Izvorni znanstveni članak
https://doi.org/10.17794/rgn.2026.5.15
HYDROMORPHIC BOG IRON ORE FORMATION IN FOOTHILL CAMBISOLS: MINERALOGICAL AND GEOCHEMICAL EVIDENCE FROM KNEZOVLJANI, CENTRAL CROATIA
Tomislav Brenko
; University of Zagreb Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, 10000 Zagreb, Croatia.
Sibila Borojević Šoštarić
; University of Zagreb Faculty of Mining, Geology and Petroleum Engineering, Pierottijeva 6, 10000 Zagreb, Croatia.
Tena Karavidović
; The Institute of Archaeology, Jurjevska ulica 15, 10000 Zagreb, Croatia
Tajana Sekelj Ivančan
; The Institute of Archaeology, Jurjevska ulica 15, 10000 Zagreb, Croatia
Sažetak
This study examines the formation and geochemical signature of Fe-rich horizons and bog iron-type accumulations in hydromorphic soils at Knezovljani, in the foothills of the Trgovska and Petrova gora massifs, central Croatia. A pedological trench with three soil profiles was described and sampled, with horizons and a hardened Fe-rich layer analysed using grain size analysis, X-ray diffraction (XRD), portable X-ray fluorescence (pXRF), with XRF and inductive couple plasma mass spectrometry (ICP-MS) for selected hardened Fe samples. The soils contain silt (50–75%) with 10–32% clay, are moderately acidic (pH 4.8–5.9), and they consist of quartz, feldspars, and illite–smectite clays with trace kaolinite, indicating intermediate weathering. One horizon shows pronounced Fe enrichment (33.8 wt% Fe2O3), with high contents of goethite and a laminated Fe-cemented facies, while other horizons contain only 5–9 wt% Fe2O3 . Trace elements are elevated in Fe-rich layers, with positive correlation towards Fe2O3 . Comparison with regional bog iron ores and Mn rich occurrences represents Knezovljani as a small, hydrologically focused Fe accumulation pocket formed where Fe bearing groundwater meets more oxidising conditions at a footslope of a hill, rather than in a microdepression. The Knezovljani Fe horizon is thin and discontinuous, indicating short-lived or spatially restricted Fe mobilisation–precipitation cycles. The findings highlight the importance of microtopography and subsurface flow in formation of secondary Fe ores, providing a framework for further studies on ore types, spatial distribution, and geochemical characterisation towards studies of bog iron ore in central Croatia.
Ključne riječi
hydromorphic soils; geochemistry; correlation matrix; pXRF; geoarchaeology
Hrčak ID:
352897
URI
Datum izdavanja:
27.10.2026.
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