Reconstruction of cryogenic processes in peat deposit of the - PowerPoint PPT Presentation

Reconstruction of cryogenic processes in peat deposit of the southern taiga of Western Siberia Preis Yu.I Yu.I . . Preis n I nstitute of Monitoring of Climate and I nstitute of Monitoring of Climate and n Ecological Systems SB RAS, Tomsk, Russia Ecological Systems SB RAS, Tomsk, Russia

n Mires are the main landscapes of Western Siberia. Therefore definition of tendencies of their development in the future is extremely important. n In Western Siberia relic palsa meets within all area of forest zone, but their age, stratigraphy and scales of distribution during the cooling periods of the Holocene outside of a permafrost zone practically are not studied. n Qualitative forecasts of cryogenic processes is possible only on the basis of dates of their revealing in the past. n Traces of permafrost were not kept in thawed bogs. The reconstruction of cryogenic processes in peat deposit of thawed bogs is absent.

In the given report the new method of search and definition of character of cryogenic processes in peat deposit and results of application of the given method at bogs of southern taiga subzone of Western Siberia. This method has basis on system This method has basis on system- -evolutionary methodical approach of evolutionary methodical approach of search, definition of character and genesis of infringements of autogenic search, definition of character and genesis of infringements of autogenic mire formation by abiotic mire formation by abiotic factors and on a complex of indicators of influence factors and on a complex of indicators of influence of cryogenic processes on dynamics, stratigraphy of cryogenic processes on dynamics, stratigraphy and properties of peat of and properties of peat of mires of a permafrost zone and on assumption, that similar infringements mires of a permafrost zone and on assumption, that similar infri ngements during the dry cooling periods of the Holocene on mires of outside of a during the dry cooling periods of the Holocene on mires of outsi de of a permafrost zone also have cryogenic genesis. permafrost zone also have cryogenic genesis. The complex of indicators is revealed on the basis of the analys The complex of indicators is revealed on the basis of the analysis of is of data of vegetation, stratigraphy data of vegetation, stratigraphy and dynamics of mires of permafrost zone and dynamics of mires of permafrost zone of Western Siberia (P of Western Siberia ( P’ ’yavchenko yavchenko, 1955; , 1955; Tirtikov Tirtikov, 1974; , 1974; Kashperyuk Kashperyuk, , Trofimov, 1988; Trofimov , 1988; Vasil Vasil’ ’chuk chuk, 1986; , 1986; Vasil Vasil’ ’chuk chuk et all, 2008), relic et all, 2008), relic palsa palsa of of southern part of these regions (Baryshnikov, 1929; Blyakharchuk southern part of these regions (Baryshnikov, 1929; Blyakharchuk, 1969; , 1969; Dyukarev, 2005) and our researches of Dyukarev , 2005) and our researches of palsa palsa and and aapa aapa- -mire of permafrost mire of permafrost zone of Middle Siberia (Preis Preis, 1991; 2002). , 1991; 2002). zone of Middle Siberia (

At revealing infringements are considered: At revealing infringements are considered: - species compositions and character successions of plant communi species compositions and character successions of plant communities, ties, - - completeness and sequence of stages of a water - completeness and sequence of stages of a water- -mineral regime, mineral regime, - conformity of parameters of peat properties (a degree of decomp conformity of parameters of peat properties (a degree of decomposition, osition, - ash content, composition and contents of elements, moisture, density, sity, ash content, composition and contents of elements, moisture, den contents of plant pigments, rate of accumulation) to conditions of peat contents of plant pigments, rate of accumulation) to conditions of peat formation, formation, - a coordination of changes of these parameters on peat deposit d - a coordination of changes of these parameters on peat deposit depth, epth, - depth of genetically homogeneous or of one depth of genetically homogeneous or of one- -age layers of peat, age layers of peat, - - number, specific composition of test amoebas and number, specific composition of test amoebas and diatomeae diatomeae, integrity of , integrity of - their shell at all. their shell at all. This method allows to reconstruction following kinds of paleocryogenetic paleocryogenetic This method allows to reconstruction following kinds of processes: processes: - formation and degradation of permafrost water - formation and degradation of permafrost water- -proof in soil; proof in soil; - formation and degradation of permafrost water formation and degradation of permafrost water- -proof in peat deposit, proof in peat deposit, - - formation and formation and thermokarst thermokarst of of palsa palsa; ; - - thermokarst - thermokarst of of pingo pingo; ; - thermoerosion thermoerosion of of palsa palsa and of mineral ground and of mineral ground permafrost of surrounding permafrost of surrounding - waterless valleys; waterless valleys; - peat shrinkage under thawing permafrost. peat shrinkage under thawing permafrost. -

n Reconstruction cryogenic processes in Reconstruction cryogenic processes in n peat deposit has been executed on the peat deposit has been executed on the basis of the given multiproxy multiproxy detailed detailed basis of the given 14 C 210 Pb 137 Cs studied and 14 , 210 and 137 C- -, Pb- - and Cs- -datind datind studied and peat sections of 73 key areas of mires of peat sections of 73 key areas of mires of southern taiga of Western Siberia, southern taiga of Western Siberia, received by the author during 2003- -2007 2007 received by the author during 2003 14 C and 14 C- -dating peat sections, containing in dating peat sections, containing in and references. references.

Kind of cryogenic process – Kind of cryogenic process – Formation (1) and d Formation (1) and d egradation (2) egradation (2) permafrost or long thawing seasonal frosted water- -proof in soil proof in soil permafrost or long thawing seasonal frosted water (1) (1) Infringement - Infringement - discrepancy type discrepancy type of paludification paludification and soil and soil of geochemistry geochemistry Indicator - Indicator - transitional or raised transitional or raised type of bottom peat on carbonat carbonat type of bottom peat on soil soil (2) (2) Infringement - - depaludification depaludification a a Infringement dried elements dried elements meso meso- - and and microrelief of mineral bottom of mineral bottom microrelief Indicators: Indicators: – significant distinctions of age of – significant distinctions of age of the next peat layers; layers; the next peat – stopping of peat accumulation; – stopping of peat accumulation; – increase of a degree of increase of a degree of – decomposition (R) and bulk decomposition (R) and bulk density (P) of bottom peat in density (P) of bottom peat in result of secondary result of secondary decomposition. decomposition. Bog “ Bog “Iksinskoe Iksinskoe” ” Bottom soil Bottom soil – – carbonat carbonat loam loam

Kind of cryogenic process – – D D egradation permafrost or long Kind of cryogenic process egradation permafrost or long thawing seasonal frosted water- -proof in soil proof in soil thawing seasonal frosted water I nfringement - I nfringement - r r eturn on eturn on more more minerotrophic minerotrophic stage of stage of development development I ndicators I ndicators: : - inversion - inversion stratigraphy stratigraphy of of peat deposit without peat deposit without inversions of properties of inversions of properties of рН , peat: ash content, рН , peat: ash content, contents of ground water contents of ground water elements elements

long thawing seasonaly seasonaly frosted water frosted water- -proof in proof in Formation permafrost or long thawing Formation permafrost or soil during cooling ca. 7200; 5100 soil during cooling ca. 7200; 5100- -4800; 3900 4800; 3900- -3700 PB and degradation this 3700 PB and degradation this water water- -proof in soil during subsequent warming and ca 2600 proof in soil during subsequent warming and ca 2600- -2500 PB 2500 PB Blakharchuk, Volkova,1977 Klimanov, 1977