A 350 ka record of climate change from Lake El'gygytgyn, Far East Russian Arctic: refining the pattern of climate modes by means of cluster analysis

Abstract

Rock magnetic, biochemical and inorganic records of the sediment cores PG1351 and Lz1024 from Lake El'gygytgyn, Chukotka peninsula, Far East Russian Arctic, were subject to a hierarchical agglomerative cluster analysis in order to refine and extend the pattern of climate modes as defined by Melles et al. (2007). Cluster analysis of the data obtained from both cores yielded similar results, differentiating clearly between the four climate modes warm, peak warm, cold and dry, and cold and moist. In addition, two transitional phases were identified, representing the early stages of a cold phase and slightly colder conditions during a warm phase. The statistical approach can thus be used to resolve gradual changes in the sedimentary units as an indicator of available oxygen in the hypolimnion in greater detail. Based upon cluster analyses on core Lz1024, the published succession of climate modes in core PG1351, covering the last 250 ka, was modified and extended back to 350 ka. Comparison to the marine oxygen isotope (δ¹⁸O) stack LR04 (Lisiecki and Raymo, 2005) and the summer insolation at 67.5° N, with the extended Lake El'gygytgyn parameter records of magnetic susceptibility (κ_LF), total organic carbon content (TOC) and the chemical index of alteration (CIA; Minyuk et al., 2007), revealed that all stages back to marine isotope stage (MIS) 10 and most of the substages are clearly reflected in the pattern derived from the cluster analysis

A 250 ka oxygen isotope record from diatoms at Lake El'gygytgyn, far east Russian Arctic

“…For a longer time-series, we compared measurements of biogenic silica (BSi [%]), TiO 2 [%] and magnetic susceptibility analysed on the same core (Lz1024; Frank et al, 2012) to our δ 18 O record (Fig. 7).…”

“…The first age model for core Lz1024 was proposed by Juschus et al (2007), using isochronous sediment layers and susceptibility variations to correlate core Lz1024 to the previously dated 13.5 m core PG1351 with the final age model, and then revised after tuning the magnetic susceptibility to the insolation at 70 • N (Nowaczyk et al, 2002. The core base of Lz1024 was dated to a maximum age of 350 ka (Frank et al, 2012; age model for composite profile from ICDP Site 5011-1 in Melles et al, 2012); the focus of this study is on the record of the first 250 ka.…”

GEOMAGIA50.v3: 2. A new paleomagnetic database for lake and marine sediments

“…For example, variations in magnetic susceptibility have been observed to correlate with variations in δ 18 O (e.g., Frank et al 2013;Thouveny et al 1994). Other magnetic parameters, such as the S-ratio (Bloemendal et al 1992;Thompson and Oldfield 1986), have been demonstrated to be sensitive indicators of climate change (e.g., Meynadier et al 1995;Snowball 1993).…”

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)

“…In addition to the vast number of studies on magnetic minerals in marine sediments, lake sediments can provide valuable information on terrestrial and lacustrine environmental conditions (e.g., Frank et al, 2002;Nowaczyk et al, 2002;Peck et al, 1994Peck et al, , 2004Roberts et al, 1996;Snowball, 1993;Snowball et al, 1999;Wang et al, 2008). Depending on the trophic state of the lake, water depth, and stratification, oxygen supply is often limited and may lead to excessive dissolution of iron oxides (e.g., Demory et al, 2005;Snowball et al, 1999).…”