Palaeovegetational evolution of the Çankırı-Çorum Basin during the Mio-Pliocene (Central Anatolia) based on the IPR analysis method

Abstract

Reconstruction of past vegetation and climates in the Cankiri-Corum Basin, one of the largest basins of Central Anatolia, is important for understanding the regional palaeovegetation. In this study, the palaeovegetational and palaeoclimatic proxies of the basin within the late middle Miocene and early Pleistocene interval are presented using the Integrated Plant Record (IPR) vegetation analysis and the coexistence approach (CA). The IPR analysis allows the reconstruction of six types of zonal vegetation: broad-leaved deciduous forests (BLDF), mixed mesophytic forests (MMF), broad-leaved evergreen forests (BLEF), xeric open woodlands and xeric grasslands or steppes, all identified from the microfloras of Cankiri-Corum Basin. During the late middle Miocene, warm temperate and humid climatic conditions prevailed and the palaeovegetation in the Cankiri-Corum Basin was represented by BLEF and an ecotone between MMF and BLEF. The cooling from the late middle Miocene to early late Miocene had begun as well, as low precipitation periods in the climatic conditions during the same time interval were recorded in the basin. Presumably, the proportion of broad-leaved deciduous elements remained balanced because the palaeotopography did not change significantly during the late Miocene in the Cankiri-Corum Basin. The recorded cooling could be related to a global climatic change from the middle to late Miocene. During the Tortonian to Messinian transition, the palaeovegetation type was represented by BLDF and suggests a continuous cooling trend in the basin. The palaeovegetation types of the late late Miocene comprise MMF in the northern part of the Cankiri-Corum Basin and xeric grassland or steppe in the southern part of the basin. Warm and dry climatic conditions were recorded from the Tortonian to the Messinian; these warm conditions during the Messinian could be correlated to the Messinian salinity crisis. According to the IPR analysis results, the northern part of the Cankiri-Corum Basin palaeotopography seems to be higher in altitude than the southern part. Palaeovegetation types in the latest late Miocene and early Pliocene were characterised by MMF and an ecotone between BLDF and MMF in the northern part of the Cankiri-Corum Basin and open woodland vegetation in the southern part of the basin. The percentage of the broad-leaved deciduous component from the latest late Miocene and early Pliocene decreases in the Cankiri-Corum Basin, which could be related to beginning uplift starting changes in the palaeotopography. In the early Pliocene, this uplift was continued in the basin.