Universität Potsdam Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft Late Quaternary environmental dynamics at the Duvanny Yar key section, Lower Kolyma, East Siberia Diplomarbeit zur Erlangung des akademischen Grades Diplom-Geoökologe vorgelegt von Jens Strauß aus Lünen geboren am 08. Dezember 1984 Universität Potsdam Institut für Erd- und Umweltwissenschaften Potsdam, im Februar 2010 1. Gutachter Dr. Lutz Schirrmeister Alfred-Wegener-Institut für Polar- und Meeresforschung, Telegrafenberg A43, 14473 Potsdam 2. Gutachter Prof. Dr. Hans-Wolfgang Hubberten Alfred-Wegener-Institut für Polar- und Meeresforschung, Telegrafenberg A43, 14473 Potsdam; Gemeinsam berufen mit dem Institut für Erd- und Umweltwissen- schaften, Universität Potsdam, Lehrstuhl Terrestrische Geowissen- schaften Für Jan, Regina und Martin „Die Neugier steht immer an erster Stelle eines Problems, das gelöst werden will.“ Galileo Galilei Contents I Contents Contents .................................................................................................................................................. I List of figures....................................................................................................................................... III List of tables...........................................................................................................................................V Abbreviations and nomenclature....................................................................................................... VI Abstract...............................................................................................................................................VII Kurzfassung...................................................................................................................................... VIII 1 Introduction........................................................................................................................................1 1.1 Scientific relevance and background .............................................................................................1 1.2 Aims ........................................................................................................................................2 2 Geological and geographical background .........................................................................................4 2.1 The periglacial environment..........................................................................................................4 2.1.1 Permafrost .......................................................................................................................4 2.1.2 Ground ice.......................................................................................................................5 2.1.3 Polygonal nets and lakes ................................................................................................7 2.1.4 Thermokarst and alas .......................................................................................................7 2.1.5 Yedoma and Ice Complex................................................................................................8 2.2 Regional setting..........................................................................................................................10 2.2.1 Geological and geographical setting...............................................................................10 2.2.2 Climate, vegetation and soils..........................................................................................11 2.3 The Duvanny Yar section ...........................................................................................................12 3 Methods ............................................................................................................................................15 3.1 General study scheme .................................................................................................................15 3.2 Field work ..................................................................................................................................15 3.2.1 Sediments studies and sampling .....................................................................................16 3.2.2 Studies and sampling of ground ice and recent waters.....................................................16 3.3 Sedimentological analysis...........................................................................................................17 3.3.1 Mass specific magnetic susceptibility .............................................................................17 3.3.2 Grain size analysis .........................................................................................................17 3.3.3 Determination of TC, TOC and TN values .....................................................................19 3.3.4 Bulk density and organic carbon ratio.............................................................................20 3.4 Geochronology...........................................................................................................................21 3.5 Stable isotope geochemistry........................................................................................................22 3.5.1 Carbon isotopes (δ13C) ...................................................................................................22 3.5.2 Oxygen & hydrogen isotopes (δ18O, δ2H).......................................................................24 Contents II 3.6 Hydrochemistry..........................................................................................................................27 3.6.1 Alkalinity measurements................................................................................................27 3.6.2 Determination of anion concentration.............................................................................28 3.6.3 Determination of cation concentration............................................................................29 4 Results...............................................................................................................................................30 4.1 General composition of the Duvanny Yar section........................................................................30 4.2 Lake deposits below/next to the Ice Complex sequence...............................................................30 4.2.1 Profile DY-02................................................................................................................30 4.2.2 Profile DY-03................................................................................................................34 4.2.3 Profile DY-06................................................................................................................37 4.3 Ice Complex ...............................................................................................................................39 4.3.1 Profile DY-05................................................................................................................39 4.3.2 Profile DY-01................................................................................................................45 4.4 Alas deposits ..............................................................................................................................51 4.5 Specific studies on Ice Complex and alas deposits.......................................................................55 4.5.1 Peak fitting at the Ice Complex grain size distributions...................................................55 4.5.2 Bulk density and organic carbon content for Ice Complex and alas deposits....................57 4.6 Hydrochemistry..........................................................................................................................58 5 Discussion .........................................................................................................................................61 5.1 General geomorphology............................................................................................................61 5.2 Geochronological and stratigraphical interpretation .................................................................61 5.3 Sediment facies discussion..........................................................................................................63 5.3.1 Lake deposits................................................................................................................63 5.3.2 Ice Complex..................................................................................................................66 5.3.3 Alas...............................................................................................................................72 5.4 Organic carbon content calculation...........................................................................................73 5.5 Climatic information from ground ice .........................................................................................74 5.5.1 Ice wedges ....................................................................................................................74 5.5.2 Fissure ice and texture ice ............................................................................................76 5.5.3 Summarised paleoclimate interpretation ......................................................................79