Mesozoic volcano-sedimentary sequences of the S Alps (Dolomites; Middle Triassic) and Carpathians (Jurassic/Cretaceous) – preliminary results of comparative sedimentological studies and their geodynamic significance in geotectonic of the Western Tethys

The geological record of the Alpine belt preserves the whole Permian-Mesozoic history of the Tethys Ocean and constitutes the base for palaeogeographic-geodynamic reconstruction of this ocean. Pre-orogenic period of the... [ view full abstract ]

The geological record of the Alpine belt preserves the whole Permian-Mesozoic history of the Tethys Ocean and constitutes the base for palaeogeographic-geodynamic reconstruction of this ocean. Pre-orogenic period of the Permian-Mesozoic deposits in the Dolomite Mts. documents perfectly a long oceanic history of the central part of the Western Tethys. The Triassic units are tripartite in this mountains, from Werfen-type clastic-carbonate Early Triassic units, through Mid-Triassic carbonate platforms with volcanogenic-carbonate deposits up to Late Triassic prograding and aggrading carbonate platforms.
The Late Anisian–Ladinian Magmatic Cycle, which had produced large amounts of volcano-sedimentary sequences, is a very well documented geodynamic event in the history of the Dolomites and, moreover, of the Alps. Our preliminary recognition of these deposits/units in several places in the Dolomite Mts (syn-volcanic subaqueous deposits - pillow lavas, pyroclastic density current deposits, lahar deposits – and post-volcanic subaqueous deposits – volcaniclastic mass flow deposits) indicates absolutely unique chance to reconstruct these spectacular volcanogenic event(s) and especially in their geodynamic and geotectonic regimes, which are the base to wider palaeogeographical reconstruction of this part of the Western Tethys Ocean. In comparison, in the Carpathians (Ukrainian-Romanian transborder zone) we studied simultaneously very similar, almost identical, the latest Jurassic-earliest Cretaceous volcanogenic-sedimentary units. They are rich in volcanogenic-sedimentary facies including basaltic pillow lava flows, thick sequence of volcanogenic debris flows and pyroclastic flysch distributed along almost 100 km long belt in the eastern Carpathians. Such comparative studies, the most probably of syn-rift in origin sequences, analyzed in different, independent both in space and time selected parts of the Western Tethys, could help to understand similar geodynamic/geotectonic regimes in separated parts of the Tethys Ocean.