Sedimentary Manganese Deposits of Hungary

Cseh, Németh József and Konda, József and Grasselly, Gyula and Szabó, Zoltán (1980) Sedimentary Manganese Deposits of Hungary. In: Geology and Geochemistry of Manganese. Akadémia Kiadó, Budapest, pp. 199-221. ISBN 9630516675

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Abstract

In the Bakony Mountains (Hungarian Central Mts) the Jurassic sedimentary sequence contains Mn-indications from the Middle Liassic up to the Upper Jurassic members, and in two areas (Úrkút and Eplény) of the SE margin of the Jurassic range manganese ore deposits are found in the Lower to Upper Liassic. The geosyncline of Úrkút had been much larger than that of Eplény and thus, the deposit of Úrkút is more valuable from the industrial point of view. In the area of occurrences mentioned the carbonate sedimentation ceased in the Middle — Upper Liassic (Toarcian) boundary and it is replaced by a pelitic sedimentation characterized by manganese-producing periods. The bedded manganese deposits of the Bakony Mountains are primarily constituted of carbonate and oxide ores, subsequently oxidized and redeposited by secondary process. From the point of view of the geological history of the manganese beds, the New Kimmerian movements were of considerable significance because greater regions got to the surface and were oxidized and redeposited and large areas were eroded as well. The Upper Liassic manganese sequence of Úrkút area in its primary development is characterized by alternating layers of two rock types, i.e. of dark grey radiolarian clay marl and fine-layered manganese carbonate ore, with a thickness of 35 to 40 metres in average. The carbonate protore was oxidized and the autochthonous oxidized manganese ores are mostly cryptomelane, pyrolusite, manganite, psilomelane. In the eastern part of the Úrkút area iron-manganese ores are found. In Eplény area manganese is deposited primarily in form of oxides and oxyhydrates onto the uneven surface of the Lower — Middle Liassic, with a thickness of 2 to 5 metres. The manganese oxide bed is overlain by radiolarian clay marl with thin manganese carbonate interbeddings. The manganese deposits of the Bakony Mountains are of marine-sedimentary origin and can be assigned to the manganese formations which can be traced in the Alpine Jurassic, e.g. Graubünden (Switzerland), Mikusovce (Czechoslovakia), Kammerlingalm (Austria), and Chocholowska (Poland). In the foreground of the Bükk Mountains considerable sedimentation took place since the Eocene; the Oligocene is of 300 to 1000 metres in thickness. In the Rupelian of the sequence interbedded manganese carbonate deposits of 0.1 to 0.5 metres in thickness are found. The beds were oxidized near the surface. The formation is similar to the Oligocene sedimentary manganese ores being widespread in the Mediterranean region. The Hungarian Oligocene manganese beds are with no industrial significance. In the Uppony Mountains, in the Lower Carboniferous shale sequence several Mn- and Fe-bearing intercalations and lenses are known with 8— 15% Mn and 11—15% Fe content, which were mined in the 18th century. The occurrence is without industrial significance.

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