ALBERT

Description: Lake Ohrid (Macedonia, Albania) is thought to be more than 1.2 million years old and host more than 300 endemic species. As a target of the International Continental scientific Drilling Program (ICDP), a successful deep drilling campaign was carried out within the scope of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) project in 2013. Here, we present lithological, sedimentological, and (bio-)geochemical data from the upper 247.8m composite depth of the overall 569m long DEEP site sediment succession from the central part of the lake. According to an age model, which is based on 11 tephra layers (first-order tie points) and on tuning of bio-geochemical proxy data to orbital parameters (second-order tie points), the analyzed sediment sequence covers the last 637 kyr. The DEEP site sediment succession consists of hemipelagic sediments, which are interspersed by several tephra layers and infrequent, thin (〈 5 cm) mass wasting deposits. The hemipelagic sediments can be classified into three different lithotypes. Lithotype 1 and 2 deposits comprise calcareous and slightly calcareous silty clay and are predominantly attributed to interglacial periods with high primary productivity in the lake during summer and reduced mixing during winter. The data suggest that high ion and nutrient concentrations in the lake water promoted calcite precipitation and diatom growth in the epilimnion during MIS15, 13, and 5. Following a strong primary productivity, highest interglacial temperatures can be reported for marine isotope stages (MIS) 11 and 5, whereas MIS15, 13, 9, and 7 were comparably cooler. Lithotype 3 deposits consist of clastic, silty clayey material and predominantly represent glacial periods with low primary productivity during summer and longer and intensified mixing during winter. The data imply that the most severe glacial conditions at Lake Ohrid persisted during MIS16, 12, 10, and 6, whereas somewhat warmer temperatures can be inferred for MIS14, 8, 4, and 2. Interglacial-like conditions occurred during parts of MIS14 and 8.

Description: This dataset presents the chronological framework, (bio-)geochemical, mineralogic stable isotope, pollen, and tephrochronologic data of the upper 448 m of the DEEP site (5045-1) sediment sequence recovered from the central part of Lake Ohrid (Macedonia, Albania) under the umbrella of the International Continental Scientific Drilling Program (ICDP) and the project Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO). The investigated interval comprises fine-grained muds with intercalated tephra layers and mass movement deposits of mostly less than 5 cm thickness. Two tephra layers of thicknesses more than 5 cm were excluded prior to age-depth modelling, which is based on tephrostratigraphy, tephrochronology, magnetostratigraphy, and tuning of biogeochemical proxy data versus local orbital parameters. (Bio-)geochemical analyses comprise X-Ray fluorescence scanning at 2.5 mm resolution (Potassium and Calcium intensities), and total inorganic carbon (TOC) and total organic carbon (TOC) determinations at 16 cm resolution. The relative abundance of quartz minerals (Quartz peak area, 16 cm resolution) was detected by means of Fourier Transform Infrared Spectrometry (FTIRS). Oxygen and carbon stable isotope were analysed on (interglacial) sediments where endogenic calcite crystals were found to be abundant. Pollen data presented herein at 64 cm resolution comprise a sub-dataset of the total pollen counts and presents relative percentages of arboreal taxa minus pine (AP-pine), and of deciduous oaks, respectively. Tephrochronologic data comprises geochemical fingerprint analyses of individual glass shards found in the sediments of Lake Ohrid, and a new Ar/Ar age for tephra V5 from the Montalbano Jonico section. Climate time series data are derived from a transient 784 ka simulation using the earth system model LOVECLIM as well as NOAA reanalysis precipitation data of the Lake Ohrid region for the tim period 1979-2017.