3 research outputs found
Holocene oxygen isotope record of diatoms from Lake Kotokel (southern Siberia, Russia) and its palaeoclimatic implications
The oxygen isotope composition of diatom silica (d18Odiatom) from marine and lake sediments is helpful
for the interpretation of the past climate and environments, especially when complemented by other
proxy records. This paper presents a Holocene oxygen isotope record of diatoms from Lake Kotokel,
located 2 km east of Lake Baikal in southern Siberia, Russia. The isotope record displays variations in
d18Odiatom from +23.7 to +30.3‰ from about 11.5 ka BP until today. Comparing the isotope composition
of recent Lake Kotokel water (mean d18O = -12‰) to that of the most recent diatom sample
(d18O = +27.5‰), an isotope fractionation in the right order of magnitude was calculated. The Kotokel
d18O diatom record is rather controlled by changes in the isotopic composition of the lake water rather
than by lake temperature. Lake Kotokel is a dynamic system triggered by differential environmental
changes closely linked with various lake-internal hydrological factors. A continuous depletion in d18O of
6.6‰ is observed from Early to Late Holocene, which is in line with other hemispheric environmental
changes (i.e. a Mid- to Late Holocene cooling). Enhanced evaporation effects and higher relative supply
from a southerly moisture source explain the relatively heavy isotopic composition in a rather cold Early
Holocene. In summary, changes in the Holocene d18O diatom record of Lake Kotokel reflect variations in
d18O of precipitation linked with both Tair as well as evaporation effects and, to a lesser degree, meltwater
pulses from the mountainous hinterland and changing atmospheric moisture sources