Petrological and geochemical characterization of Ge-bearing coals from the eastern Rhodopes, Bulgaria

Jérôme Gouin (1, 2) , Catherine Lerouge (2) , Yves Deschamps (2) , David Widory (2) , Fatima Laggoun-Défarge (1) , Mariana Yossifova (3) , Yotzo Yanev (3)

1 ISTO - Institut des Sciences de la Terre d'Orléans
2 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
3 Geological Institute of BAS

The coals from Pchelarovo and Vulce Pole are perhydrogenated coals showing high sulphur content (3.2 - 6.2 wt%) and significant Ga and Ge contents (0 - 480 ppm) in organic matter (OM). The coals from Medenbuk could be perhydrogenated coals modified by weathering processes. They show low sulphur content (1.5 wt%), high homogeneous Ge contents in OM (~2500 ppm) and an unusual enrichment in Ge (up to 0.8 wt%) and V (2.8 wt%) in weathered zones of framboïdal pyrite. Sulphur isotopic study of pyrite and organic sulphur provides evidence of bacterial reduction of dominantly seawater sulphates. However taking account the geological context of the three basins, the introduction of volcanic fluids in the basins of Pchelarovo and Vulce Pole during their forma-tion cannot be excluded.

Keywords: coal geochemistry; germanium; sulphur isotopes; eastern Rhodopes; Bulgaria

Domains: Geochemistry

Jérôme Gouin, Catherine Lerouge, Yves Deschamps, David Widory, Fatima Laggoun-Défarge, et al.. Petrological and geochemical characterization of Ge-bearing coals from the eastern Rhodopes, Bulgaria. Mineral Exploration and Research : Digging Deeper, Aug 2007, Dublin, Germany. 4 p. ⟨insu-00155009⟩