Dynamics of the Regional Climatic Conditions over the Past 2000 Years on the Basis of Lithogeochemical Analysis of the Bottom Sediments of Lake Karakyol (Western Caucasus)

Abstract

Reference section of the bottom sediments of Lake Karakyol (Caucasus) is built based on the cores obtained during the 2010 and 2014 field works, taking into account radiocarbon dating and the data of analytical microstratigraphy. Using the methods of scanning micro-XRF, solid preparations of bottom sediments were scanned in 1 mm increments with simultaneous determination of the content of more than 25 rock-forming and microelements. When building the master-core, the profiles of changes in the content of terrigenous elements were taken into account. This made it possible to precisely combine the two cores and remove from the section the sediment intervals corresponding to the “one-time” events – terrigenous material injections. Comparison of instrumental data of regional meteorological observations in the period 1927–2010 with the time series of geochemical indicators showed the presence of a stable relationship of the composition of bottom sediments with the average 11-year temperatures. Approximation of transfer functions to the depth of core testing allowed constructing a paleoclimatic reconstruction of regional temperature for the last 2 millennia with a time resolution of 5–10 years.