Carmen Gaina (CEED director) and Valentina Magni (CEED researcher), were invited by the In Context programme to visit Slănic Moldova in September of this year. This small town of Romania is located in the south-east part of the Carpathian mountains. Tourists come here for its mineral water springs, artists come here to be inspired by its nature, and we came here to talk to high school students about geology, plate tectonics, and the environment. And as an extra perk for us, we also got to explore the surroundings and look at the geology of the region.
The Carpathians are a relatively young mountain chain that formed as a continuation of the Alps due to subduction of a small ocean basin. As this plate sank into the Earth’s mantle, it released water, creating the perfect conditions for the mantle above it to melt, rise at the surface, and form new volcanoes [see CEED's Water Planet - Water and Volcanism initiative]. Subduction and generation of new volcanism migrated progressively towards South-East, where a small part of the slab is still present at depth and where volcanic activity at the surface is very recent (up to 200 000 years ago). Slănic Moldova is at the northern edge of this slab remnant in the accretionary prism of the Carpathian mountains. Walking around this region you can often find layers of sediments that have been tilted and deformed during nappes formation.
The recent tectonic and volcanic history is tightly linked to the presence of large salt diapirs (like that of Târgu Ocna Salina) and numerous mineral water springs. These waters have different characteristics depending on what the host rock they travel through and dissolve is; some are more salty, others are more metallic, a handful have that rotten egg smell typical of sulphur, and others can even be set on fire. But more importantly, they all have healing properties. The Târgu Ocna Salina is also used for curative purposes by people with respiratory problems. Here, salt is extracted for commercial use, but when you go down 8 floors and 240 m you find yourself in a large playground where you can drive a kart, play basketball, volleyball, football, table tennis, chess, and just relax while breathing air that is good for you.
From a geological perspective, this region is a great place to study how the solid Earth interacts with water at different depths and time scales.