Index Geophysics

eng SEDIMENTARY LOW-MANGANESE HEMATITE DEPOSITS OF THE BUKOVICA AREA IN THE NORTHWESTERN MT. PETROVA GORA, CENTRAL CROATIA

hrv SEDIMENTNA LEŽIŠTA HEMATITA S MALIM UDJELOM MANGANA NA PODRUČJU BUKOVICE U SJEVERNOZAPADNOM DIJELU PLANINE PETROVA GORA, SREDIŠNJA HRVATSKA

eng Middle-Permian Gröden deposits crop out on the surface of 0.8 km in the Bukovica area and on the surface of 0.8 km2 in the Mt. Loskun-jska 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 stretch¬ing vertical, normal and reverse faults. The hematite bed is unconfor-mably 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 Si02, 2.9 Al2O3; 59.0 Fe203; 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 litho-clasts, 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 origi¬nated by land weathering during hot climate and transported by rivers and underground waters deposited in river beds, in flood plains and in 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.

hrv Srednjopermski Gröden sedimenti pokrivaju površinu od 0.8 km u području Bukovice i 0.8 km u planini Loskunja u SZ dijelu Petrove gore. Oko polovine Gröden naslaga u Bukovici sadrži u svojim najdon-jim dijelovima 1-5 m (u prosjeku 2,5 m) debeo sloj hematita rasjedan u blokove vertikalnim, normalnim i reversnim rasjedima pružanja NE-SW. Sloj hematita leži nesukladno na donjopermskim kvarcnim grejvakama (subgrejvakama) s interkalacijama šejlova. Rudno je ležište istraženo sa 308 bušotina (10509 m) i brojnim potkopima, galerijama, prečnicima i niskopima na podzemnoj površini od 0,4 km2 . Od 1936. do 1941. te od 1953. do 1969. izvađeno je 183000 t rude sa (u mas %) 34,0 Si02; 2,9 Al2O3; 59,0 Fe203; 0,15 MnO; 0,7 CaO; 0,4 MgO; 0,1 P; 0,37 S i 1,25 g.ž. Dokazane preostale rezerve iznose 250 000 t. Parageneza je istražena mikroskopski u providnim i rudnim preparatima, s XRD, DTA, AAS analizama te sedimentološkim anali¬zama. Glavni minerali su kvare i hematit s podređenim stabilnim litoklastima, muskovitom (sericitom), oskudnim kaolinitom, kalcitom, dolomitom i baritom. Akcesorije su cirkon, rutil, turmalin, amfibol, granat, apatit. Epigenetske žilice i mala gnjezdašca izgrađena su od kvarca ili kalcita kao glavnih neominerala asociranih sa sideritom, baritom, kaolinitom, piritom i gipsom. Željezo hematitnog ležišta Bukovica potječe iz kore trošenja na kopnu za vrijeme vruće klime i transportirano je rijekama i podzemnim vodama te taloženo u koritima rijeka, naplavnim ravnicama i u plitkim unutarnjim morima. Taloženje željezne rude u području Bukovice nastalo je nakon salske orogene faze. Kod Hrastnog (JI Slovenija) i kod Ruda blizu Samobora (Hrvat¬ska) nađena su slična hematitska ležišta.

Čop, Milivoj

Jurković, Ivan

Slovenec, Dragutin

eng Middle-Permian low-manganese hematite deposits;geotectonic setting;XRD, AAS, DTA analyses;morphology;paragenesis;genesis; Bukovica;Croatia

hrv Srednjopermska niskomanganska hematitska ležišta;geotektonski položaj;XRD, AAS, DTA analize;morfologija;parageneza;geneza;Bukovica;Hrvatska

Faculty of Mining, Geology and Petroleum Engineering University of Zagreb

1998

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Rudarsko-geološko-naftni zbornik

ISSN 1849-0409 (Online)

Volume 10

Issue 1

eng

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