The Use of Biomarker and Stable Isotope Analyses in Palaeopedology Reconstruction of Middle and Late Quaternary Environmental and Climate History, with Examples from Mt. Kilimanjaro, NE Siberia and NE Argentina Dissertation zur Erlangung des Grades Doktor der Naturwissenschaften (Dr. rer. nat.) an der Fakultät Biologie/Chemie/Geowissenschaften der Universität Bayreuth vorgelegt von Michael Zech geb. am 13.05.1977 in Rosenheim Bayreuth, Oktober 2006 Vollständiger Abdruck der von der Fakultät für Chemie, Biologie und Geowissenschaften der Universität Bayreuth genehmigten Dissertation zur Erlangung des Grades eines Doktors der Naturwissenschaften (Dr. rer. nat.). Die Arbeiten zur vorliegenden Dissertation wurden im Zeitraum von Juni 2003 bis Oktober 2006 am Lehrstühl Geomorphologie (unter Leitung von Prof. Dr. L. Zöller) und an der Abteilungen für Bodenphysik (unter Betreuung von PD Dr. B. Glaser) der Universität Bayreuth durchgeführt. Einreichung der Dissertation: 10. Oktober 2006 Tag des wissenschaftlichen Kolloquims: 29. Januar 2007 Erstgutachter: Prof. Dr. L. Zöller Zweitgutachter: PD Dr. B. Glaser Prüfungsausschuss: Prof. Dr. G. Gebauer (Vorsitz) Prof. Dr. L. Zöller PD Dr. B. Glaser Prof. Dr. Y. Kuzyakov Prof. Dr. E. Matzner Kontakt/communications: [email protected] Verfügbar als PDF unter/available as PDF at: http://opus.up.uni-bayreuth.de Dedicated to my friends in need I Contents Contents I List of Tables VI List of Figures VII List of Abbreviations XII Summary………………………………………………………………………………...…XIV Zusammenfassung………………………………………………………………………..XVII I. Extended Summary 1. Introduction……………………………………………………………………………….2 1.1 Rationale 2 1.2 Biomarkers in palaeopedology 2 1.3 Stable carbon and nitrogen isotopes in palaeopedology 3 1.4 Objectives 4 2. Study Areas……………………………………...………………………………….….…5 2.1 Mt. Kilimanjaro, Equatorial East Africa (Study 1) 5 2.2 Forelands of the Verkhoyansk Mountains, Northeast Siberia (Studies 2, 3 and 4) 6 2.3 Misiones, subtropical Northeast Argentina (Studies 5 and 6) 6 3. Analytical Methods…………………………………………………………………….…7 3.1 Biomarker analyses 7 3.2 Stable carbon and nitrogen analyses 8 3.3 Compound-specific isotope analysis 8 4. Results and Discussion………………………………………...…………………………9 4.1 Biomarkers 9 4.1.1 n-Alkanes in the three investigated ecosystems (Studies 1, 4 and 5) 9 4.1.2 Amino acid enantiomers in the Tumara Palaeosol Sequence (Study 2) 13 4.2 Stable isotope results 13 4.2.1 Natural abundance of 13C in the three investigated palaeosol records (Studies 1, 3 and 5) 13 4.2.2 Compound-specific δ13C results (Study 6) 15 4.2.3 Natural abundance of 15N in the the Tumara Palaeosol Sequence (Study 3) 17 II 4.3 Reconstruction of the palaeoenvironmental and climate history of the three ecosystems under study 17 4.3.1 Mt. Kilimanjaro (Study 1) 17 4.3.2 Forelands of the Verkhoyansk Mountains (Studies 2,3 and 4) 18 4.3.3 Misiones, subtropical Northeast Argentina (Studies 5 and 6) 19 5. Conclusions………………………………………………………………………….…...20 6. Contributions to the included manuscripts……………………………………….…...22 References 23 II. Cumulative Study Study 1: Evidence for Late Pleistocene climate changes from buried soils on the southern slopes of Mt. Kilimanjaro, Tanzania Abstract 31 1. Introduction……………………………………………………………………….……..32 2. Materials and Methods……………………………………………………………..…...32 2.1 Study area 32 2.2 Field work and working hypotheses 34 2.3 Sample preparation and laboratory analyses 35 3. Results and Discussion………………………………...………………………………..36 3.1 Elemental analyses 36 3.2 Biomarker and stable carbon isotope analyses 38 3.2.1 Black Carbon (BC) 38 3.2.2 n-Alkanes 38 3.2.3 Stable carbon isotopes 39 3.3 Palaeopedologic reconstruction of the vegetation history and palaeoclimatic implications 40 4. Conclusions……………………………………………………………………….……..43 Acknowledgements 44 References 44 III Study 2: Multi-proxy analytical characterization and palaeoclimatic interpretation of the Tumara Palaeosol Sequence, NE Siberia Abstract 48 1. Introduction……………………………………………………………………………...49 2. Geological Setting and Stratigraphy of the Tumara Palaeosol Sequence ……...…...51 3. Materials and Methods………………………………………………………….....…...53 4. Results and Discussion……………………………………………………………...…..55 4.1 Grain size distribution 55 4.2 Geochemical characterization 59 4.3 Magnetic susceptibility 64 4.4 Characterization of the soil organic matter 65 5. Towards a Chronology for the Tumara Palaeosol Sequence………………….…...…67 6. Conclusions……………………………………………………………………….….…..72 Acknowledgements 74 References 74 Study 3: A 240,000-year stable carbon and nitrogen isotope record from a loess-like palaeosol sequence in the Tumara Valley, Northeast Siberia Abstract 81 1. Introduction……………………………………………………………………………..82 2. Geological Setting, Stratigraphy and Chronology of the Tumara Profile..