Chronology of Lake El'gygytgyn sediments – a combined magnetostratigraphic, palaeoclimatic and orbital tuning study based on multi-parameter analyses

Abstract

Abstract.A 318-metre-long sedimentary profile drilled by the International Continental Scientific Drilling Program (ICDP) at Site 5011-1 in Lake El'gygytgyn, Far East Russian Arctic, has been analysed for its sedimentologic response to global climate modes by chronostratigraphic methods. The 12 km wide lake is sited off-centre in an 18 km large crater that was created by the impact of a meteorite 3.58 Ma ago. Since then sediments have been continuously deposited. For establishing their chronology, major reversals of the earth's magnetic field provided initial tie points for the age model, confirming that the impact occurred in the earliest geomagnetic Gauss chron. Various stratigraphic parameters, reflecting redox conditions at the lake floor and climatic conditions in the catchment were tuned synchronously to Northern Hemisphere insolation variations and the marine oxygen isotope stack, respectively. Thus, a robust age model comprising more than 600 tie points could be defined. It could be shown that deposition of sediments in Lake El'gygytgyn occurred in concert with global climatic cycles. The upper ∼ 160 m of sediments represent the past 3.3 Ma, equivalent to sedimentation rates of 4 to 5 cm ka −1 , whereas the lower 160 m represent just the first 0.3 Ma after the impact, equivalent to sedimentation rates in the order of 45 cm ka −1 . This study also provides orbitally tuned ages for a total of 8 tephras deposited in Lake El'gygytgyn.

Late Pliocene and Early Pleistocene vegetation history of northeastern Russian Arctic inferred from the Lake El'gygytgyn pollen record

“…The upper boundary of the warm interval coincides rather well with the paleomagnetic Gauss-Matuyama boundary (Melles et al, 2011(Melles et al, , 2012Haltia and Nowaczyk, 2014;Nowaczyk et al, 2013). Thus, vegetation changes showing a transition from interglacial environmental conditions to glacial ones are reflected rather well at the PliocenePleistocene (MIS 104/MIS 103) boundary.…”

“…(2004) stipulated a total of about 600 tie points for the final age model. Further details can be found in Nowaczyk et al (2013).…”

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

“…Its sediments consist of lacustrine carbonates (mostly calcite), biogenic silica, and lithogenic compounds . Lake Ohrid is an oligotrophic lake; a complete overturn and deep mixing occur only every few years, while the upper 200 m of the water column is mixed every year during winter (e.g., Matzinger et al, 2007). Temperature variations probably had a strong influence on shallow and deep mixing of Lake Ohrid during past glacials and interglacials (Vogel et al, 2010a;Wagner et al, 2009); however, to date there is no quantitative estimate of this effect.…”

“…Ohrid is an oligotrophic lake with maximum productivity during summer (Matzinger et al, 2007;Wagner et al, 2010). However, at present, it shows indications for the onset of eutrophication (e.g., Matzinger et al, 2007).…”

“…Magnetic extracts were prepared following the protocol of Nowaczyk (2011). A total of 2 cm 3 of sediment was dispersed in 60 mL of alcohol and Na solution was added.…”