The Šobov High-Sulfidation System
The Šobov high-sulfidation epithermal deposit is 2 km north of Banská Štiavnica, and formed from the oldest hydrothermal system of the Štiavnica stratovolcano. Its metasomatic quartzite core is quarried from an open pit as the raw material for production of refractory bricks in a nearby factory. Exploration by drilling and underground galleries proved reserves of 6.2 million tons of 96 — 97 % SiO2, 1–1,5% Fe2O3, 0.2 – 0.3 % A12O3 and 0.7–1.1% TiO2 (Polák, 1960). At present the industrial reserves of the deposit are 5.3 million tons at 97.8 % SiO2, 0.6% Fe2O3 and 0.84% Al2O3 + TiO2 (Balances of reserves at exclusive mineral deposits of Slovakia, 1996). Local accumulations of agalmatolite (nowadays pyrophyllite) and dillnite (nowadays zunyite) in karstic cavities of adjacent carbonate rocks on the northern side of the deposit were exploited during the 19th century. Exploitation of the deposit since the early 1960s has eventually created environmental problems owing to dumping of pyrite-rich argillic-altered rock on large heaps and subsequent weathering. The immediate risk has been reduced by a drainage system, which takes acid waters to abandoned mines, where they are diluted by ground waters.
The quartzite of the deposit has been for a long time a matter of disputes, being variably interpreted as sedimentary Triassic quartzite affected by recrystallization (e.g., Lipoid, 1867; Szabó, 1891), or hydrothermal metasomatic quartzite (e.g., Böckh, 1901). The hydrothermal origin was accepted also by Polák (1960), who conducted detailed exploration by drilling and galleries to calculate the reserves for future exploitation.
Figures & Tables
Epithermal Mineralization of the Western Carpathians
km 0 The first Shell gas station on the M3 motorway after the end of Budapest sign. From here, the M3 motorway crosses the Gödöllő Hills during the next 35–40 kilometers. This area consists of a 2 km thick Tertiary-Quaternary sedimentary sequence underlain by Mesosoic carbonate rocks. On the present surface, loess from the Pleistocene glaciation and drift sand deposits are the most common sediments.
60 On the left side ahead the first view of the Western Mátra Mtns. appears. They are the highest mountains of Hungary with 1014 m elevation at the Kékes summit. The visible part of the Western Mátra Mts. is composed of Miocene andesitic-rhyolitic rocks forming a caldera structure with approximately 15 km diameter. The Mátra Mtns. is the object of the field programme on the fourth day and details of regional geology can be found in the guidebook. In front of the mountains the town of Gyöngyős can also be seen.
69 The M3 motorway crosses one of the traditional wine-producing area of Hungary. The vineyards covering 28 000 acres on the southern foreland of the Mátra Mts. are famous for various white vines. The center of the wine region is Gyöngyős.
Behind the vineyards to the left (north) the Eastern Mátra Mtns. can be seen. This part of the Matra Mtns. is built up by andesitic rocks of Miocene age. In contrast to the Western Matra Mts., large caldera structures cannot be found here and the area is very poor in hydrothermal mineralisation.
The boundary between the flat southern foreland and the mountains roughly corresponds to the shoreline of an Upper Miocene (Pannonian) brackish sea. Important lignite deposits with 3.5 billion� tons resource were formed in this paleo-coastal region. The exploitation of lignite started before World WarII in this area.
From here to Miskolc, the motorway follows the boundary between the Alföld (The Great Plain) and hilly areas composed of Miocene volcanic units such as the Mátra Mtns. as well as the Bükkalja Hills. The Alfold to the south is the major agricultural area of Hungary and geologically corresponds to the Pannonian Basin. The subsidence of the basement that is composed of various metamorphic, granitic and Mesosoic-Tertiary sedimentary terrains started during the Miocene. Due to the rapid subsidence the basement now is at more than 4000 m depth in the southern part of the Alföld. The fast subsidence is related to a back-arc