Timing of rifting in the Central Western Carpathians post-Variscan
orogeny and provenance of the Meliata Ocean
Abstract
Slovakia is located within the Central Western Carpathians (CWC), one of
many connected curved mountain belts prominent throughout the
Mediterranean area and Europe. It is divided into tectonic domains
considered “superunits,” termed the Gemeric, Veporic, and Tatric that
correlate to the lower, middle, and upper Austoalpine nappes. For
example, granite bodies exposed in the unit (termed apophyses) yield a
wide range of zircon ages from 310±21 Ma to 87±4 Ma. This range of ages
leads to problems in deciphering where the Gemeric unit was located in
global plate reconstructions of eastern Europe and the western
Carpathians specifically. This case study involves U-Pb dating of
magmatic and detrital zircons from the Gemeric tectonic unit. This area
records the Variscan orogeny that formed the CWC, rifting, and opening
of the Meliata Ocean. This ocean was created due to the formation of a
back-arc basin during closing/subduction of the Paleo-Tethys Ocean. We
aim to constrain the timing of rifting and identify the provenance of
Meliata Ocean radiolarian sediments collected from an obducted Meliata
ophiolite suite (Dobsina, Slovakia). The relative age of the Variscan
orogeny extends from the late Devonian to early Permian and was followed
by rifting throughout the Mesozoic within the CWC. Eventually, the
Meliata Ocean closed during the Cretaceous. Zircons from several S-type
granites were collected throughout the Gemeric tectonic unit; they were
dated using Laser Ablation Inductively Coupled Plasma Mass Spectrometry
and imaged using cathodoluminescence. Rim crystallization ages from the
granites are 295.8±3.4 Ma (2σ, 238U-206Pb) to 213.1±4.4 Ma. Ages from
the detrital zircons are 346.4±4.5 Ma to 263.9±2.7 Ma, indicating that
sediments overlying the Meliata Ocean ophiolite contain remnants of both
the Variscan orogeny and Gemeric granites.