67 GeoLines 20 2006 Do We Have a Remnant of the Hanseatic Terrane and/or Rheno- Hercynian Ocean in the Western Carpathians? – A Case Study from the Devonian of the Považský Inovec Mts. Milan KOHÚT Dionýz Štúr Institute of Geology, 817 04 Bratislava, Mlynská dolina 1, Slovak Republic Geodynamic evolution understanding in orogenic belts like the Alps, Carpathians or Himalayas that contain multistage metamor- phic and magmatic episodes is often problematic. The polyoro- genetic history of such orogenic belts, marked by incorporation of pre-Mesozoic polycrystalline basement blocks into young Alpine structures, resulted in formation of complicate rocks puzzle often characterised by juxtaposition of various terranes and/or blocks due to multistage tectonic evolution by large-scale nappe and strike-slip tectonics. However, unravelling orogenic episodes in the modern polyorogenetic belts is practically impossible with- out precise stratiication and dating, as lithological and structu- ral relations within various fragments are frequently ambiguous. The European Hercynian (Variscan) and Alpine mountain chains are typical collisional orogens, and are built up of pre-Hercy- nian basement blocks that, in most cases, originated at the north Gondwana margin. Such pre-Hercynian elements were part of a pre-Ordovician continental ribbon – the Hun superterrane in the former eastern prolongation of Avalonia, and their present-day distribution resulted from juxtaposition through Hercynian and/ or Alpine tectonic evolution (Stampli and Borel 2002, von Rau- mer et al. 2003). The Devonian was a period of relative silence in the Earth history between vanishing Caledonian movement in the Lower Devonian and beginning of Hercynian (Variscan) oroge- nesis in the Upper Devonian. Thick terrigeneous accumulations of so-called Old red sandstone, huge marine carbonatic and fly- sch sediments, as well as extensive products of submarine basic and/or bimodal volcanism represent the rocks record of this pe- riod. Sedimentary record has in European realm general feature of changing facies from terrigeneous clastic material at the north (Old red continent evolution) through a mixture of psammitic-pe- litic depositions and/or neritic-pelagic interchange (Rheno-Hercy- nian evolution) to calcareous sedimentation with pelitic intercala- tion (Bohemian – Barrandian’s evolution) at the southern margin. Devonian in the Western Carpathians (WC) has not large area extension in general. There are known only the Gelnica and Rako- vec Groups in the Gemeric unit that consist of metagreywackes, phyllites, lydites, carbonates and basic volcanics, the Harmonia Group in the Malé Karpaty Mts. (Tatric unit) with similar metamor- phosed rocks (phyllites, greywackes, limestones and basic volcan- ics), and the Predná hola sedimentary-volcanogenic complex (Vepo- ric Unit). Devonian limestones were sporadically described from deep boreholes at the southern Slovakia. Recently in the frame of construction new geological map of the Považský Inovec Mts., there was documented an unusual volcano-sedimentary complex for the Tatric unit of the WC. This complex was displayed in the oficial General map of Slovakian territory as amphibolites (Kame- nický 1956, Kamenický in Buday et al. 1962). However, our ield and petrological study proved that the dominant part of this com- plex consists of dark grey ine-grained laminar to weakly banded pe- litic-psammitic metamorphosed rocks – metagreywackes and phyl- lites. There were identiied locally sills of submarine basic volca- nics – amphibolites and/or its pyroclastic analogues, layers of black schists respectively graphitic metaquartzites and lydites, as well as calk-silicate hornfels – erlans and whole complex was called as Hlavinka volcano-sedimentary metamorphic complex (Kohút et al. 2005). The most common rocks of this complex – metagreywackes and phyllites are composed by quartz, plagioclase, K-feldspar, bio- tite and organic matter (graphite), in accessory content are present garnet, zircon and monazite. Metamorphic overprint of original volcano-sedimentary sequence reach to upper part of greenschist facies respectively lower part of amphibolite facies with T = 500 to 550 °C and P = 300–350 MPa (Kohút and Siman 2005). Due to apparent dominance of amphibolites there was omitted stratigraphic determination indicated Devonian age of palynomorphs, tracheids and phyto detritus (Čorná and Kamenický 1976) separated from black schists, and this part of the Tatric crystalline was regarded as “deep Lower Paleozoic basement” till present. However, cru- cial for the Devonian classiication was recent discovery of hema- tite metaquartzites – a typical analogue of the Lahn-Dill volcano-se- dimentary iron ores (Kohút and Havrila 2006) within the Hlavin- ka Group. Geochemistry conirmed greywacke protolith character of prominent metamorphic rocks (metagreywackes and phyllites) from the Hlavinka Group, whereas these rocks were sedimented at continental slope in the back-arc basin. These greywacke were deri- vate from an acid and/or intermediate magmatic rocks source that originated in an active continental arc. Rather unusual MORB geo- chemical character of metabasic rocks – amphibolites was shown as standard for Rheno-Hercynian evolution of the Devonian (Floyd 1995). Relative lack of modern stratigraphic data from Hlavinka Group partially supply dating of uraninite and monazite with the electron microprobe (CAMECA SX-100) in an attempt to broadly constrain formation ages of greywackes and hematite metaquartzi- tes. The uraninite origin (390–380 Ma) was the most probably syn- chronous to formation of submarine-exhalation iron ores, whereas monazite data (350–330 Ma) from identical samples indicate rath- er inal Meso-Hercynian metamorphic overprint of volcano-sedi- mentary pile (Kohút et al. in preparation). The Carpathians form part of an extensive, equatorial, oroge- nic belt extending from Morocco in the Atlas Mountains, through the Alps, Dinarides, Pontides, Zagros, Hindukush to the Himalayas and to China. The Western Carpathians are the northernmost, E–W trending branch of this Alpine belt, linked to the Eastern Alps in the west and to the Eastern Carpathians in the east. Nowadays veriica- tion of Devonian in the Považský Inovec Mts., call for some geo-