Salt tectonics of the Eastern Carpathian Bend Zone, from the folded galleries of the Slănic Prahova salt mine to the Mânzălești diapir, one of the largest rock-salt outcrops in Europe.
The Eastern Carpathian Bend Zone is one of the classic salt-tectonic provinces of Europe, where salt has shaped the fold-and-thrust belt and its hydrocarbon system. This two-day course takes participants from the spectacular folded galleries of a show salt mine to one of Europe's largest rock-salt outcrops, reading salt deformation across a range of scales.
On the first day we descend into the Slănic Prahova salt mine, whose cleaned and lit galleries expose metre-scale isoclinal folds in the mid-Miocene halite. On the second we examine the Mânzălești diapir, a low-angle sheared, decapitated salt body with spectacular salt-karst geomorphology and remarkably fast present-day uplift.
Throughout, we connect what is seen in the field to the structural style of the Bend Zone, to the salt's role in the petroleum system, and to salt research more broadly. Instruction is led by structural geologists whose published research defined the salt structures of the region.
The first stop is at Piatra Verde, where we discuss the stratigraphy of the lower Miocene salt, but also see the gypsum evaporites and their relation to the tuff layer, but the day centres on the Slănic Prahova salt mine. The salt here is also exposed at surface in several locations, but we will go into a gallery system that is closed to extraction but open to visitors. The Unirea mine (mined 1943–1970, base level ~208 m below surface, ceilings some 60–70 m high) reveals metre-scale isoclinally folded halite in grey, white and black colour bands, with boudinaged layers, recording both middle Miocene and Wallachian-phase deformation. We use the mine to understand salt flow and the structure of the Slănic syncline within the Tarcău nappe.
The Mânzălești diapir is one of the largest rock-salt outcrops in Europe, about 2.7 by 1.3 km at surface, above salt whose base lies at roughly 3,500 m. It shows a sub-horizontal foliation with isoclinal folds and low-angle shear zones, interpreted as the sheared, decapitated top of a deep salt-cored structure overridden by the advancing Tarcău nappe. We examine its impure, inclusion-rich halite and its spectacular salt-karst geomorphology and dissolution features and discuss the remarkably fast present-day uplift of the diapir revealed by radiocarbon dating and satellite (PSInSAR) data.
A background in geology or a related geoscience is recommended; the course suits practising professionals and postgraduate students alike, and no prior experience with salt tectonics is required.
The course involves a visit to the Slănic Prahova show mine (reached by stairs or mine transport, with walking over uneven underground floors) and surface fieldwork over uneven terrain at Mânzălești. A reasonable level of fitness is required; the mine is cool year-round, so warm clothing is advised.