The geochemistry of mafic metavolcanics: implications for the origin of the Devonian massive sulfide deposits at Zlaté Hory,Czechoslovakia

Mafic metavolcanic rocks in the area of the Zlaté Hory massive sulfide deposits are interpreted as convergent plate-margin basalts and basaltic andesites metamorphosed to the greenschist facies. According to the major- and trace-element compositions the metabasites exhibit island-arc tholeiitic to low-K, calc-alkaline composition.Approximately 50% of samples of maifc metavolcanics studied have a salient negative anomaly of Ce in chondrite-normalized REE patterns. The Ce-depleted greenschists are thought to represent hydrothermally altered equivalents of metabasites of island-arc tholeiitic composition. The alteration was accompanied by the sulfide mineralization. That is indicated by enrichment in Ba and S together with correlation of the Ce/Ce* values and CO₂ abundances in the Ce-depleted rocks. The Ce anomaly may be caused by alteraton of ore-forming, seawaterderived solutions. The occurrence of Ce-depleted greenschists supports the hypothesis of the volcanogenic origin of the ore deposits in the Zlaté Hory area.