Faculty of Mining, Geology and Petroleum Engineering University of Zagreb
Abstract
Mineral relationships and their chemistry were studied in some basic magmatic rocks of Banija ophiolite complex. On the basis of mineral and structural characteristics three kind of rocks are distinguished: metadiabase I (being characterized by secondary amphibole), metadiabase II (being characterized by secondary albite) and spilite. Detailed chemistry of all mineral phases, specially of zoned clinopyroxenes and zoned amphiboles is given. The black opaque phases consist of different Fe-Ti-Mn oxides (ilmenite, Mn-ilmenite, magnetite, Ti-magnetite, ferropseudobrookite) being often at the rims replaced by Al- and Fe-rich titanite. All rocks are hydrothermally metamorphosed whereby amphibole replaced partly or completely clinopyroxene and plagioclase was altered in albite, prehnite, pumpellyite and/or sericite. Secondary chlorite occurs too. The whole rock chemistry of each studied rock corresponds to tholeiitic basalts.Međusobni odnosi minerala i njihova kemija proučavani su u nekim bazičnim magmatskim stijenama ofiolitnog kompleksa Banije. Na temelju mineralnih i stukturnih karakteristika razlikuju se tri vrste stijena: metadijabazi I (karakterizirani sekundarnim amfibolom), metadijabazi II (karakterizirani sekundarnim albitom) i spilit. Dana je detaljna kemija svih mineralnih faza, osobito zoniranih klinopiroksena i zoniranih amfibola. Crne opâke faze sastoje se od različitih Fe-Ti-Mn oksida (ilmenit, Mn-ilmenit, magnetit, Ti-magnetit, Fe-pseudobrukit) koje su često na rubovima potisnute Al- i Fe-bogatim titanitom. Sve su stijene hidrotermalno metamorfozirane pri čemu je amfibol djelomično ili potpuno potisnuo klinopiroksen, a plagioklas je izmijenjen u albit, prehnit, pumpeliit i/ili sericit. Pojavljuje se također i sekundarni klorit. Ukupna kemijska analiza svake proučavane stijene odgovara toleitskom bazaltu
