Fossil carbon – origin, properties and dynamic

WP 2 explores the stratigraphic structure of the permafrost sequences. The focus lies on the vertical and lateral distributions of fossil carbon as well as the paleo-environmental conditions during the accumulation of fossil organic matter. The spatial and temporal differentiation of the investigated permafrost deposits creates the geoscientific context for the interpretation of the Quaternary environmental conditions. In this sense, WP 2 provides important prerequisites for the interpretation of data from WP 3 and WP 5 and is included in the modeling in WP 6.

Networking scheme of work package 2

Objectives

  • Formation, degradation and transformation of fossil organic matter during Quaternary climate changes
  • Vertical (stratigraphy) and lateral (paleogeography) distribution of fossil organic matter in permafrost sequences
  • Spatial and temporal differentiation using cryolithological, geophysical, paleoecological, and geochronological methods

Study site

The research of WP 2 is focuses on the south coast of Bol’shoy Lyakhovsky Island (New Siberian Archipelago) where the longest (pre Eemian to Holocene) and one of the best-studied permafrost sequences are exposed. In addition, a Yedoma core from the Buor Khaya Peninsula (drilled in 2012) is already in process for cryolithological and fosill bioindicator studies.

The study area of Bol’shoy Lyakhovsky Island with potential drill and study sites

Work Program

Cryolithological characterization of permafrost deposits

  • Which permafrost and sedimentation conditions are indicated for the time of formation or freezing of the each stratigraphic unit?
  • Which stratigraphic units were subject to post-sedimentary processes such as freezing, thawing and re-freezing and by cryogenic deformation?
  • Which geophysical properties identify/characterize the individual stratigraphic units?

Methods: exposure description and sampling, sedimentological analysis (grain size, CNS, δ13C (bulk organic), magnetic susceptibility), cryofacies-analysis (Ice and sediment structures), Ground ice stable isotopes, geophysical imaging.

Yedoma ice wedges and frozen paleosoil sequences in-between at Bol’shoy Lyakhovsky IslandYedoma ice wedges and frozen paleosoil sequences in-between at Bol’shoy Lyakhovsky Island.

Determination of the taxonomic composition of the organic matter (Alfred Wegener Institute, Potsdam)

  • Which plant communities and other fossil remains compose the organic matter in different stratigraphic units?
  • What are the modern analogues of the former plant communities?
  • How fossil and modern organisms differ in their elemental and isotopic composition?
  • What conclusions can be drawn for organic matter degradation processes?
  • What local paleoenvironmental conditions are indicated by the organism communities (e.g. temperature, precipitation, water depth and chemistry and soil)?

Methods: Pollen and spore analysis, plant macro fossil analysis, Study of diatoms, cladocera, tecamoebae and other available fossil bioindicators, Identification of fossil  DNA from sediments, species-specific biogeochemical analysis (TC, TIC-, TOC-, TN, TS concentration, C/N ratios, C- and N- isotopes), studies of modern bioindicator analogues.

Fossil bioindicators of paleo-environmental archive permafrost (clockw.: shells of soil amoebae, mammal teeth, plant seeds, pollen, beetle remains, ostracods shells)

Structure, spatial extent and geochronological classification of stratigraphic units (Alfred Wegener Institute, Potsdam)

  • Which landscape conditions favor organic matter formation and accumulation?
  • Which geochronological methods prove to be particularly reliable for age modeling?
    • Radiocarbon AMS dating of identified fossil remains, up to ca. 50 ka (WP3)
    • Luminescence dating up to 150 ka, (Luminescence Laboratory, TU Bergakademie Freiberg, Institute of Applied Physics)
    • U/Th dating of frozen peat up to ca. 500 ka (Leibniz Institute for Applied Geophysics Hannover; St. Petersburg State University, Laboratory of Geochronology and Geoecology)
  • How do sediment parameters and cryogenic properties influence geochronological results?
  • What are potentials and limitations of luminescence methods applied to permafrost sediments?
    • Signal characteristics (sensitivity, stability, dating limits) for quartz and feldspar analyses
    • Statistical age modeling (bleaching, sediment mixing)
    • Material analytics including sediment dosimetry (variability, radioactive disequilibria, water and ice content) and ice pressure (grain size effects, signal stability)

Geophysical studies of permafrost deposits (Institute of Earth and Environmental Science, Applied Geophysics, Potsdam University)

  • What is the internal structure, the spatial arrangement and variability of stratigraphic units in the permafrost sequences?
  • Mapping the stratification of the frozen ground by means of 2D/3D ground penetrating radar (GPR), Electrical Resistivity Tomography (ERT), and Electromagnetic induction (EMI)

German applicants

Dr. Lutz Schirrmeister and Prof. Dr. Ulrike Herzschuh, Alfred Wegener Institute, Potsdam

Prof. Dr. Jens Tronicke, University Potsdam, Institute of Earth and Environmental Science

Prof. Dr. Johannes Heitmann, Technical University Freiberg, Institute of Applied Physics

Russian partners

Dr. M. N. Grigoriev, Permafrost Institute Jakutsk, RAS SB

Prof. A. Bobrov, Moscow State University, Faculty of Soil Science

Prof. Dr. L. Pestryakova, Northeast Federal University Yakutsk, Biological-Geographical Faculty

Dr. V. Tumskoy, Moscow State University, Geological Faculty

Project employees

Margret Fuchs – Scientist, geochronology

Stephan  Schennen – PhD student, geophysics

Heike Zimmermann – PhD student, paleoecology

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News

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