Fehér Béla (szerk.): Az ásványok vonzásában, Tanulmányok a 60 éves Szakáll Sándor tiszteletére (Miskolc, 2014)
Kozák Miklós - Rózsa Péter - McIntosh Richard William - Papp István - Mocsár-Vámos Mariann - Plásztán József: A miskolci Avas-domb őskori kőipara és földtani környezete
Fehér B. (szerk.) (2014): Az ásványok vonzásában. Tanulmányok a 60 éves Szakáll Sándor tiszteletére. Herman Ottó Múzeum és Magyar Minerofil Társaság, Miskolc, pp. 135-145. A miskolci Avas-domb őskori kőipara és földtani környezete Prehistoric stone industry in the Avas Hill, Miskolc and its geological conditions KOZÁK Miklós*, RÓZSA Péter, McINTOSH Richard William, PAPP István, MOCSÁR-VÁMOS Mariann & PLÁSZTÁN József Debreceni Egyetem, Ásvány- és Földtani Tanszék, 4032 Debrecen, Egyetem tér 1. * E-mail: kozak.miklos@science.unideb.hu Abstract The paper summarizes the most important geological and archaeological publications regarding the Avas Hill in Miskolc, NE Hungary over the last 100 years. It focuses on the position, material and significance of the layers in the upper part of the series the material of which was mined and used for making stone tools. Due to the lack of boreholes with appropriate depth earlier publications on the Avas Hill are incomplete. They are frequently based on only one-or-two nice outcrops and mosaic information and the position, extension, facies and material of the outcrops are assessed inappropriately frequently. The most recent studies in 2012 based on deep boreholes and various analyses proved the Sarmatian age of the entire Avas Hill above the level of the Szinva creek and that it is composed of formations deposited in shallow marine environments. Boreholes, outcrops and geological profiles in cellars expose the series in three dimensions. Based on these it can be proved that although the andesitic volcanic products are present in the entire series in some form they form no continuous masses apart from the 5-25 m thick andesite tuff layer separating the lower and upper Sarmatian and no lava bodies were found either despite the fact that such bodies are known in other parts of the Tardona Hills, just north of the Avas. The andesitic volcanism was supplied from local centres in the Avas just like in elsewhere characterised by frequent explosions due partly to the wet sediment strata and water cover and partly to the repeated occurrences of tufogene clay and argillaceous tuff layers similarly to other parts of the region and to their tightening effect (e.g., foreground of Tardona, surroundings of the Egyház valley, Galambos, Szoros valley, Özvény valley). Due to this tightening the magma ascended at several points above the basement fractures, however, it lost much energy via explosions and had small supply. Where its small intrusions “solidified” in the sediment series or where it formed small lava breccias and peperites reaching the surface shallow marine abrasion washed its material forming lens like andesite sands occasionally with gravel cords. Andesite gravel accumulations indicate nearshore environment and fluvial sediment supply. The whole Sarmatian is characterised by a periodical acid tuff explosion supplied from distant centres creating a few dm or m thick tuff cover. This tuff was bentonitized during deposition and where its material was reworked intrabasinally the concentration of montmorillonite was increased significantly (50-90%). Around 8-10 such argillized rhyolite tuff, bentonite and bentonite like clayey layers are found in the sediment series of the Avas interbedded with yellow, loose sandstone and grey andesite sand lenses. The series of the Avas is characterised by a local multi-phased andesite volcanism in shallow marine environment influenced by nearshore currents and variable shore effects and a repeated deposition of rhyolite tuff transported aerially from distance centres. In the closing stages of the upper Sarmatian tectonic uplift and temporary shallowing characterize the area with the simultaneous bursting of thermal springs from the subvolcanic surroundings heated by magma intrusions along NE-SW striking structural tinctures. These result in the formation of limnoquartzite beds with limited extension repeated twice of three times in a 7—10 m thick strata group within the series. Calcareous precipitates are found in between them either mixing to the silica material or forming separate horizons similarly to the features visible in the waters of the Yellowstone National Park in greater volume today (Buday & Krassay, 2007). The material of the limnic opalites and limnic chalcedony was proved to be ideal raw-material for man in ancient times to make stone tools from them. Therefore one of the oldest and greatest quartzite processing sites in the Carpathian Basin was formed in the Avas Hill and in this way the area can be regarded as inhabited continuously for 70,000 years.
