Multivariate statistic and time series analyses of grain-size data in quaternary sediments of Lake El'gygytgyn, NE Russia

Abstract

Abstract. Lake El'gygytgyn, located in the Far East Russian Arctic, was formed by a meteorite impact about 3.58 Ma ago. In 2009, the International Continental Scientific Drilling Program (ICDP) at Lake El'gygytgyn obtained a continuous sediment sequence of the lacustrine deposits and the upper part of the impact breccia. Here, we present grain-size data of the past 2.6 Ma. General downcore grain-size variations yield coarser sediments during warm periods and finer ones during cold periods. According to principal component analysis (PCA), the climate-dependent variations in grainsize distributions mainly occur in the coarse silt and very fine silt fraction. During interglacial periods, accumulation of coarser material in the lake center is caused by redistribution of clastic material by a wind-induced current pattern during the ice-free period. Sediment supply to the lake is triggered by the thickness of the active layer in the catchment and the availability of water as a transport medium. During glacial periods, sedimentation at Lake El'gygytgyn is hampered by the occurrence of a perennial ice cover, with sedimentation being restricted to seasonal moats and vertical conduits through the ice. Thus, the summer temperature predominantly triggers transport of coarse material into the lake center. Time series analysis that was carried out to gain insight into the frequency of the grain-size data showed variations predominately on 98.5, 40.6, and 22.9 kyr oscillations, which correspond to Milankovitch's eccentricity, obliquity and precession bands. Variations in the relative power of these three oscillation bands during the Quaternary suggest that sedimentation processes at Lake El'gygytgyn are dominated by environmental variations caused by global glacial-interglacial variations (eccentricity, obliquity), and local insolation forcing and/or latitudinal teleconnections (precession), respectively.

Modern sedimentation processes in Lake Towuti, Indonesia, revealed by the composition of surface sediments

“…The freeze-dried samples were homogenized and split into two aliquots. One aliquot of 1 g was used for grain-size analyses, following a threestep pre-treatment procedure adapted after Francke et al (2013). First, OM was dissolved with 15 ml H 2 O 2 (30%) in a water bath at 50°C for 18 h. This step was repeated once to ensure that the OM was fully dissolved.…”

High‐latitude vegetation and climate changes during the Mid‐Pleistocene Transition inferred from a palynological record from Lake El'gygytgyn, NE Russian Arctic

“…Time‐series analysis on PC1 values of grain‐size data from the same core has shown different results with respect to the relative dominance of orbital cycles (Francke et al . ). According to these data, a 98.5‐ka cycle became initiated about 1250 ka ago.…”

“…Grain‐size changes reflect the duration of lake‐ice cover and thickness of the active layer in summertime (Francke et al . ), while changes in landscape openness point to variations in the regional vegetation cover. Local responses of the lake surface and regional vegetation cover to orbitally controlled climate change might exhibit diverse patterns.…”

“…The differences reflected in the analysis of grain-size and landscape-openness data might be due to different signals of superimposed climate dynamics caught by these two proxies. Grainsize changes reflect the duration of lake-ice cover and thickness of the active layer in summertime (Francke et al 2013), while changes in landscape openness point to variations in the regional vegetation cover. Local responses of the lake surface and regional vegetation cover to orbitally controlled climate change might exhibit diverse patterns.…”

“…High-resolution multi-proxy studies of this core have provided invaluable insights into regional and global climatic response to changes in orbital forcing (e.g. Melles et al 2012;Brigham-Grette et al 2013;Francke et al 2013;Tarasov et al 2013;Andreev et al 2014;Wennrich et al 2014Wennrich et al , 2016. Amongst these studies, palynological analyses provide insights into the vegetation and climate history since the upper Pliocene (Lozhkin et al 2007;Andreev et al 2012Andreev et al , 2014Andreev et al , 2016Tarasov et al 2013;Zhao et al 2015).…”