Naslov
Ore forming fluids in Triassic, rifting related SEDEX deposits, Vares and Veovaca, Central Bosnia

Autori
Strmić, Sabina ; Palinkaš, Ladislav ; Prochaska, Walter

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
PANCARDI Meeting Abstracts / - , 2001, DP-16

Mjesto i datum
,

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
SEDEX deposit; Dinarides; fluid inclusion; barite; ion chromatography

Sažetak
Triassic SEDEX deposits are widespread in the Dinarides. SEDEX deposits in the Central Bosnia. (Vares metallogenic district) range from syngenetic, synsedimentary to epigenetic, vein and breccia types. Mineralization is derived from hydrothermal sea floor exhalations within a rift .depression of the Thetys. It is placed conformably within surrounding tuffs, tuffites, cherts, marly shales, limestones, occasionally accompanied by spilite and keratophyre pillow lavas. Deposition of the mineral load took place subterres- r trja11y, in the feeder zone within bottom sediments, or on the sea floor at proximal and distal depositional sites. Local environmental conditions, geomorphology of the sea floor, Eh-pH, pCO2, pH2S, temperature, pressure, etc., offer wide genetic varieties of mineral parageneses, from Fe-Mn, Mn-Fe (siderite, hematite, Mn-oxy-hydroxides) to barite and Fe-Pb-Zn (Hg) sulfides. Vares deposit is a typical stratiform mineralization of pyrite-barite-siderite-hematite-chert ores formed by exhalation of hydrotherms onto the bottom of rifting basin with steady increase of Eh and decrease of pH2S of the sea water. Veovaca is an epigenetic, breccia type of massive Fe-Pb-.Zn (Hg)-sulfides, deposited on the basinal slopes, what produced extensive intra-formational slumping. The presented research shows chemical characteristics of the ore-forming fluids, determined by fluid inclusion study and ionic chromatography. It also summarizes some previous geochemical data, obtained by other researchers, in order to constrain their chemistry. Sulphur isotopes. The δ 34S of barite from Vares varies from +20.7 to +28.6‰ (average +23.39‰ ), , whereas δ 34S of pyrite is -11.1‰ . Thirteen samples of barite from Veovaca have in average δ 34S +20.89‰ (KUBAT et al., 1979/80 ; SIFTAR 1988). SrSO4 content of barite from Vares varies from 1.2 to 3.5 wt. % (average 2.63 wt. % SrSO4), and in barite from Veovaca is 3.1 wt. % (KUBAT et al., 1979/1980 ; SIFTAR, 1988). Ionic chromatography measurements were performed on barite samples (micro quantity of Na-CI-Br in leaches of fluid inclusions, presented as the molar ratio of Na/Br and Cl/Br). The molar compositions of fluids from Vares are very close to sea water, whereas composition of fluids from Veovaca lie along "evaporation trend" The objects of microthermometric measurements (MT) and laser Raman spectroscopy (LRS) were performed on 0.2-0.3 mm thick barite wafers.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

Napomena
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