Aligning and synchronization of MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for DEEP core chronology

Abstract

Abstract. The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through the marine isotope stages (MIS) 15-1. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed palaeoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. Here, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically dated Mediterranean marine and continental proxy records. The alternative age model presented here shows consistent differences with that initially proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this new age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how a detailed study of independent chronological tie points is important to align different records and to highlight asynchronisms of climate events. Moreover, have incorporated the new chronology proposed for tephra OH-DP-0499 in the final DEEP age model. This has reduced substantially the chronological discrepancies between the DEEP site age model and the model proposed here for the last glacial-interglacial transition.

Pollen-based temperature and precipitation changes in the Ohrid Basin (western Balkans) between 160 and 70 ka

“…However, TOC reflects autochthonous and allochthonous organic matter input, i.e. supply of biomass from both the lake as well as the surrounding land Holtvoeth et al, 2017;Zanchetta et al, 2018). The productivity of the terrestrial vegetation and supply of terrestrial organic matter to the lake seem to be largely controlled by precipitation rather than temperature; thus, explaining similarities with the PANN record.…”

“…Lake Ohrid's chronology is well established for MIS 5 due to the high number of tephra layers Leicher et al, 2016), in particular for the transition between the Riss glaciation and the Eemian, for which a further correlation with geochemical and pollen data from Lake Ohrid and other proxies from Mediterranean sequences was carried out by Zanchetta et al (2016). For other European pollen records such chronological constraints are not available and thus the chronologies are probably less precise.…”

Reply letter

“…4.3.2) and climate change over the last 92 kyr . However, the potential for a regime shift increases with recent human impact on the diatom flora of both lakes Ohrid (Zhang et al, 2016) and Prespa although, again, Ohrid appears to be more well-buffered from eutrophication than Prespa.…”

“…Although the Co1262 sediment sequence reached only 10.08 m b.l.f., this is the most complete Holocene sequence retrieved to date. Studies on the core material contributed to a better understanding of the tectonic activity and the Late Glacial to Holocene environmental history of the region Zhang et al, 2016).…”

“…Nonetheless, though environmental changes may have had only a minor direct effect on diversification processes in endemic taxa of Lake Ohrid during the last 637 kyr, these changes potentially altered the abundance and community compositions of diatoms and ostracods (e.g. Belmecheri et al, 2010;Reed et al, 2010;Zhang et al, 2016), thus indirectly affecting speciation processes. In fact, the analysis of the gastropod community in Lake Ohrid implied the presence of both geographical and ecological speciation due to physical barriers and divergence across environmental or life history gradients, respectively .…”