Climatic forcing on varve sedimentation regimes through the Holocene from Lake Nautajärvi, Southern Finland. 

• DOI: 10.5194/egusphere-egu24-11092
• Publication Date: 2024-03-08T20:55:33Z
• Authors: Paul Lincoln; Rik Tjallingii; Emilia Kosonen; Antti Ojala; Celia Martin-Puertas
• Keywords: Varve; Sedimentation; Forcing (mathematics)

During the Holocene, European high latitudes experienced substantial alterations in temperature and precipitation patterns. These changes were driven by a complex combination of factors, including impacts orbital solar forcing on insolation, dynamics ocean-atmospheric circulation regimes, various related feedback mechanisms. Sedimentation regimes Boreal lakes can be sensitive to these climate thus provide valuable archive better understand climatic processes. Limitations sampling resolution, chronological precision, proxy sensitivity however have traditionally made continuous proxy-based palaeoclimatic reconstructions difficult achieve through particularly prior instrumental period (c. <1800 AD). Annually laminated lacustrine or varved sediments offer significant potential improve our understanding sub-millennial sub-decadal mechanisms regions such as northern latitudes.  Here we present XRF core scanning records new sedimentary sequence from dimictic Lake Nautajärvi, Southern Finland, which is continuously for last 10 ka. Statistical exploration data clearly distinguishes elements associated with detrital material (Ti, K, Si), redox conditions (Fe, Mn) organic content ((ln(inc/coh)). Consequently, will show how signals used proxies different seasonal sedimentation lake, winter catchment snow accumulation, lake stratification induced benthic redox, biogenic productivity during growing season. Spectral analysis reveals statistically non-stationary decadal multicentennial cyclicity processes align known Gleissberg Suess cycles periodic variability North Atlantic atmospheric regimes. Changes frequencies throughout demonstrates that dominant external affected The clearest shift occurs mid-Holocene, between 6 5 ka BP, when switches predominantly solar-cycle forced decadal-centennial scale influx productivity. shifts correspond <5 BP trends observed other records, indicating increased patterns mid-Holocene. Such findings highlight clastic-biogenic tracing Europe.