Mn-Fe mineralizations in Paleogene volcanogenic rocks from the area of Perperek village, Eastern Rhodopes: Geochemical features and formation conditions

Two Mn and Fe nodule bearing early Oligocene volcano-sedimentary sequences located to the north and north-west of Perperek village in the Eastern Rhodopes were studied. The main feature of the sequences is a manifold rhythmic alternation of medium to coarse grained sandstones and granule conglomerates intercalated by thin clayey layers. Two types of nodules: (i) oval, ochreous and red, Fe-bearing; (ii) spherical, black, Mn-bearing were studied. Mn nodules are composed of quartz, cristobalite, plagioclase, and holandite. Typical are high contents of Mn, Ba, Pb, V, Co, Mo, W, Tl, and REE. Fe nodules contain chamosite and show high content of Si and Al and P, V, Co, Cu, REE. Geochemical data support diagenetic origin of the studied Mn and Fe nodules.