THE GEOLOGY AND GEOMORPHOLOGY OF THE DENTON HILLS, SOUTHERN VICTORIA LAND, ANTARCTICA A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science in Geology in the University of Canterbury by N. J. Carson University of Canterbury 2012 Dedication I would like to dedicate this thesis to two very special people who passed away during this research. Benjamin Andrew Carson 09/05/1984 – 25/04/2010 William Andrew Carson 28/01/1922 - 09/12/2009 ii Abstract This research is an integrated geological and geomorphological study into the Denton Hills area. The study area is part of the foothills to the Transantarctic Mountains, which divides East and West Antarctica, allowing an opportunity to investigate glacial events from both sides. As the study area is ice-free, it has allows good examination of the bedrock geology and has preserved geomorphological features allowing them to be examined and sampled. Comprehensive geological map and geomorphological maps have been produced, extending the knowledge into the spatial distribution of units and features. Both the geological and geomorphological maps reveal a complex history of evolution. The original geological units have been subjected to deformation and intrusion of large plutons. The geomorphological mapping shows ice has flowed in alternate direction through the valleys, and the valleys have had long periods where they have been occupied by large proglacial lakes. As the Antarctic ice sheets expanded they flowed into the valleys either from the west, the Royal Society Range draining the East Antarctic Ice Sheet or from the east, McMurdo Sound. Ice would flow from McMurdo Sound when the West Antarctic Ice Sheet expanded causing the grounding line of the ice sheet to move north through the Ross Sea. Surface exposure dating completed during the study has correlated the timing of glacial events to global cycles. The dating confirmed the presence of the large proglacial lake during the Last Glacial Maximum in the Miers Valley, which drained about 14 ka. The Garwood Glacier has also been directly linked to the Last Glacial Maximum with a moraine forming about 22 ka. The dating has also shown that during the Last Glacial Maximum there was little fluctuation in the size of glaciers draining the East Antarctic Ice Sheet, with features being date to the onset of the Last Glacial Maximum. iii Table of Contents Dedication ....................................................................................................................................... ii Abstract .......................................................................................................................................... iii Table of Figures .............................................................................................................................. ix Table of Tables .............................................................................................................................. xii 1. Introduction ............................................................................................................................... 1 1.1. Scope of research ............................................................................................................... 1 1.2. Association with IPY project (nzTABS) ........................................................................... 2 1.3. Methodology ...................................................................................................................... 3 1.4. Study Area ......................................................................................................................... 4 1.5. Regional Geological Setting .............................................................................................. 7 1.6. Antarctic Climate ............................................................................................................... 9 1.7. Styles of Antarctic Glaciation .......................................................................................... 10 1.7.1. Styles of Glaciation .................................................................................................. 10 1.7.2. Alpine Glaciers ......................................................................................................... 14 2. Previous Studies ...................................................................................................................... 15 2.1. Introduction ..................................................................................................................... 15 2.2. Geological Studies ........................................................................................................... 15 2.2.1. Early Explorers ......................................................................................................... 15 2.2.2. IGY (International Geophysical Year) Research ..................................................... 16 2.2.3. Research post IGY ................................................................................................... 19 2.2.4. Otago University Geology Department Antarctic Research .................................... 21 2.3. Geomorphological ........................................................................................................... 25 2.3.1 Glacial Geomorphology ........................................................................................... 25 iv 2.3.2. Lake Deposits ........................................................................................................... 28 2.3.3. Alluvial Deposits ...................................................................................................... 36 2.3.4. Aeolian Deposits ...................................................................................................... 37 2.4. Cosmogenic (Surface Exposure Dating) ......................................................................... 39 3. Geology ................................................................................................................................... 42 3.1. Introduction ..................................................................................................................... 42 3.2. Methodology .................................................................................................................... 42 3.3. Koettlitz Group ................................................................................................................ 42 3.3.1. Gneiss ....................................................................................................................... 43 3.3.2. Schist ........................................................................................................................ 45 3.3.3. Marble ...................................................................................................................... 45 3.4. Granitoids ........................................................................................................................ 47 3.5. Mafic Intrusions ............................................................................................................... 48 3.6. Deformation ..................................................................................................................... 50 3.7. Quaternary Deposits ........................................................................................................ 51 4. Glacial Geomorphology .......................................................................................................... 52 4.1. Introduction ..................................................................................................................... 52 4.2. Methodology .................................................................................................................... 52 4.2.1. Field Geomorphic Mapping ..................................................................................... 52 4.2.2. Digitising Geomorphic Maps ................................................................................... 52 4.3. Lakes, Rivers and Streams............................................................................................... 53 4.3.1. Lakes ........................................................................................................................ 53 4.3.2. Rivers/Streams ......................................................................................................... 54 4.4. Polygonal Patterned Ground ............................................................................................ 55 4.5. Desert Pavement .............................................................................................................. 56 v 4.6. Quaternary Faults ............................................................................................................ 57 4.7. Mass Movement .............................................................................................................. 58 4.7.1. Alluvial Fans ............................................................................................................ 58 4.7.2. Colluvial Deposits .................................................................................................... 59 4.8. Wind Processes ................................................................................................................ 60 4.8.1. Aeolian Deposits .....................................................................................................