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Mineral assemblage and provenance of the Pliocene Viviparus beds from the area of Vukomeričke Gorice (Central Croatia)

Viviparus beds are sediments deposited in lacustrine and fluvial freshwater environments (Lake Slavonia) during the Pliocene and the earliest Pleistocene. A detailed field study and mineralogical, petrographic and chemical analyses were carried out to determine their composition and origin in the area of Vukomeričke Gorice (Central Croatia). Viviparus beds are characterized by vertical and lateral exchange of mineralogically and chemically mature pelites and sands. Pelitic sediments consist mainly of detrital quartz, calcite, dolomite, and feldspar grains, and smectite as the most common clay mineral. Quartz and the most resistant lithic fragments dominate the sandy detritus. The composition of the sediments indicates their origin from the recycled orogen, while their structural immaturity suggests a short transport. Most of the material was re-deposited from the underlying Upper Miocene sediments of originally Alpine provenance. The smaller part originated from Paleogene sediments, Triassic carbonate rocks, basic or acidic magmatic rocks, and metamorphites. Medvednica and Žumberak Mts. were the most important source areas, while a smaller part of the material could have come from Moslavačka gora Mt. and Banovina region. The uniform composition of Viviparus beds over the entire vertical distribution of the sediments clearly indicates that the source areas didn’t change during their deposition. A significant change from structurally and mineralogically mature Upper Miocene clastic detritus of alpine origin to structurally immature material of Viviparus beds of local origin is consequence of compression and inversion of the previously extensional basin resulted in uplifting and erosion of the mountains inside of the SW part of Pannonian Basin System.

Viviparus beds , Pliocene, mineral assemblage, provenance

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