Open AccessSi-P impure Al-Goethite Mineralization on the island of Dugi Otok (Central Adriatic, Croatia)
Author(s) -
Branimir Šegvić,
Boško Lugović,
Neven Tadej,
Vladimir Bermanec,
Lovro Panjkota
Publication year - 2008
Publication title -
geologia croatica online/geologia croatica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.226
H-Index - 28
eISSN - 1333-4875
pISSN - 1330-030X
DOI - 10.4154/gc.2008.04
Subject(s) - goethite , geology , mineralization (soil science) , geochemistry , metamorphic rock , calcite , carbonate , mineralogy , cretaceous , chemistry , materials science , metallurgy , paleontology , organic chemistry , adsorption , soil science , soil water
At the western seaward coast of the island of Dugi Otok, unusual goethite mineralization occurs as the infilling of a system of thin crevices in the Upper Cretaceous limestones of the Adriatic carbonate platform. Goethite is exceptionally well ordered and shows a variety of chemical compositions ranging from almost pure FeO·OH to Al-substituted composition accompanied by high Si and P impurity. The most characteristic textural type assemblages are goethite and coarse grained calcite in composite aggregates. These aggregates contain Al-substituted goethite with metamorphic silicate minerals embedded in the core, (black goethite) armoured by the XRD-pure, almost stoichiometric goethite (brown goethite). The geochemical and mineralogical features of the mineralization suggest an ascending solution from a hidden metamorphic source. We speculate that the source could have been activated by the thermal influx linked to the Pliocene intraplate magmatism in the eastern segment of Adria.