Origin and evolution of the South Carpathians basement (Romania): a zircon and monazite geochronologic study of its Alpine sedimentary cover

Evolution of the Sibişel Shear Zone (South Carpathians): A study of its type locality near Răşinari (Romania) and tectonic implications

“…Instead, it is a two mica gneissic rock whose augen plagioclase crystals give the false impression of an orthogneiss. The distribution of concordant U‐Pb ages (Figure a) is a feature typical of many of the Lotru Metamorphic Suite rocks and Alpine sedimentary rocks derived from them [ Balintoni et al ., ; Stoica et al ., ]. Overall the zircon age distribution in this rock shows a peak in the mid‐Ordovician; the presence of a number of zircon with latest Proterozoic ages is typical of many rocks previously analyzed from the Lotru Metamorphic Suite (see review paper by Balintoni et al .…”

“…The Lotru Metamorphic Suite is the largest metamorphic unit in the South Carpathians and has a rather complex lithology and tectonic evolution. It is dominated by latest Precambrian to Early Silurian zircon ages with a single large mid‐Ordovician age peak at 460–470 Ma, likely reflecting a subduction‐related flare‐up event which probably makes up more that 70% of the exposed basement [ Balintoni et al ., ; Stoica et al ., ]. That age peak is in fact a global zircon magmatic arc flare‐up event, perhaps the largest in the Phanerozoic [ Ducea et al ., ] and is certainly reflected in many basement terranes of the Alpine‐Carpathian domain [ von Raumer et al ., ].…”

“…A younger unconformable sedimentary sequence (now garnet micaschists) overlays the arc sequence. They were metamorphosed during a Variscan Barrovian collisional event documented by Sm‐Nd garnet [ Medaris et al ., ] and U‐Th/Pb monazite [ Stoica et al ., ] ages. The consistent presence of the inherited age peaks is taken to indicate the proximity of a continental mass.…”

“…The Lotru Metamorphic Suite includes Ordovician to Silurian island arc lithologies mixed with two mica schist representing cover units of the arc all of whom were unconformably covered by a metasedimentary unit of staurolite and garnet micaschists (locally known as the Negovanu schists) (M. N. Ducea et al, unpublished data, 2016). More than 70% of the zircons recovered from various Lotru Metamorphic Suite lithologies are 460–470 Ma old, an age concentration that is reflected also in detrital Cretaceous and younger sedimentary units from nearby basins [ Stoica et al ., ]. A second main population of zircons from the Lotru Metamorphic Suite yielded ages around the Precambrian‐Cambrian boundary (570–550 Ma).…”

Lower Cretaceous Provenance and Sedimentary Deposition in the Eastern Carpathians: Inferences for the Evolution of the Subducted Oceanic Domain and its European Passive Continental Margin

“…The details regarding pre-Mesosoic island arc formation and assembly remain poorly resolved petrologically and structurally, but sufficient zircon chronology data are available (Balintoni et al, 2010b(Balintoni et al, , 2014Balintoni & Balica, 2013;Ducea et al, 2016, for a review) to fingerprint potential derivation from the Dacia mega-unit using zircon Kernel Density Estimate plots (Ducea et al, 2018) of sedimentary rocks deposited in the former Ceahlău-Severin oceanic basin. A major Ordovician peak at 458 -472 Ma represents the culmination of a high-flux magmatic event (Stoica et al, 2016) that is distinctive for the Dacia mega-unit. Other significant zircon peaks are found at 520, 540, 580, and 600 Ma trailing toward slightly older ages (Figures 3a and 3b) but not beyond 750 Ma (Ducea et al, 2018).…”