Cretaceous hydrothermal remobilization in the Central Western Carpathians: Dating of monazite-(Ce), xenotime-(Y), and hematite

In this work, we investigated two regionally distributed and economically unimportant mineralizations.The first -quartz-hematite mineralization is found as veinlets and fracture filling, both in Variscan basement rocks and in Lower Triassic sandstones in the Tatric Unit.Using (U-Th)/He analysis, one hematite sample from Magurka-Kapustisko was dated to 97.5 4.4 Ma; another sample gave a lower precision age of 71 40 Ma.Previous geological and fluid-inclusion evidence suggests that the formation of the hematite veinlets could be linked to fluids expelled from the soles of moving thick-or thin-skinned nappes.The second studied mineralization consists of quartz with chlorite, tourmaline and REE phosphates monazite-(Ce) or xenotime-(Y), embedded in older mineralizations (siderite-ankerite veins -ierny Balog, Jedov Kostoany, or metamorphosed hematite-magnetite ores -Bacch).Our sample set was augmented by one metamorphic rock with REE phosphates (site Mur; all samples from Veporic Unit).The U-Pb (LA-ICP-MS) ages from Jedov Kostoany, ierny Balog and Mur fall into a narrow range of 81-86 Ma, with one outlier at 77 Ma.The ages from Bacch are somewhat older, between 87 and 92 Ma.The older ages from the nothernmost part of the Veporic unit reflect the progressive exhumation of this unit from north to south.At Jedov Kostoany, the ages of REE phosphates are only slightly older than those previously determined on hydrothermal muscovite, thus documenting lasting hydrothermal activity at these times.Large xenotime-(Y) crystals from uma (Gemeric Unit), associated with apatite, gave a spread of ages, with the main peak centered at 143 2 Ma.This age likely corresponds to Early Cretaceous compression, folding, and thrusting in the Gemeric Unit.An older event, located in our data at 183 3 Ma, corresponds to pre-existing, partially remobilized mineralization, recorded also in previously published ages related to uraninite.Remobilization was probably caused by unroofing of the Variscan basement of the Gemeric Unit and growth of the Meliata ocean basin.