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

Reconstruction of cryogenic processes in peat deposit

• f the southern taiga
• f Western Siberia

Preis Preis Yu.I Yu.I . .

n n I nstitute of Monitoring of Climate and

I nstitute of Monitoring of Climate and 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 search, definition of character and genesis of infringements of autogenic autogenic mire formation by mire formation by abiotic abiotic factors and on a complex of indicators of influence factors and on a complex of indicators of influence

• f cryogenic processes on dynamics,
• f cryogenic processes on dynamics, stratigraphy

stratigraphy and properties of peat of and properties of peat of mires of a permafrost zone and on assumption, that similar infri mires of a permafrost zone and on assumption, that similar infringements ngements during the dry cooling periods of the Holocene on mires of outsi during the dry cooling periods of the Holocene on mires of outside of a 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, data of vegetation, stratigraphy stratigraphy and dynamics of mires of permafrost zone and dynamics of mires of permafrost zone

• f Western Siberia (
• f Western Siberia (P

P’ ’yavchenko yavchenko, 1955; , 1955; Tirtikov Tirtikov, 1974; , 1974; Kashperyuk Kashperyuk, , Trofimov Trofimov, 1988; , 1988; Vasil Vasil’ ’chuk chuk, 1986; , 1986; Vasil Vasil’ ’chuk chuk et all, 2008), relic et all, 2008), relic palsa palsa of

• f

southern part of these regions (Baryshnikov, 1929; southern part of these regions (Baryshnikov, 1929; Blyakharchuk Blyakharchuk, 1969; , 1969; Dyukarev Dyukarev, 2005) and our researches of , 2005) and our researches of palsa palsa and and aapa aapa-

• mire of permafrost

mire of permafrost zone of Middle Siberia ( zone of Middle Siberia (Preis Preis, 1991; 2002). , 1991; 2002).

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,

• sition,

ash content, composition and contents of elements, moisture, den ash content, composition and contents of elements, moisture, density, sity, contents of plant pigments, rate of accumulation) to conditions contents of plant pigments, rate of accumulation) to conditions of peat

• f 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 This method allows to reconstruction following kinds of paleocryogenetic paleocryogenetic 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

• f palsa

palsa; ;

• thermokarst

thermokarst of

• f pingo

pingo; ;

• thermoerosion

thermoerosion of

• f 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 n Reconstruction cryogenic processes in

Reconstruction cryogenic processes in peat deposit has been executed on the peat deposit has been executed on the basis of the given basis of the given multiproxy multiproxy detailed detailed studied and studied and 14

14C

C-

• ,

, 210

210Pb

Pb-

• and

and 137

137Cs

Cs-

• datind

datind 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 received by the author during 2003-

• 2007

2007 and and 14

14C

C-

• dating peat sections, containing in

dating peat sections, containing in references. references.

Kind of cryogenic process Kind of cryogenic process – – Formation (1) and d Formation (1) and degradation (2)

egradation (2) permafrost or long thawing seasonal frosted water permafrost or long thawing seasonal frosted water-

• proof in soil

proof in soil

Infringement Infringement -

• discrepancy type

discrepancy type

• f
• f paludification

paludification and soil and soil geochemistry geochemistry Indicator Indicator -

• transitional or raised

transitional or raised type of bottom peat on type of bottom peat on carbonat carbonat soil soil Infringement Infringement -

• depaludification

depaludification a a dried dried elements elements meso meso-

• and

and microrelief microrelief of mineral bottom

• f mineral bottom

Indicators: Indicators: – – significant distinctions of age of significant distinctions of age of the next peat the next peat layers; layers; – – 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.

(1) (1)

(2) (2) Bog Bog “ “Iksinskoe Iksinskoe” ” Bottom soil Bottom soil – – carbonat carbonat loam loam

Kind of cryogenic process Kind of cryogenic process – – D Degradation permafrost or long

egradation permafrost or long thawing seasonal frosted water thawing seasonal frosted water-

• proof in soil

proof in soil

I nfringement I nfringement -

• r

return on

eturn on more more minerotrophic minerotrophic stage of stage of development development

I ndicators I ndicators: :

• inversion

inversion stratigraphy stratigraphy of

• f

peat deposit without peat deposit without inversions of properties of inversions of properties of peat: ash content, peat: ash content, рН

