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The Quaternary Persani volcanic field (PVF) consists of alkali basalts formed in an extensional basin at the SE end of the Transylvanian basin, near an important anomaly in the European mantle, the Vrancea slab, a seismically active near-vertical lithospheric fragment of debated origin. The PVF is the only basaltic field regionally, has been studied geochemically in the past, and is also known for the presence of abundant mantle xenoliths. Here, we describe new geochemical data on rocks recently dated by Ar-Ar chronometry and show that while we can reproduce virtually all previous results, there is a clear temporal evolution of the magmatic system. There is an increase of over 80°C in temperatures determined by the Si activity thermometer, from 1,300°C to 1,380°C during the~0.5-Myr duration of volcanic activity, which is accompanied by several coherent trends in geochemistry, among which the decrease of Zn/Fe and 87 Sr/ 86 Sr ratios over time. Earlier, higher Zn/Fe ratios are indicative of a pyroxenite/eclogite-dominated source, which gradually changed to a peridotite-dominated source. These characteristics are typical of a dynamic mantle in which vertical mantle lithosphere tectonics, either due to slab rollback or mantle dripping plays a role and are not consistent with simple decompression melting of asthenosphere. Synchronous adakitic rocks found about 25-30 km east of PVF are presumed to be slab melts and are consistent with the Vrancea slab rollback as the trigger for mantle melting responsible for the PVF.

We performed a detrital zircon (DZ) U‐Pb geochronologic survey of the lower parts of the Danube River approaching its Danube delta, Black Sea sink, and a few large tributaries (Tisza, Jiu, Olt, and Siret) originating in the nearby Carpathian Mountains. Samples are modern sediments. DZ age spectra reflect the geology and specifically the crustal age formation of the source area, which in this case is primarily the Romanian Carpathians and their foreland with contributions from the Balkan Mountains to the south of Danube and the East European Craton. The zircon cargo of these rivers suggests a source area that formed during the latest Proterozoic and mostly into the Cambrian and Ordovician as island arcs and back‐arc basins in a Peri‐Gondwanan subduction setting (~600–440 Ma). The Inner Carpathian units are dominated by a U‐Pb DZ peak in the Ordovician (460–470 Ma) and little inheritance from the nearby continental masses, whereas the Outer Carpathian units and the foreland have two main peaks, one Ediacaran (570–610 Ma) and one in the earliest Permian (290–300 Ma), corresponding to granitic rocks known regionally. A prominent igneous Variscan peak (320–350 Ma) in the Danube's and tributaries DZ zircon record is difficult to explain and points out to either an extra Carpathian source or major unknown gaps in our understanding of Carpathian geology. Younger peaks corresponding to arc magmatism during the Alpine period make up as much as about 10% of the DZ archive, consistent with the magnitude and surface exposure of Mesozoic and Cenozoic arcs.