Modern to Late Pleistocene Stable Isotope Climatology of Alaska
نویسندگان
چکیده
...................................................................................................................... iii ACKNOWLEDGMENTS ................................................................................................. vi TABLE OF CONTENTS ................................................................................................. viii LIST OF TABLES ............................................................................................................. xi LIST OF FIGURES .......................................................................................................... xii CHAPTER 1 DISSERTATION OVERVIEW ................................................................... 1 Purpose ................................................................................................................................ 1 Chapter 2 synopsis .............................................................................................................. 1 Chapter 3 synopsis .............................................................................................................. 2 Chapter 4 synopsis .............................................................................................................. 2 CHAPTER 2 MODERN SURFACE WATER STABLE ISOTOPE CLIMATOLOGY OF ALASKA ................................................................. 5 Abstract ............................................................................................................................... 5 Introduction ......................................................................................................................... 6 Physiography and climate of Alaska ............................................................................... 8 Methods............................................................................................................................... 8 Results and Interpretation ................................................................................................. 11 Isoscape of Alaskan surface waters .............................................................................. 11 Isoscape derivation.................................................................................................... 11 Isoscape residuals...................................................................................................... 14 Spatial variability in surface water stable isotopes ....................................................... 14 Temperature effect .................................................................................................... 15 Cumulative precipitation amount effect.................................................................... 16 Altitude and latitude effect ........................................................................................ 17.............................................................................................................................. 5 Introduction ......................................................................................................................... 6 Physiography and climate of Alaska ............................................................................... 8 Methods............................................................................................................................... 8 Results and Interpretation ................................................................................................. 11 Isoscape of Alaskan surface waters .............................................................................. 11 Isoscape derivation.................................................................................................... 11 Isoscape residuals...................................................................................................... 14 Spatial variability in surface water stable isotopes ....................................................... 14 Temperature effect .................................................................................................... 15 Cumulative precipitation amount effect.................................................................... 16 Altitude and latitude effect ........................................................................................ 17 ix Distance from the Pacific effect ................................................................................ 18 Implications for paleoclimatic reconstructions ............................................................. 21 Conclusion ........................................................................................................................ 22 CHAPTER 3 THERMAL STRATIGRAPHY OF THE FOX PERMAFROST TUNNEL ................................................................ 45 Abstract ............................................................................................................................. 45 Introduction ....................................................................................................................... 46 Tunnel geology ................................................................................................................. 49 Tunnel stratigraphy ....................................................................................................... 49 Tunnel C ages ............................................................................................................. 50 Methods............................................................................................................................. 52 Results ............................................................................................................................... 55 Ice wedge and pool ice stratigraphy.............................................................................. 55 Ice wedge and pool ice C dating ................................................................................ 58 Timing of freeze and melt events .................................................................................. 60 Discussion ......................................................................................................................... 65 Approximate timing of freeze and melt events ............................................................. 65 Freeze event 1 – 25.9 to 21.5 cal ka BP .................................................................... 66 Freeze event 2 <25.9 to 21.5 cal ka BP .................................................................. 67 Melt event 1 – 21.5 to 17.9 cal ka BP ....................................................................... 67 Freeze event 3 – 17.9 to 12.9 cal ka BP .................................................................... 69 Freeze event 4 <17.9 to 12.9 cal ka BP .................................................................. 70 Freeze event 5 <17.9 to 12.9 cal ka BP .................................................................. 71 Implications for dating carbon in the permafrost environments ................................... 71 Summary of thermal events in the Permafrost Tunnel ................................................. 72 Conclusion ........................................................................................................................ 72............................................................................................................................ 45 Introduction ....................................................................................................................... 46 Tunnel geology ................................................................................................................. 49 Tunnel stratigraphy ....................................................................................................... 49 Tunnel C ages ............................................................................................................. 50 Methods............................................................................................................................. 52 Results ............................................................................................................................... 55 Ice wedge and pool ice stratigraphy.............................................................................. 55 Ice wedge and pool ice C dating ................................................................................ 58 Timing of freeze and melt events .................................................................................. 60 Discussion ......................................................................................................................... 65 Approximate timing of freeze and melt events ............................................................. 65 Freeze event 1 – 25.9 to 21.5 cal ka BP .................................................................... 66 Freeze event 2 <25.9 to 21.5 cal ka BP .................................................................. 67 Melt event 1 – 21.5 to 17.9 cal ka BP ....................................................................... 67 Freeze event 3 – 17.9 to 12.9 cal ka BP .................................................................... 69 Freeze event 4 <17.9 to 12.9 cal ka BP .................................................................. 70 Freeze event 5 <17.9 to 12.9 cal ka BP .................................................................. 71 Implications for dating carbon in the permafrost environments ................................... 71 Summary of thermal events in the Permafrost Tunnel ................................................. 72 Conclusion ........................................................................................................................ 72 CHAPTER 4 VARIABLE LATE PLEISTOCENE PALEOCLIMATE IN ALASKA FROM HIGH-RESOLUTION O OF PERMAFROST ICE WEDGES SUGGESTS NORTH ATLANTIC FORCING ............................................................................ 82 Abstract ............................................................................................................................. 82............................................................................................................................ 82
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