Sedimentary evolution and environmental history of Lake Van (Turkey) over the past 600 000 years

Abstract

The lithostratigraphic framework of Lake Van, eastern Turkey, has been systematically analysed to document the sedimentary evolution and the environmental history of the lake during the past ca 600 000 years. The lithostratigraphy and chemostratigraphy of a 219 m long drill core from Lake Van serve to separate global climate oscillations from local factors caused by tectonic and volcanic activity. An age model was established based on the climatostratigraphic alignment of chemical and lithological signatures, validated by 40 Ar/ 39 Ar ages. The drilled sequence consists of ca 76% lacustrine carbonaceous clayey silt, ca 2% fluvial deposits, ca 17% volcaniclastic deposits and 5% gaps. Six lacustrine lithotypes were separated from the fluvial and event deposits, such as volcaniclastics (ca 300 layers) and graded beds (ca 375 layers), and their depositional environments are documented. These lithotypes are: (i) graded beds frequently intercalated with varved clayey silts reflecting rising lake levels during the terminations; (ii) varved clayey silts reflecting strong seasonality and an intralake oxic-anoxic boundary, for example, lake-level highstands during interglacials/interstadials; (iii) CaCO 3 -rich banded sediments which are representative of a lowering of the oxic-anoxic boundary, for example, lake level decreases during glacial inceptions; (iv) CaCO 3 -poor banded and mottled clayey silts reflecting an oxic-anoxic boundary close to the sediment-water interface, for example, lake-level lowstands during glacials/stadials; (v) diatomaceous muds were deposited during the early beginning of the lake as a fresh water system; and (vi) fluvial sands and gravels indicating the initial flooding of the lake basin. The recurrence of lithologies (i) to (iv) follows the past five glacial/interglacial cycles. A 20 m thick disturbed unit reflects an interval of major tectonic activity in Lake Van at ca 414 ka BP. Although local environmental processes 1830

Microbial abundance in lacustrine sediments: a case study from Lake Van, Turkey

“…Sediment properties like porosity or permeability are highly variable at both Lake Van sites due to rapid changes from laminated sediments to chaotic, mass-wasting sediments of variable composition and tephra layers of variable thickness. All lithologies can be found at both sites (Stockhecke et al 2014), albeit in variable thickness and stratigraphic position. Still, at any given depth, cell abundance at both sites is very similar, independent of lithology in the respective sample.…”

“…In summer 2010, long sediment cores were retrieved from two sites, recording palaeoenvironmental changes of the last 600 ky in this climate-sensitive area (Litt et al 2009;Stockhecke et al 2014).…”

Seismotectonics and rupture process of theMW 7.1 2011 Van reverse-faulting earthquake, eastern Turkey, and implications for hazard in regions of distributed shortening

“…The recent International Continental Drilling Project (ICDP) PALAEO-VAN project has focused on coring the varved sediments from two locations within Lake Van (Litt et al 2009(Litt et al , 2012Cukur et al 2014;Litt & Anselmetti 2014;Stockhecke et al 2014). Work is ongoing to establish the chronology, but Litt et al (2009) observe extensive seismites in the test drill cores, attributing them to the repeated occurrence of earthquakes throughout the last 500 ka.…”

Abrupt climate and vegetation variability of eastern Anatolia during the last glacial

“…By adding radiometric dating techniques, the Lake Van chronology was correlated by using "age control points", derived from visual synchronization with the GICC05-based NGRIP isotope data for this relevant interval (0-116 ka;NGRIP members, 2004;Rasmussen et al, 2006;Svensson et al, 2008;Wolff et al, 2010). Additionally, a correlation with three 40 Ar / 39 Ar dated onshore tephra layers was implemented in the age-depth model of the composite profile, i.e., the Nemrut Formation (NF) at 32.70 ± 2.55 ka BP, the Halepkalesi Pumice (HP-10) fallout at 61.60 ± 2.55 ka BP as well as the Incekaya-Dibekli Tephra at ∼ 80 ka BP (Stockhecke et al, 2014b;Sumita and Schmincke, 2013). Within the last glacial period, the paleomagnetic Laschamp excursion at ∼ 41 ka BP (Vigliotti et al, 2014) could be identified in the core sequence.…”

“…Here we want to stress that, among data sets used for visual correlation, pollen data published in show the glacial-interglacial changes with the largest signal amplitude. However, the age-depth model of Stockhecke et al (2014b) is based on tuning with the NGRIP event stratigraphy. The correlation points of the Lake Van sedimentary record have been mainly defined by abiotic proxies (i.e., TOC) caused by a higher time resolution of this data set in comparison to the pollen samples available during that time.…”