Assessing permafrost erosion in the Canadian Beaufort Sea, Herschel Island – a biomarker approach Master Thesis M.Sc. Marine Geoscience Submitted by: Thorsten Riedel Matriculation number: 2989087 Bremen, 18.05.2017 Supervisors: Prof. Dr. Gesine Mollenhauer Dr. Enno Schefuß Content List of tables............................................................................................................................ III List of figures .......................................................................................................................... IV Abstract ..................................................................................................................................... V 1. Introduction ...................................................................................................................... 1 1.1. Permafrost erosion in nearshore Arctic areas ................................................................... 1 1.2. Thesis objectives ................................................................................................................... 4 1.3. Biomarker outline ................................................................................................................. 5 1.3.1. Hopanes ......................................................................................................................... 5 1.3.2. n-alkanes ........................................................................................................................ 6 1.3.3. GDGT’s ......................................................................................................................... 7 2. Study area ......................................................................................................................... 8 2.1. Genesis and geological setting of Herschel Island ............................................................. 8 2.2. Potential sources of sediment ............................................................................................ 11 3. Material & Methods ...................................................................................................... 13 3.1. Yukon Coast soil/sediment samples .................................................................................. 13 3.1.1. Herschel Island ............................................................................................................ 14 3.1.1.1. Retrogressive thaw slump D ................................................................................................. 14 3.1.1.2. Collinson Head/Retrogressive thaw slump B ........................................................................ 15 3.1.2. Komakuk Beach/Yukon Coastal Plain ........................................................................ 16 3.1.3. Yukon Coast 2016 spring sediment samples ............................................................... 17 3.1.3.1. Surface sediment samples, Herschel Basin ........................................................................... 19 3.1.3.2. Sediment core PG 2303, Herschel Basin .............................................................................. 19 3.2. Preparation of biomarker samples ................................................................................... 20 3.2.1. Sample extraction ........................................................................................................ 20 3.2.2. Saponification .............................................................................................................. 20 3.2.3. Silica gel column chromatography .............................................................................. 21 3.2.4. Processing of GDGT fractions ..................................................................................... 21 3.3. Biomarker analysis ............................................................................................................. 21 3.3.1. GC-MS analysis ........................................................................................................... 21 3.3.2. GC-FID analysis .......................................................................................................... 23 3.3.3. HPLC analysis ............................................................................................................. 25 I 3.4. Preparation and analysis of radiocarbon samples .......................................................... 26 3.4.1. Acidification ................................................................................................................ 27 3.4.2. Graphitisation .............................................................................................................. 27 3.4.3. Accelerator mass spectrometry .................................................................................... 27 4. Results ............................................................................................................................. 28 4.1. TOC values .......................................................................................................................... 28 4.2. Hopane triterpenes ............................................................................................................. 28 4.3. n-alkanes .............................................................................................................................. 30 4.4. GDGT’s ............................................................................................................................... 32 4.5. Geochronology .................................................................................................................... 32 5. Discussion ....................................................................................................................... 37 5.1. Biomarker signature of sediment contributors to Herschel Basin ................................ 37 5.2. Spatial biomarker distribution in Herschel Basin ........................................................... 42 5.2.1. Hopanoid endmember model ....................................................................................... 42 5.2.2. F14C endmember model ............................................................................................... 47 5.3. Quantification of OM from Herschel Island .................................................................... 50 5.4. Temporal changes of sedimentation ................................................................................. 51 6. Conclusion ...................................................................................................................... 53 7. Acknowledgement .......................................................................................................... 55 8. References ....................................................................................................................... 56 II List of tables Table 3.1: Summary of soil samples from Herschel Island and Komakuk Beach .................. 15 Table 3.2: Summary of sediment samples from Herschel Basin ............................................. 17 Table 4.1: Radiocarbon results of all analysed soil and sediment samples ............................. 32 Table 4.1: continued ................................................................................................................. 34 Table 5.1: n-alkane and hopane biomarker data from Yunker et al. (1992) ............................ 38 Table 5.2: Hopanoid endmember model results of PG 2303 ................................................... 43 Table 5.3: Radiocarbon data of POC from the Mackenzie River and Herschel Basin ............ 46 Table 5.4: Summary of the hopanoid and the F14C endmember model ................................... 49 Table 5.6: Quantified results of sediments in Herschel Basinl ................................................ 50 III List of figures Fig. 1.1: Permafrost distribution of the circumpolar Arctic ....................................................... 1 Fig. 1.2: Change of the mean air temperature in the Arctic ....................................................... 2 Fig. 1.3: Temperature change in the Arctic ............................................................................... 3 Fig. 1.4: Schematic view of the diagenetic succession of hopanes ........................................... 5 Fig. 1.5: Saturate fraction chromatogram of sample PG 2303-7/1-2 ......................................... 7 Fig. 1.6: GDGT structure ........................................................................................................... 7 Fig. 2.1: Overview of the study area .......................................................................................... 8 Fig. 2.2: Bathymetry of Herschel Basin ..................................................................................... 9 Fig. 2.3: Thaw slump D ........................................................................................................... 10 Fig 2.4: Satellite images of the southern Beaufort Sea ............................................................ 11 Fig. 3.1: Methodical approach of the COPER project ............................................................. 13 Fig. 3.2: Glaciotectonic deformation in deposits of thaw slump D ......................................... 14 Fig. 3.3: Coastal outcrop on Komakuk Beach ......................................................................... 16 Fig. 3.4: The sediment core PG