Results of research into Holocene sediments of the South and Central basins of Lake Baikal (BDP-97 and short cores)

Abstract

Results of investigations of Baikal bottom sediments from a long core (BDP-97) and several short (0–1 m) cores are presented. It has been shown that the Holocene sediments in the Baikal basins consist of biogenic-terrigenous muds, accumulated under calm sedimentation conditions, and of turbidites, formed during catastrophic events. The turbidites can be distinguished from the host sediments by their enrichment in heavy minerals and thus their high magnetic susceptibility. Often, Pliocene and Pleistocene diatom species observed in the Holocene sediments (mainly in the turbidites) point to redeposition of ancient offshore sediments. Our results indicate that deltas, littoral zones, and continental slopes are the source areas of turbidites. The fact that the turbidites occur far from their sources confirms the existence of high-energy turbidity currents responsible for long-distance lateral-sediment transport to the deep basin planes of the lake.

Fingerprinting historical fluvial sediment fluxes

“…Mineralogical tracers have been widely applied, and different mineral groups can be used. Whereas some studies take into account the bulk mineralogical composition of the sediments (Abu-Zeid et al, 2001;Arribas et al, 2000;Benedetti et al, 2006), others have focussed on clay minerals (Eberl, 2004;Gingele and De Deckker, 2005) or the heavy mineral content (Basu and Molinaroli, 1991;Damiani and Giorgetti, 2008;Dill, 1998;Dinis and Soares, 2007;Ergin et al, 2007;Hounslow and Morton, 2004;Morton and Hallsworth, 1999;Oszczypko and Salata, 2005;Sabeen et al, 2002;Vezzoli et al, 2004;Vologina et al, 2007;von Eynatten and Gaupp, 1999). The choice of an appropriate method is obviously dependent on the grain-size distribution of the sediment.…”

“…These potential sources are usually themselves older sediments with, for example, a distinct set of pollen or spores (Brown, 1985). In lacustrine and coastal settings the occurrence of ancient species of, respectively, diatoms (Vologina et al, 2007) or foraminifera (Haslett et al, 2000) can indicate the reworking of older sediments.…”

Microbial Communities in Ferromanganese Sediments from the Northern Basin of Lake Baikal (Russia)

“…The authors of these manuscripts suggested that these taxa could be the markers of climate change; in particular, Firmicutes mark synergetic freezing of sediments (hypothesis of a marker of syngenetic sediment formation) [98]. Most likely, the unusually high contribution of Firmicutes, with a decrease in Chloroflexota, in the investigated St7Grf6 core could be due to the influence of turbidites that were common in the sediments of the northern basin of Lake Baikal and that could had been formed during the advance and retreat of glaciers in the Late Pleistocene [99,100]. The influence of ice rafting cannot also be excluded, the traces of which were often identified in the sediments of this area [101].…”

Holocene and Late Glacial sedimentation near steep slopes in southern Lake Baikal

“…The turbidites contain diatoms, which are characteristic for Pliocene/Pleistocene. These diatoms do not appear within the normally deposited pelagic muds but are common in deep-water turbidites of other sites (Vologina et al, 2007). Their sources are Pliocene/Pleistocene sediments, which are widespread along the South-and SE-coast of Southern Baikal and are not exposed at the North coast of this basin (Mats, 1985;Imetkhenov, 1987;Atlas of Baikal, 1993;Mats et al, 2001).…”