Provenance of the North Eastern Carpathian thrust sheet deposits based on geochronology

In the northernmost part of the Romanian Carpathians, the Maramureș region exposes several tectonic units comprising remnants of the Mesozoic Ceahlău - Severin Ocean. The “Black Flysch” unit contains a mafic complex extended in the Middle – Late Jurassic interval. These are covered by Upper Jurassic–Lower Cretaceous sediments, which include deep-water carbonates and siliciclastic deposits in the “Black Flysch” Nappe and mainly turbidites in the Ceahlău unit, which belong to the Outer Dacide nappe system.

The U-Pb age distribution spectra of detrital zircons obtained from the samples collected from the “Black Flysch” and Ceahlău tectonic units exhibit similarities within the range of 180–3,000 Ma. Significant peaks have been noticed at around ~460, 580–620, ~320, 180–200, and 950–1,100 Ma. Within the ‘Black Flysch’ Nappe prevail Ordovician ages (~460 Ma) associated with the Bucovinian Nappe basement. Conversely, in the Ceahlău Nappe, the Late Neoproterozoic peak (~600 Ma) holds greater significance, corresponding to the sediments of the Eastern European Platform and the paragneiss of the Bucovinian Nappe. The East European Craton contributes insignificantly as source area, given the minimal percentage of inherited ages surpassing 1 Ga.