A 2800-year multi-proxy sedimentary record of climate change from Lake Çubuk (Göynük, Bolu, NW Anatolia)

Abstract

The sediment of Lake Çubuk in NW Anatolia, which is situated very close to the climate boundary between the dry Central Anatolia and the wet Marmara region, is regarded as a suitable climate archive to test inward and outward movements of this boundary in accordance with past climate variations. Herein, we study the stratigraphic record of the last 2800 years of this landslide-dammed lake at 1030 m elevation, using multi-proxy tools (sedimentology, major and trace element geochemistry, stable isotopes, pollen, diatoms and ostracods) and compare the results with other contemporaneous Anatolian climatic records. Our findings indicate that Lake Çubuk recorded seven distinct climatic periods in the last 2800 years that have been previously revealed elsewhere in Anatolia. The most arid period occurred at the end of the Near-East Aridification Phase at approximately 200 BC when the δ 18 O shifted to very negative values, and the planktonic diatom ratio considerably decreased. The Dark Ages and the late Byzantine periods between AD 670 and 1070 are characterized by more positive δ 18 O values, increasingly higher lake levels and the most extensive arboreal cover of the entire record. The 'Little Ice Age' appeared suddenly, within 40 years, at AD 1350 and is reflected in all of the proxies, including a positive shift in δ 18 O, a sharp decrease in pollen of shrub and herb to the benefit of pine trees and a rapid increase in benthic diatom abundance indicating a lake level shallowing. In many parts of the record, a close match between the stable isotopes and the pollen assemblage zones in the last 2800 years demonstrates that climate rather than human activity was the primary driver of vegetation cover in this mid-altitude mountain of NW Anatolia.

Fluvial response to rising levels of the Black Sea and to climate changes during the Holocene: Luminescence geochronology of the Sakarya terraces

“…Stalagmite records from the Kocain cave (labeled 4 in Figure 6, Göktürk, 2009) show a decrease in δ 13 C values and advocates increased precipitation. Evidence for wet conditions is also reported from Çubuk Lake (Ocakoğlu et al, 2016; labeled as 5 in Figure 6). Borehole GeoB-7622 from the Black Sea shelf (Lamy et al, 2006; labeled 6 in Figure 6) recorded a significant increase in clay layer frequency correlated with negative AO/NAO climatic phases and associated increases in the Sakarya River discharge and thus sediment flux.…”

“…This depositional period corresponds to the late Antiquity (Medieval) Dark Ages (Drake, 2012) and also the Oort solar minimum event, reflected as shifts (increases) in Uzuntarla, Kocain and Sofular Cave δ 13 C values and related to decrease in precipitation (Göktürk, 2009). This is interpreted as a dry period in the Lake İznik and Çubuk (Ocakoğlu et al, 2016;Ülgen et al, 2012) records. It also corresponds (with a 200 year time shift) to an increase in Lake Nar δ 18 O record (Jones et al, 2006; 8 in Figure 6), while Izdebski et al (2016) reported that shift to drier conditions in Anatolia occurred at ~AD 730 and related to early Medieval drought.…”

Lake Neor reveals how mountain vegetation responded to 7000 years of hydroclimate variability in northwestern Iran

“…In contrast, most records from the eastern Mediterranean propose a dry climate for this interval (e.g. Roberts et al ., 2001, 2008; Schilman et al ., 2001; Wick et al ., 2003; Kaniewski et al ., 2008; Ocakoğlu et al ., 2016; Ramezani et al ., 2020). Nevertheless, palynological study from the southern Caucasus (Messager et al ., 2013; cf.…”

“…Studying sediments from the Aegean Sea, Ehrmann et al ., (2007) inferred a dry period lasting from 1700 to 1000 cal a bp for the north and south catchments of the sea. Also, palaeoclimate reconstruction studies in Anatolian lakes suggest centennial‐scale dry climatic conditions for the period between 1800 and 1300 cal yr bp (see Ocakoğlu et al ., 2016).…”

Holocene paleoenvironmental evolution of the Acıgöl paleo maar lake (Nevşehir, Central Anatolia)

“…Therefore, many studies have been realised on Neogene-Quaternary archive records of the fossil lakes and/ or ponds of Anatolia to determine the ostracod fauna. Studies on Quaternary deposits (Şafak and Taner 1998;Beker et al 2008;Meriç et al 2009;Tunoğlu et al 2012;Ocakoğlu et al 2013Ocakoğlu et al , 2016Tuncer and Tunoğlu 2015;Karayiğit et al 2016;Tuncer et al 2017;Berndt et al 2019a, b;McCormack et al 2019) are rare by comparison with European/ Palearctic counterparts (Scharf 1983(Scharf , 1993Ricci Lucchi et al 2000;Viehberg 2004;Scharf et al 2005;Wilkinson et al 2005;Pipík and Bubik 2006;Meidla 2009, 2010;Anadón et al 2012;Bellucci et al 2012;Kalbe et al 2015;Mazzini et al 2015;Hajek-Tadesse et al 2018).…”