Palaeoflora of Kamenica (Pranjani Basin, western Serbia)

ivana.vasiljevic@rgf.bg.ac.rs Abstract. Palaeofloras of the Paleogene in Serbia are relatively rare, especially in comparison with floras from Neogene sediments. Most Paleogene phytoassociations from the territory of Serbia existed in a dry and warm climate. The youngest Paleogene phytoassociation originates from the Pranjani Basin (Western Serbia), locality Kamenica. The age of this palaeoflora is determined as Late Oligocene. This fossil plant assemblage is different from other Paleogene phytoassociations.The palaeoflora from Kamenica is characterized with leaf imprints larger than in other Paleogene fossil floras. Furthermore, it differs in taxonomical composition. The prevailing forms are conifers and representatives of broad-leaved evergreen forests. In other Paleogene phytoassociations, elements of broad-leaved evergreen forests are extremely rare. The dominating elements in the palaeoflora of Kamenica are the conifers, especially Glyptostrobus, Pinus, Sequoia and Tetraclinis. The representatives of the broad-leaved evergreen forests are Laurus, Magnolia, “Quercus”, etc.


Introduction -geological setting
The Pranjani Basin is part of the West Morava Graben (also known as the Čačak-Kraljevo Basin).
Located on the northwestern border of the Ča čak-Kraljevo Basin, the Pranjani Basin covers an area of 45 km 2 and is elongated in an east-west direction (Fig. 1). On the southeast it is limited by the slopes of Maljen and Suvobor, while the north side is framed by peridotit-serpentine massif. (ereMIja et al., 1977).
according to the changes of lithological composition it is possible to divide the Pranjani Basin into three horizons: The oldest horizon is located in the western part of the basin (the village of Kamenica) and it consists of well cemented conglomerates and breccias lying directly over the peridotite-serpentine rock. above them is a sequence of alternating sandstones, conglomerates and marlstones. Well preserved remains of fossil plants and fish have been found in these sediments. The second horizon is a "multicoloured series",of a depth of about 100 m. There is no observed direct contact with the layers of the older horizon. This horizon is composed of sandstones and sands with thin layers of conglomerates, dolomitic limestones and shales as well as one intercalation of tuffits. The third horizon consists of marls and shales (ereMIja et al., 1977).
The fossil fish Smerdis minutus (BLaINvILLe) (aN -đeLKOvIć, 1989) was found in the first horizon's marls. This finding confirms the Oli gocene age of the sediments. The remains of the fossil plants, which are the subject of this paper, originate from the same sediments.
Based on fossil fish finding and comparison with other similar early Miocene floras, the deposits of the first horizon probably correspond to the upper parts of the Late Oligocene-early Miocene.
The Zapadna Morava Gra ben, also known as the Čačak-Kraljevo Basin, is the largest Intradinaric depression which extends NW-Se. Block downthrows along NW-Se faults and later ruptures of e-W and some of Ne-SW trends, controlled the formation of the Graben and its geometry. a characteristic of the Zapadna Morava Graben is the large subsidence of the Ottnangian-Karpatian, probably superposed upon similar movements of the Oligocene-Miocene. The central Graben sank the most, over a relatively wide area. (MarOvIć et al., 2007). a gravity anomaly map ( Fig. 2) was compiled in order to check the correlation between the position of Neogene basins and the distribution of gravity anomalies. Neogene basins are filled with sediments of low density, in comparison to the density values of the basement and surrounding rocks. In the presented study area (Fig. 2), the position of Neogene basins mostly coincides with low gravity values, but it is not a general case. Gravity anomalies are strongly influenced by the complex configuration of the basin basements and surrounding geology, implying a relatively shallow basin depth. The location of the Kamenica paleontological site is in a zone of abrupt changes of gravity anomaly values, probably    Kamenica (pink dot) in the vicinity of a steep (gravitational or reverse) fault of Se-NW direction.
The Paleogene and Neogene deposits in last few years were investigated from different aspects (e.g. đOrđevIć-MILuTINOvIć, 2018;radOvIć, 2018;jOvaNOvIć et al., 2019a, b) and this paper is one more contribution to knowledge of these deposits.

Palaeofloristic composition:
The leaf imprints, presently being studied, originate from dark-gray, very compact marls which lie across the serpentine. These sediments are characterized with considerable depth.

