Vegetation and climate of the early-middle miocene coal-bearing sediments in the eski̇şehi̇r graben (Eski̇şehi̇r-Ağapınar and Eski̇şehi̇r-Alpu wells)

In this study, paleoecology of the Early-Middle Miocene lignite-bearing sediments had been surveyed around Eskişehir. Palinological simples were obtained from two drilling cores, Eskişehir-Alpu (230m) and Eskişehir-Ağapınar (36m). Sequence usually comprises of sandstone, mudstone, conglomerate and coaly levels. Palaeozoic metamorphites and Mesozoic ophiolites comprise the basement rocks. Miocene lignite-bearing sediments unconformably overlie these basement rocks and comprise of m1,m2,m3 series from bottom to top. Palinological communities come by lignite levels situatedunder and above of the series of m2. The communities Taxodiaceae/Cupressaceae, undifferentiated Pinaceae, Osmunda, Alnus, Pinus haploxylon type, Polypodiaceae and Castanea-Castanopsis forms are in high percentages. Communities consist dominantly of conifer forest assemblages and riparian plants. On the other hand, the broad-leaved forest and mixed forest association are in low percentage. Palynological data indicate a dense forest cover and marsh environment in the source area. Small quantities of herbareous plants such as Ephedraceae, Poaceae and Chenopodiaceae may indicate periods of drought dry periods during the deposition. Quantitative paleoclimate data states that mean annual temperature is between 17.2-31.3 oC, winter temperature ranges between 5.6-12.5 oC and summer temperature ranges between 27.3-27.9 oC. Quantity of annual rainfall exceeds 1300 mm. Precipitation of driest month is between 7 and 41 mm, precipitation of warmest month is between 204 and 227 mm and summer rainfall is between 118 and 125 mm. According to obtained palynological data, deposition of lignite-bearing sediments in the Eskişehir Basin occured in damp and warm climate conditions. These data show us that around Eskişehir had been warm through Early-Middle Miocene and it had received more precipitation than the present day climatic conditions. Keywords: Alpu, Ağapınar, Early-Middle Miocene, Eskişehir, Palynology, Palaeoclimate.