EXOTIC ORTHOGNEISS PEBBLES FROM PALEOCENE FLYSCH OF THE DUKLA NAPPE (OUTER EASTERN CARPATHIANS, POLAND)

Year, pages: 2005, 205 - 221

Crystalline exotic pebbles have been found in the deep-water flysch of the Cisna Beds, in the Dukla Nappe, Polish part of the Outer Western Carpathians. Most of them occur in a layer, which extends over a distance of at least 3 km within the SE limb of the Chryszczata–Wolosan–Mala Rawka anticline. The dimensions of the pebbles vary between 2 and 18 cm (middle axis). The exotic pebbles consist of three types of granite derived orthogneisses: 1 — medium-grained, medium-banded orthogneiss with alkali feldspar porphyroblasts showing structural features of foliated granitic-gneiss, 2 — medium-banded, medium-layered orthogneiss containing small microcline porphyroblasts and showing structural features of foliated granitic-gneiss, and 3 — strongly cataclastic granitic-gneiss with chess-board albite porphyroblasts showing properties of partly mylonitized granite. The chemical composition of the orthogneisses indicates that the protolith was represented by peraluminous, poorly-evolved, S-type granites exhibiting features of orogen-related crustal granites. The discrimination shows that the protolith of the studied rocks evolved in active continental margin or continental collision environments. The biostratigraphical data on deep-water agglutinated Foraminifera suggest the position of the exotic-bearing layer in the lowermost part of the Rzehakina fissistomata Zone corresponding to the lowermost Paleocene. Petrographic affinities between orthogneissic pebbles and mineral/rock fragments grains of the Cisna-type sandstones show that they have the same provenance. These deposits were transported from the NE extension of the Marmarosh massif, which had the character of a continental bearing source cordillera, formed mainly by orthogneissic and granitic rocks.

Bak, K., Wolska, A. 2005. EXOTIC ORTHOGNEISS PEBBLES FROM PALEOCENE FLYSCH OF THE DUKLA NAPPE (OUTER EASTERN CARPATHIANS, POLAND). In Geologica Carpathica, vol. 56, no.3, pp. 205-221. 1335-0552.

Bak, K., Wolska, A. (2005). EXOTIC ORTHOGNEISS PEBBLES FROM PALEOCENE FLYSCH OF THE DUKLA NAPPE (OUTER EASTERN CARPATHIANS, POLAND). Geologica Carpathica, 56(3), 205-221. 1335-0552.