Palaeoecology and palaeoclimatology
about one hundred leaf imprints have been collected at the Kamenica locality. considering the relatively small number of specimens, there is a rich taxonomical diversity (Table 1).
analyzing the character of the leaf imprints morphology it can be observed that leaves with entire margin and brochidodromous or eucamptodromous venation, which correspond to subtropical dendroflora, prevail (categorization WOLFe, 1971 Fig. 10). These plant forms inhabited the banks of the river and the margins of the lake basin. a significant number of samples in this locality belongs to pines: Pinus hepios (Plate 1 Fig. 5 Based on the taxonomical composition of palaeophytoassociation and leaf morphology, it has been inferred that the climate was subtropical and humid during the existence of this plant association (WOLFe, 1971;WILF,1997;TraISeret al., 2005).

Comparisons between the flora of Kamenica and other Oligocene and Early Miocene floras in Serbia
The palaeoflora of Kamenica has been compared to the Oligocene and Lower Miocene floras from the territory of Serbia. Palaeovegetation from Kamenica differs from other Oligocene floras due to the existence in a wetter climate. The climatic conditions in the period when the Kamenica palaeophytoassociatione xisted were much more similar to those of the early Miocene. The taxonomic composition of the palaeoflora of Kamenica is a mix of Late Oligocene and early Miocene floras from Serbia.
The Late Oligocene flora of Bogovina (PaNTIć & PavLOvIć, 1977) from eastern Serbia is a palaeophytocoenosis of subtropical-tropical climate. In this palaeoflora conifers prevails, especially Sequoia but broad-leaved elements are rare. In this palaeophytoassociation dominate xeromorphic leaves from angiosperms.
In the Oligocene flora of divljana (Koritnica Basin -Southeastern Serbia) (MIhajLOvIć, 1985) xerophytes Ziziphus ziziphoides (uNGer) Weyland predominate. contrary to the flora of Kamenica, there are also, rare humid forms and numerous xeromorphic elements of vegetation in the palaeovegetation of divljana.
The palaeoflora of Kamenica is not as arid as most of Oligocene floras in Serbia. In most of Oligocene floras of Serbia, the dominant element is xerophytic Ziziphus ziziphoides, of which there are only two specimens in the Kamenica palaeoflora.
Lower Miocene floras of Serbia, such as the flora from the valjevo-Mionica basin (Western Serbia) (PaNTIć, 1956;LaZarevIć et al., 2013), Žagubica basin (eastern Serbia) (MILOvaNOvIć & MIhajLOvIć, 1984;LaZarevIć & MILIvOjevIć, 2010) and Popovac (central Serbia) (PaNTIć, 1956;LaZarevIć, 2008) are typically broad-leaved evergreen vegetation. In these palaeofloras Lauraceae, especially Daphnogene predominate. conifers are more abundant in the Kamenica palaeoflora than in most of the early Miocene floras of Serbia. during the early Miocene paleoclimatic conditions in Serbia were warm and humid as can be inferred from the vegetation of that time. The flora of Kamenica also indicates the subtropicaltropical, humid character of the climate. Palaeovegetation of Kamenica is distinguished from the early Miocene floras by a rare representation of Daphnogene and lower proportion of elements of evergreen broad-leaved vegetation.

Conclusions
Palaeofloras of the Paleogene in Serbia are relatively rare, especially in comparison with floras from Neogene sediments. Most Paleogene phytoassociations from the territory of Serbia existed in dry and warm climate. The youngest Paleogene phy- toassociation originates from the "Pranjani Basin" (Western Serbia), locality Kamenica. The age of this palaeoflora is determined as the Late Oligocene based on fish fossil and comparison with other similar floras of Oli gocene and early Miocene in Serbia. This fossil plant assemblage is different from other phytoassociations of Paleogene and early Miocene. The climatic conditions in the period when the Kamenica palaeophytoassociation existed were much more similar to those of the early Miocene. The taxonomic composition of the palaeoflora of Kamenica is a mix of Late Oligocene and early Miocene floras from Serbia.
Paleoclimate estimates derived from the woody dicotyledonous angiosperm from the Kamenica locality indicate the climate was warm and humid, subtropical-tropical.
Such favorable environmental and climatic conditions were reflected in the vigour of vegetation in the Late Oligocene. WILF, P. 1997