Naslov
Sedimentary low-manganese hematite deposits of the Bukovica area in the Northwestern Mt. Petrova gora, Central Croatia.
(Sedimentary low-manganese hematite deposits of the Bukovica area in the northwestern Mt. Petrova gora, Central Croatia.)

Autori
Čop, Milivoj ; Jurković, Ivan ; Slovenec, Dragutin.

Izvornik
Rudarsko-geološko-naftni zbornik (0353-4529) 10 (1998); 1-24

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Middle-Permian low-manganese hematite deposits; Geotectonic setting; XRD; AAS; DTA analyses; Morphology; Paragenesis; Genesis; Bukovica; Croatia

Sažetak
Middle-Permian Gröden deposits crop out on the surface of 0.8 km2 in the Bukovica area and on the surface of 0.8 km2 in the Mt. Loskunjska gora in the NW part of the Petrova gora Mountain. One half of the Bukovica Gröden deposits contains in its lowest parts 1 to 5 m (in average 2.5 m) thick hematite bed cutted in blocks by NE-SW stretching vertical, normal and reverse faults. The hematite bed is unconformably underlain by Lower Permian quartz-wackes (subgraywackes) intercalated with shales intercalations. Ore deposit is explored by 308 boreholes (10509 m) and by numerous adits, inclines and crosscuts on the underground surface of 0.4 km2. From 1936 to 1941 and from 1953 to 1969 has been exploited 183000 t of ore with (in wt %): 34.0 SiO2, 2.9 Al2O3, 59.0 Fe2O3, 0.15 MnO, 0.7 CaO, 0.4 MgO, 0.1 P, 0.37 S, 1.25 l.o. ign. Proven remaining ore reserves are 250.000 t. Paragenesis is investigated by microscopy of thin and polished sections, XRD, DTA, AAS analyses and by sedimentological analyses. Paragenesis major minerals are of hematite and quartz, with subordinate stable lithoclasts, muscovite (sericite) and scarce kaolinite, calcite, dolomite, and barite. Accessories are zircon, rutile, tourmaline, amphibole, garnet, apatite. Epigenetic veinlets and small nests are built up of quartz or calcite as the main neominerals associated with siderite, barite, kaolinite, pyrite, gypsum. Iron from the Bukovica hematite ore originated by land weathering during hot climate and transported by rivers and underground waters deposited in river beds, in flood plains and in a shallow sea. Precipitation of the Bukovica iron ores took place after the Saalic orogenetic phase. At Hrastno (SE Slovenia) and at Rude nearby Samobor (Croatia), similar hematite deposits were found.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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