Genesis of Manganese Oxide Ores in the Úrkút Basin

Szabó, Zoltán and Grasselly, Gyula (1980) Genesis of Manganese Oxide Ores in the Úrkút Basin. In: Geology and Geochemistry of Manganese. Akadémia Kiadó, Budapest, pp. 223-236. ISBN 9630516675

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Abstract

Manganese in the sedimentary basin of Úrkút originally accumulated as carbonate during the Upper Liassic. The development of the carbonate sequence is complete in the central part of the basin development while it is partial at the margin. In the complete sequence all the carbonate ore types observed in this area can be found. Toward the margins the more deeply lying types gradually disappear. The carbonate ores have been oxidized, eroded and redeposited in a large area. The autochthonous oxide ore formed in situ retained the characteristic structure of the original carbonate. In the oxidation processes it is probably the pyrite content of the radiolarian clay marl overlying the bed that played an important role. Within the bed, manganese and iron were mobilized by the acidic solution produced by the oxidation of the pyrite, promoting the separation of manganese from the clay minerals. The role of acidic solution is also shown by the chemical investigation of solutions seeping through the oxide beds. The SO, content of the solutions is the highest in the transitional zone between the carbonate and oxide ores and its amount gradually decreases toward the redeposited and eroded areas. In the autochthonous beds the amount of manganese and iron increases during the oxidation while the amount of the silica and phosphorous decreases in the oxidized zone. The differences among the carbonate and oxide beds as well as the redeposited ores are well shown by the frequency distribution curves of Mn, Fe, S i0 2 and P. On the basis of about 5000 analyses a diagram was constructed showing the rate of enrichment of the manganese content during the oxidation in the beds.

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