flysch rocks include lithium, barium, boron, fluorine, and strontium—trace elements that give Luhačovice waters their specific healing properties.

The Nezdenice Fault: A Gateway from the Depths

The Luhačovice area is located on a prominent anticline with its axis in the valley of the Luhačovice Stream (Šťávnice / Horní Olšavy). This fold is disrupted by a system of tectonic faults, the most significant of which is the Nezdenice Fault, stretching from Biskupice to Březová pod Lopeníkem.

The Nezdenice Fault acts as the main pathway for deep CO₂ to rise from the mantle into the spring structure. Without this fault, the springs would likely not exist—it is precisely the intrusion of deep gases along the fault line that drives the entire hydrogeological system and allows the mineral water to rise to the surface (source: Girgel, Hrabec, Šnajdara, 2008).

Why are the springs cold?

The Luhačovice springs have a temperature of only 10–14 °C, which is surprising at first glance for water originating from great depths. The explanation lies in their origin: unlike volcanic thermal springs (where the water is heated by magma), the Luhačovice waters are driven by the pressure of deep CO₂, not by heat. Fossil seawater rises to the surface along faults but does not come into contact with volcanically heated rocks.

This mechanism is characteristic of the entire Carpathian flysch zone—cold, highly mineralized mineral waters saturated with CO₂ can be found from Luhačovice through Korytnica in Slovakia and Krynica-Zdrój in Poland all the way to Truskavets in Ukraine.

Geological counterparts: Krynica and Muszyna

The closest geological relatives of the Luhačovice springs are the mineral waters in Krynica-Zdrój and Muszyna, Poland, located about 200 km to the east. Both locations lie within the same Magura Flysch Belt—they are thus literally geological siblings with the same type of rock, the same mechanism of water formation, and the same fossil marine origin.

The Krynica spring Zuber No. 2, with a mineralization of 22,000 mg/l, is even stronger than the most concentrated spring in Luhačovice, Elektra (16,456 mg/l). Both spas share the HCO₃-Cl-Na hydrochemical type, the presence of iodine, and natural CO₂ saturation. Historically, Krynica and Luhačovice were part of the same Austro-Hungarian spa circuit.

Geological uniqueness in numbers

A total of 15 natural healing springs emerge in the Luhačovice area, 13 of which are actively utilized. All share common parameters: the HCO₃-Cl-Na type, a temperature of 10–14 °C, mineralization of 9,000–16,456 mg/l, and natural CO₂ saturation at a concentration of 2,000–3,100 mg/l. The combination of fossil marine origin, cold temperature, high mineralization, iodine, lithium, barium, and boron is exceptionally rare on a global scale.

A detailed analysis of individual springs can be found on the websites for Vincentka, Ottovka, Aloiska, and Dr. Šťastný’s Spring, as well as in the complete overview of springs.

Sources: GeoERA (2021): Luhačovice Mineral Springs; Girgel M., Hrabec J., Šnajdara P. (2008): Mineral Springs of the Zlín Region; Janoška M. (2011): Mineral Springs in Bohemia, Moravia, and Silesia; Zádrapa L. (2014): master’s thesis, theses.cz/id/rlg98y. See also Wikipedia: flysch, Tethys, White Carpathians, hydrogeology.