Climate changes over the last 13500 years based on lake sediments studies (Lake bolshoe Miassovo, South ural, Russia)

Abstract

© 2019, International Multidisciplinary Scientific Geoconference. All rights received. We performed petromagnetic, elemental composition and mineralogical investigations of samples from lake Bolshoe Miassovo, Chelyabinsk region, Russia (55°9′59.89″N 60°20′51.82″E). Based on seismoacoustic investigation 5 long (up to 5.3 m) cores were collected by special hydraulical core extractor constructed in institute. For core sampling were choosen places with continuous sedimentation and absence of gas diffusion. Samples for laboratory investigations were selected layer by layer in intervals of 2 cm. The principle aim of our study is to study paleoclimate in this region and accumulation conditions of sediments based on magnetic and chemical features of sediments. Petromagnetic studies included the measurement of magnetic susceptibility (MS), natural remanent magnetization (NRM), hysteresis parameters and induced magnetization versus temperature. Elemental composition of sediments measured using the S8 Tiger X-ray fluorescence wave-dispersion spectrometer (Bruker), mineralogy studies carried out on a diffractometer Bruker D2 Phaser. Relation between magnetic parameters, elemental composition, сhemical weathering indices shows strong correlation between them Also according obtained data there is a sharp change of these parameters on depth 4,3 – 4,5 m which corresponds to the 11400-12000 years according radiocarbon dating. Obtained data shows that there are at least two stages of lake evolution; first one – in more humid climate, when there were a lot of incoming material to sedimentation basin and it last till ~11400 years; second stage is warmer and organic material accumulation dominates, this stage continue till the present time. Obtained data in agreement with climate changes data for this region.