….....…...83 3. Materials and Methods………………………………………………………………....86 4. Results and Discussion……………………………………………………………...…..87 4.1 Carbon and nitrogen contents 87 4.2 Natural abundance of 13C 89 4.3 Natural abundance of 15N 94 5. Conclusions……………………………………………………………………….….….96 Acknowledgements 96 References 97 IV Study 4: Reconstruction of NE Siberian vegetation history based on cuticular lipid biomarker and pollen analyses Abstract 102 1. Introduction………………………………………………………………………….....103 2. Materials and Methods…………………………………………………………….….104 2.1 Geographical setting 104 2.2 The Tumara Palaeosol Sequence 104 2.3 Alkane and pollen analyses 105 3. Results ……………….……………………………………………………………....…105 3.1 n-Alkane patterns 105 3.2 Pollen diagram 108 4. Discussion………………….…...............................................................................……110 4.1 Comparison of alkane and pollen results 110 4.2 Palaeoclimatic interpretation of the alkane and pollen results 111 4.3 Palaeovegetation versus pedogenic/glacial history 112 5. Conclusions………………………………………………………………………….…113 Acknowledgements 114 References 114 Study 5: Late Quaternary environmental changes in Misiones, subtropical NE Argentina, deduced from multi-proxy geochemical analyses in a palaeosol-sediment sequence Abstract 118 1. Introduction…………………………………………………………………………....119 2. Regional Setting and modern Climate……………………………….…………...….120 3. Materials and Methods…………………………………………………………….….121 4. Results and Discussion………………………………………………………...…....…124 4.1 Chronostratigraphy 124 4.2 Characterization of the organic matter 127 4.3 Lacustrine biomarkers 131 4.4 n-Alkane ratio nC31/nC27 as proxy for the palaeovegetation 131 V 5. Synthesis: Late Quaternary palaeoenvironmental and palaeoclimate evolution.....133 6. Conclusions……………………………………………………………………….……138 Acknowledgements 139 References 139 Study 6: Improved compound-specific δ13C analysis of n-alkanes for the application in palaeoenvironmental studies Abstract 146 1. Introduction……………………………………………………………………….…...147 2. Materials and Methods……………………………………………………………..…148 2.1 n-Alkane standards 148 2.2 Sediment samples 149 2.3 Sample preparation for n-alkane analysis 149 2.4 Instrumentation 150 2.5 Optimization of the GC-C-IRMS results 152 3. Results and Discussion………………………………………....……………………...152 3.1 Optimized sample preparation 152 3.2 Correction factors for the GC-C-IRMS results 155 3.2.1 Drift-correction with CO2 155 3.2.2 Correction for amount dependence 155 3.2.3 Calibration against certified standards 158 3.2.4 Accuracy and precision of δ13C values of individual n-alkanes obtained by GC-C-IRMS measurements 159 3.3 Interpretation of δ13C values of individual n-alkanes in the sediment core Arg. D4 161 4. Conclusions…………………………………………………………………………….162 Acknowledgements 163 References 163 Acknowledgements…………………………………………………………………………167 Declaration………………………………………………………………………………….169 VI List of Tables Table 1-1: TOC/N ratios of litter and some plant samples collected from along a transect on the southern slopes of Mt. Kilimanjaro. Ratios around 20 and lower are typically found in the montane forest zone and cannot explain the soil TOC/N maxima (>20) obtained for the buried A horizons in profile TS01/2250. Litter and characteristic plants of the ericaceous zone generally reveal high TOC/N ratios. 37 Table 1-2: Radiocarbon dates of humic acids and one charcoal sample (HK) of mainly buried A horizons along a soil catena on the southern slopes of Mt. Kilimanjaro (Physical Institute of the University of Erlangen-Nürnberg, Germany). For details of the soil profiles see Fig. 1-5. 41 Table 2-1: Radiocarbon data and infrared stimulated luminescence data obtained for various sample material from the TPS. Analyses were carried out at the Leibniz Laboratory, Kiel (KIA), the Physical Department of the University of Erlangen (Erl.) and the GGA-Institute, Hannover (LUM). All ages are illustrated in stratigraphic position in Fig. 2-7A. 70 Table 5-1: Radiocarbon dates (KIA: Leibniz Laboratory, University of Kiel, Germany; Poz: Poznan radiocarbon Laboratory, Poland; Erl: Physical Department of the University of Erlangen, Germany). Calibration was outlined with quickcal2005 vers.1.4 (http://www.calpal-online.de). 128 Table 6-1: Drift- and amount-corrected δ13C values (‰) ± standard error for individual n-alkanes from the sediment core “Arg. D4” after calibration against n-tetracosane-d50 and n-eicosane-d42. 159 VII List of Figures Fig. I: Stratigraphy and geochemical results of profile TS01/2250. Black horizons reveal higher TOC contents and are therefore referred to as Ab horizons. Especially the 2 Ab and 4 Ab horizon are characterized by high TOC/N ratios, 13 maxima in BC, high nC31/nC27 ratios and more positive δ C values,