Geochemistry of amphibolites and related graphitic gneisses from the Suchý and Malá Magura Mountains (central Western Carpathians) – evidence for relics of the Variscan ophiolite complex

Abstract

Three small bodies of amphibolites and associated graphitic gneisses from the Suchý and Malá Magura Mountains (Tatric Megaunit, central Western Carpathians) have been studied by petrographic and geochemical methods. Isolated, fault-bounded bodies first hundreds of meters in size are located in the complex of the Early Paleozoic paragneisses and migmatites intruded by the Lower Carboniferous granitoid rocks. Amphibolites (locally actinolite schists) were formed from effusive basalts, dolerites or isotropic gabbros hydrothermally altered and veined before the regional metamorphic transformation. Distribution of the trace elements relatively immobile during the metamorphic alteration (HFSE, REE, Cr, V, Sc) is similar to E-MORB type in the Malá Magura Mountain or to N-MORB/E-MORB types in the Suchý Mountain. Graphitic gneisses to metacherts are rich in silica (up to 88 wt. %) and C tot , poor in other major element contents and display negative Ce-anomaly, enrichment in HREE, V, Cr and U. They were probably originally deposited as non-carbonate and silica-rich deep-sea sediments in anoxic conditions. The oceanic provenance of amphibolites and related graphitic gneisses clearly indicates their oceanic crust affinity and identity with the uppermost part of the ophiolite sequence. Ophiolite bodies from the Suchý and Malá Magura Mountains are supposed to be relic fault blocks identical with the Upper Devonian Pernek Group which represents a Variscan ophiolite nappe preserved to large extent in the Malé Karpaty Mountains located in the Tatric Megaunit further to the southwest. All these ophiolite relics are vestiges of the original ophiolite suture created by oceanic closure in the Lower Carboniferous.

Archaeometrical results related to Neolithic amphibolite stone implements from Northeast Hungary

“…The bulk chemistries of Gemericum, Veporicum and Tatricum amphibolites are very similar to each other and also to that of our samples, having subalkaline, tholeiitic character (Fig. 3) (Bajanik & Hovorka, 1981, Hovorka et al, 1993, Ivan et al, 2001, Faryad et al, 2005, Ivan & Méres, 2015. On the AFM diagram, the distribution of the data of the samples and the data of the possible provenance fields overlap each other (Fig.…”

“…On the AFM diagram, the distribution of the data of the samples and the data of the possible provenance fields overlap each other (Fig. 4) (Bajanik & Hovorka, 1981, Hovorka et al, 1993, Ivan et al, 2001, Faryad et al, 2005, Ivan & Méres, 2015. Using only the major element composition of bulk chemistry, the provenance field cannot be specified.…”

The birth of the Alps: Ediacaran to Paleozoic accretionary processes and crustal growth along the northern Gondwana margin

“…In the Carnic Alps, the arguably subducted basin may be recorded by shelf sequences only with scarce intraplate alkaline basalts (i.e., Raabtal; Läufer et al 2001 and references therein). Even when present in adjacent regions such as the Western Carpathians, ophiolites only comprise minor bodies with a geochemical fingerprint that suggests an association with a continental margin (Ivan and Méres 2015), thus implying a relatively minor oceanic basin. Neither the Rheic nor the Paleotethys oceanic crust might have thus developed in the back-arc of the Alpine basement and adjacent tectonostratigraphic domains, at least not in the context of a large basin.…”

Rhenium-osmium geochronology of gersdorffite and skutterudite-pararammelsbergite links nickel–cobalt mineralization to the opening of the incipient Meliata Ocean (Western Carpathians, Slovakia)

“…The Tatric and Veporic Superunits comprise large Devonian to Late Carboniferous syn-to post-collisional I-and S-type granitoids, Variscan felsic orthogneisses, paragneisses, migmatites, calc-silicate rocks, scarce metamorphosed black shales, and remnants of retrogressed meta-ultramafic rocks (Broska and Kubiš 2018;Kohút and Larionov 2021;Janák et al 2020). Some Tatric complexes contain larger bodies of metamorphosed basalts, dolerites, gabbros, and sediments with variable amount of meta-organic matter and pyrite (Ivan and Méres 2015). These rocks are considered to represent metamorphosed and tectonically dismembered ophiolite sequences.…”