рН,

, contents of ground water contents of ground water elements elements

Formation permafrost or Formation permafrost or long thawing

long thawing seasonaly seasonaly frosted water frosted water-

• proof in

proof in soil soil during cooling ca. 7200; 5100

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

Volkova,1977 Blakharchuk, Klimanov, 1977

1 1

I nfringement I nfringement-

• sharp drying

sharp drying surfaces with formation of surfaces with formation of mesotrophic mesotrophic pine pine-

• shrub

shrub ( (Betula Betula nana) nana)-

• dwarf shrub

dwarf shrub-

• cottongrass

cottongrass communities communities,

,

I ndicators: I ndicators:

• layers transitional shrub

layers transitional shrub-

• dwarf shrub

dwarf shrub-

• cottongrass

cottongrass peat peat I nfringement I nfringement -

• stopping of peat

accumulation I ndicators: I ndicators:

• sharp decreased

sharp decreased peat grow and peat accumulation rate,

• increased content of ash,

increased content of ash, lithophylic lithophylic elements (SC, elements (SC, Th Th) in ) in peat, peat,

• decreased content of ground

decreased content of ground water water elements (Ca, Fe) elements (Ca, Fe)

n n I nfringement

I nfringement -

• redistribution of a moisture

redistribution of a moisture in peat deposit because of its in peat deposit because of its migration toward frozen migration toward frozen front front I ndicators: I ndicators:

• infringement of the

infringement of the coordinated change of index coordinated change of index

• f humidity, humidity (W)
• f humidity, humidity (W)

and degree of decomposition and degree of decomposition (R) of peat in peat deposit, (R) of peat in peat deposit,

• water layer on border a

water layer on border a peat peat – –ground. ground.

Kinds of cryogenic process Kinds of cryogenic process -

• Formation (1) and degradation (2) of

Formation (1) and degradation (2) of palsa palsa

(1) (1) (2) (2)

I nfringement I nfringement – – catastrophic catastrophic transition on transition on oligotrophical

• ligotrophical

development development stage stage I ndicator: I ndicator:

• sharp change of peat botanical

sharp change of peat botanical composition with formation of composition with formation of raised sphagnum peat raised sphagnum peat I nfringement I nfringement – – sharp change of a water sharp change of a water-

• mineral regime type

mineral regime type I ndicator: I ndicator:

• sharp decrease of ach

sharp decrease of ach content, content, рН рН, content of ground , content of ground water elements in peat water elements in peat I nfringement I nfringement – – asceleration asceleration of peat

• f peat

accumulation accumulation I ndicator: I ndicator:

• increase of grow and

increase of grow and peat accumulation rate peat accumulation rate

Formation of Formation of palsa palsa – – ca. 4350 PB; 4100 PB and degradation of

• ca. 4350 PB; 4100 PB and degradation of palsa

palsa ca. 3600 PB

• ca. 3600 PB

Formation of Formation of palsa palsa ca. 3050

• ca. 3050-
• 2900 PB; 2180

2900 PB; 2180-

• 2115 PB; 1370 PB and

2115 PB; 1370 PB and degradation of degradation of palsa palsa ca. 2400 PB; 1900 PB; 1000 PB

• ca. 2400 PB; 1900 PB; 1000 PB

g m

20 40 60 80 1000 2000 3000 4000 year

g m

20 40 60 80 100 120 1000 2000 3000 4000 year

Formation of Formation of palsa palsa ca. 570

• ca. 570-
• 520; 150 PB; actual

520; 150 PB; actual time; time; and degradation of and degradation of palsa palsa

• ca. 275
• ca. 275-
• 250 PB; 100 PB

250 PB; 100 PB

I nfringement I nfringement – – transition to transition to subaeral subaeral conditions, conditions, died hygrophytes died hygrophytes plant plant communites communites, , formation of formation of mesopsychrophytes mesopsychrophytes dwarf shrub dwarf shrub-

• mosses

mosses-

• lichens or

lichens or Pinus Pinus sibirica sibirica-

• green

green mosses ( mosses ( bryum bryum) ) communities communities I ndicator: I ndicator: -

• a peat

a peat layer with remains layer with remains

• f
• f ericaceae

ericaceae, , Pleurozium Pleurozium schreberi schreberi, , Hylacomium Hylacomium splendens splendens, , Polytrichum Polytrichum strictum strictum), ),

• a forest

a forest floorl floorl layer layer from the remains of from the remains of a bark and wood of a bark and wood of a cedar, forest a cedar, forest mosses mosses I nfringement I nfringement -

• stopping of peat

accumulation I ndicators: I ndicators:

• sharp decreased

sharp decreased peat grow and peat accumulation rate,

• increased content of

increased content of ash ash

Thanks for attention! Thanks for attention!