Geochemistry and Sr, Nd isotopic composition of the Hronic Upper Paleozoic basic rocks (Western Carpathians, Slovakia)

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Several magmatic events based on U-Pb zircon geochronology were recognized in the Permian sedimentary succession of the Northern Gemeric Unit (NGU). The Kungurian magmatic event is dominant. The later magmatism stage was documented at the Permian-Triassic boundary. The detrital zircon assemblages from surrounding sediments documented the Sakmarian magmatic age. The post-orogenic extensional/transtensional faulting controlled the magma ascent and its emplacement. The magmatic products are represented by the calc-alkaline volcanic rocks, ranging from basaltic metaandesite to metarhyolite, associated with subordinate metabasalt. The whole group of the studied NGU Permian metavolcanics has values for the Nb/La ratio at (0.44-0.27) and for the Nb/U ratio at (9.55-4.18), which suggests that they represent mainly crustal melts. Magma derivation from continental crust or underplated crust is also indicated by high values of Y/Nb ratios, ranging from 1.63 to 4.01. The new 206 U-238 Pb zircon ages (concordia age at 269 ± 7 Ma) confirm the dominant Kungurian volcanic event in the NGU Permian sedimentary basin. Simultaneously, the Permian-Triassic boundary volcanism at 251 ± 4 Ma has been found for the first time. The NGU Permian volcanic activity was related to a polyphase extensional tectonic regime. Based on the new and previous U-Pb zircon ages, the bulk of the NGU Permian magmatic activity occurred during the Sakmarian and Kungurian. It was linked to the post-orogenic transpression/transtension tectonic movements that reflected the consolidation of the Variscan orogenic belt. The Permian-Triassic boundary magmatism was accompanied by extension, connected with the beginning of the Alpine Wilson cycle.

Section: Geological Settingmentioning

confidence: 99%

First evidence for Permian-Triassic boundary volcanism in the Northern Gemericum: geochemistry and U-Pb zircon geochronology

Vozárová¹,

Presnyakov²,

Šarinová³

et al. 2015

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“…Centroid age is the age corresponding to the crossing of functions y = f(x) and x = f(y), where x = U / Pb and y = Th / Pb. (andesite-basalts of the 2 nd eruption phase; Vozár 1997;Dostal et al 2003;Vozár et al 2015) dated after the Illawara Reversal Magnetic Horizon (Vozárová & Túnyi 2003), as well as from the Bôrka Nappe (Vozárová et al 2012) and Silicicum (Demko & Hraško 2013).…”

Section: Discussionmentioning

confidence: 99%

Late Permian volcanic dykes in the crystalline basement of the Považský Inovec Mts. (Western Carpathians): U–Th–Pb zircon SHRIMP and monazite chemical dating

Pelech¹,

Vozárová²,

Uher³

et al. 2017

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This paper presents geochronological data for the volcanic dykes located in the northern Považský Inovec Mts. The dykes are up to 5 m thick and tens to hundreds of metres long. They comprise variously inclined and oriented lenses, composed of strongly altered grey-green alkali basalts. Their age was variously interpreted and discussed in the past. Dykes were emplaced into the Tatricum metamorphic rocks, mostly consisting of mica schists and gneisses of the Variscan (early Carboniferous) age. Two different methods, zircon SHRIMP and monazite chemical dating, were applied to determine the age of these dykes. U-Pb SHRIMP dating of magmatic zircons yielded the concordia age of 260.2 ± 1.4 Ma. The Th-U-Pb monazite dating of the same dyke gave the CHIME age of 259 ± 3Ma. Both ages confirm the magmatic crystallization at the boundary of the latest Middle Permian to the Late Permian. Dyke emplacement was coeval with development of the Late Paleozoic sedimentary basin known in the northern Považský Inovec Mts. and could be correlated with other pre-Mesozoic Tethyan regions especially in the Southern Alps.

“…The NGU zone contains relics of the Variscan collision suture, characterized by thrust wedges of the two pre-Carboniferous terranes, the medium/high-grade gneiss-amphibolite Klátov Complex and the low-grade Rakovec Complex, and relics of the Mississippian syn-orogenic deep-water turbidite sequence. Pennsylvanian shallow-marine to paralic and Permian continental sedimentary basins postpone the main collisional events (e.g., Bajaník et al 1983;Spišiak et al 1985;Vozárová & Vozár 1988;Hovorka et al 1988;Németh 2002;Németh et al 2004;Ivan 2009;Radvanec et al 2017). Defor mational and metamorphic events recorded in both pre-Carboniferous terranes occurred in the Late Devonian-Mississippian, which is documented by their reworked rock fragments within the overstepping Pennsylvanian conglomerates (Krist 1954;Vozárová 1973Vozárová , 2001) and by several geochronological data (Vozárová et al 2005(Vozárová et al , 2013Putiš et al 2008Putiš et al , 2009a.…”

Section: Geological Setting Of the Ngu Carboniferous-permian Sedimentmentioning

confidence: 99%

Exhumation history of the Variscan suture: Constrains on the detrital zircon geochronology from Carboniferous–Permian sandstones (Northern Gemericum; Western Carpathians)

Vozárová

Šarinová

Laurinc

et al. 2019

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The Late Paleozoic sedimentary basins in the Northern Gemericum evolved gradually in time and space within the collisional tectonic regime of the Western Carpathian Variscan orogenic belt. The detrital zircon age spectra, obtained from the Mississippian, Pennsylvanian and Permian metasediments, have distinctive age distribution patterns that reflect the tectonic setting of the host sediments. An expressive unimodal zircon distribution, with an age peak at 352 Ma, is shown by the basal Mississippian metasediments. These represent a relic of the convergent trench-slope sedimentary basin fill. In comparison, the Pennsylvanian detrital zircon populations display distinct multimodal distributions, with the main age peaks at 351, 450, 565 Ma and smaller peaks at ~2.0 and ~2.7 Ga. This is consistent with derivation of clastic detritus from the collisional suture into the foreland basin. Similarly, the Permian sedimentary formations exhibit the multimodal distribution of zircon ages, with main peaks at 300, 355 and 475 Ma. The main difference, in comparison with the Pennsylvanian detrital zircon assemblages, is the sporadic occurrence of the Kasimovian– Asselian (306–294 Ma), as well as the Artinskian–Kungurian (280–276 Ma) igneous zircons. The youngest magmatic zircon ages nearly correspond to the syn-sedimentary volcanic activity with the depositional age of the Permian host sediments and clearly indicate the extensional, rift-related setting.