| Popis: |
The Pikermian chronofauna is associated with C4 vegetation and the potential hominin Graecopithecus freybergi in Greece and Bulgaria and forms part of the Old World Savannah Paleobiome. This study provides a new magnetostratigraphy for thestratigraphic interval that includes the Haliminhanı and Hayranlı mammal sites from the central Anatolian Sivas Basin (Turkey), which show high faunal similarities to the Pikermian chronofauna.Dated sites harboring Pikermian fauna in Turkey, Greece, and Bulgaria range in age between 11 and 7.3 Ma. Based on biostratigraphy, the Haliminhanı and Hayranlı fossil horizons were previously placed within European Mammal Neogene (MN) zones MN11-MN12 (ca. 9 to 7 Ma). A new magnetostratigraphy in 140 m thick continental deposits refines the age estimate to 8.0–6.5 Ma for the fossil mammal-bearing levels of the Sivas Basin.Negative covariance between δ13C and δ18O values of bulk carbonate from the fluvio-lacustrine beds indicates an open lake hydrology; δ13C and δ18O values suggest a positive water balance and no significant long-term changes in hydrology and primary productivity within the lake that once covered the Sivas Basin. Two intervals of increased δ13C (by ca. 6–8‰) within the section are followed by a similar decrease over total time intervals of ca. 150 kyr. An increase of biogenic productivity can increase δ13C in lacustrine carbonate and may either result from changes in nutrient input or temperature. The absence of simultaneous changes in δ18O during peaks in δ13C make temperature an unlikely driver and we therefore conclude that nutrient input adjustments to the basin were responsible for the two peaks in δ13C.Our results suggest that the Pikermian chronofauna of the Sivas Basin thrived under relatively stable local hydrological and climatic conditions. In the Sivas Basin, the Pikermian fauna flourished well into the Messinian, as opposed to Greek and Bulgarian sites where faunal turnover was observed under a cooling climate and mid-latitude desertification across the Tortonian-Messinian boundary.Key words magnetostratigraphy, stable isotope geochemistry, mammal stratigraphy, late Miocene, Pikermian, central AnatoliaReferences Böhme et al. (2017). PLoS ONE, https://doi.org/10.1371/journal.pone.0177347; Böhme et al. (2018). Global and Planetary Change, https://doi.org/10.1016/j.gloplacha.2018.07.019 ; Meijers et al. (2018). Earth and Planetary Science Letters, https://doi.org/10.1016/j.epsl.2018.05.040; Meijers et al. (2020). Geosphere, https://doi.org/10.1130/GES02135.1; Meijers et al. (2022). Newsletters on Stratigraphy, https://doi.org/10.1127/nos/2021/0623 |
