Chemical weathering on selected nunataks in western Dronning Maud Land, Antarctica
- Authors: Knox, Jenna Tracy
- Date: 2018
- Subjects: Glacial climates -- Antarctica -- Queen Maud Land , Glaciology -- Antarctica -- Queen Maud Land , Chemical weathering -- Antarctica -- Queen Maud Land , Atmospheric carbon dioxide -- Environmental aspects , Climatic changes -- Antarctica -- Queen Maud Land , Nunataks -- Antarctica -- Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61658 , vital:28046
- Description: High latitude areas are sensitive to the impacts of climate change, and it is expected that the impact of greenhouse warming will be much higher in the polar regions than in any other climatic zones, with the most highly affected area being that of the Antarctic rim (Barsch, 1993). Weathering and pedogenic processes respond to variations in climate, with models predicting that chemical weathering may increase synchronously with global carbon dioxide levels increase, due to dissolution rates and the erosional impact of hydrological cycles in warming climates (Anderson & Anderson, 2010). As liquid water becomes more available in Antarctica the potential for chemical weathering, due to a less moisture-limited environment and increased temperatures, increases (Convey et al., 2009). Weathering processes are important for soil formation and the production of fine-grained material, with chemical weathering being an active constituent of this. Increased rates of soil formation are likely to occur, with global climate changes resulting in greater chemical weathering occurring in Antarctica. Opportunistic sampling was conducted during the Austral summer of 2016/2017, whereby rock, snow and meltwater samples were taken at various sites within the western portion of Dronning Maud Land of Antarctica. Rock samples were placed in resin, and cut with a diamond saw to create thin sections. Optical microscopy and scanning transmission electron microscopy (STEM) were used to analyse mineral weight percentage with depth. Twelve soil samples were dried and weighed, sieved and statistically represented according to particle size. Inductively coupled plasma mass spectrometry (ICP-MS) determined the geochemical analysis for 10 water and snow samples. Rock hardness was inferred through the use of an Equotip, with rebound values recorded for multiple rock faces and samples. Thermal regimes of rock temperature was further recorded using a FLIR infrared camera, and documented for each rock face over a 24 hour period at 2 hourly intervals. The products of increased chemical weathering were evident from particle size analysis; samples were very poorly sorted in nature, and undergo in situ weathering, whereby products were not removed by erosional processes. Weathering rinds were found to be siliceous and ferric, depending on parent lithology. Ferric ratios increased in wt.% from the substrate rock to the external surface, creating the red, iron rich crusts noted on the hand specimens. The observable chemical weathering was found adjacent to intrusions through Precambrian dolerites. Geochemical analysis revealed thin, carbonaceous features, with impurity-rich layers, characteristic of speleothem formation. Carbonaceous layers did not follow underlying substrate features, rather deposited at the external surface, upon which, further precipitation growth could occur, creating karst features. Extensive gypsum coatings (>2mm) under BSE imagery were identified, with the abundance of gypsum salts (below surface level) and rock coatings indicating active sulphuric acid weathering, in western Dronning Maud Land, Antarctica. Were mechanical processes faster than chemical, weathering rinds and solution features on silicate rocks would be uncommon in the Antarctic, periglacial landscape. However, this is not the case as the existence of these landforms implies that chemical weathering may occur faster than mechanical weathering processes (Pope et al., 1995). In a changing world, one needs to monitor these processes at a micro-scale in order to fully understand how periglacial environments react to global climatic changes, and the subsequent impacts on these sensitive environments.
- Full Text:
- Date Issued: 2018
- Authors: Knox, Jenna Tracy
- Date: 2018
- Subjects: Glacial climates -- Antarctica -- Queen Maud Land , Glaciology -- Antarctica -- Queen Maud Land , Chemical weathering -- Antarctica -- Queen Maud Land , Atmospheric carbon dioxide -- Environmental aspects , Climatic changes -- Antarctica -- Queen Maud Land , Nunataks -- Antarctica -- Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61658 , vital:28046
- Description: High latitude areas are sensitive to the impacts of climate change, and it is expected that the impact of greenhouse warming will be much higher in the polar regions than in any other climatic zones, with the most highly affected area being that of the Antarctic rim (Barsch, 1993). Weathering and pedogenic processes respond to variations in climate, with models predicting that chemical weathering may increase synchronously with global carbon dioxide levels increase, due to dissolution rates and the erosional impact of hydrological cycles in warming climates (Anderson & Anderson, 2010). As liquid water becomes more available in Antarctica the potential for chemical weathering, due to a less moisture-limited environment and increased temperatures, increases (Convey et al., 2009). Weathering processes are important for soil formation and the production of fine-grained material, with chemical weathering being an active constituent of this. Increased rates of soil formation are likely to occur, with global climate changes resulting in greater chemical weathering occurring in Antarctica. Opportunistic sampling was conducted during the Austral summer of 2016/2017, whereby rock, snow and meltwater samples were taken at various sites within the western portion of Dronning Maud Land of Antarctica. Rock samples were placed in resin, and cut with a diamond saw to create thin sections. Optical microscopy and scanning transmission electron microscopy (STEM) were used to analyse mineral weight percentage with depth. Twelve soil samples were dried and weighed, sieved and statistically represented according to particle size. Inductively coupled plasma mass spectrometry (ICP-MS) determined the geochemical analysis for 10 water and snow samples. Rock hardness was inferred through the use of an Equotip, with rebound values recorded for multiple rock faces and samples. Thermal regimes of rock temperature was further recorded using a FLIR infrared camera, and documented for each rock face over a 24 hour period at 2 hourly intervals. The products of increased chemical weathering were evident from particle size analysis; samples were very poorly sorted in nature, and undergo in situ weathering, whereby products were not removed by erosional processes. Weathering rinds were found to be siliceous and ferric, depending on parent lithology. Ferric ratios increased in wt.% from the substrate rock to the external surface, creating the red, iron rich crusts noted on the hand specimens. The observable chemical weathering was found adjacent to intrusions through Precambrian dolerites. Geochemical analysis revealed thin, carbonaceous features, with impurity-rich layers, characteristic of speleothem formation. Carbonaceous layers did not follow underlying substrate features, rather deposited at the external surface, upon which, further precipitation growth could occur, creating karst features. Extensive gypsum coatings (>2mm) under BSE imagery were identified, with the abundance of gypsum salts (below surface level) and rock coatings indicating active sulphuric acid weathering, in western Dronning Maud Land, Antarctica. Were mechanical processes faster than chemical, weathering rinds and solution features on silicate rocks would be uncommon in the Antarctic, periglacial landscape. However, this is not the case as the existence of these landforms implies that chemical weathering may occur faster than mechanical weathering processes (Pope et al., 1995). In a changing world, one needs to monitor these processes at a micro-scale in order to fully understand how periglacial environments react to global climatic changes, and the subsequent impacts on these sensitive environments.
- Full Text:
- Date Issued: 2018
On high-altitude and high- latitude frost environments
- Authors: Hansen, Christel Dorothee
- Date: 2018
- Subjects: Frost -- Drakensberg Mountains , Frost -- Prince Edward Islands -- Marion Island , Frost -- Antarctica -- Queen Maud Land , Climatic geomorphology -- Southern Hemisphere , Permafrost -- Southern Hemisphere , Periglacial processes -- Southern Hemisphere , Frost environments -- Southern Hemisphere
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62383 , vital:28169
- Description: Frost environments occur throughout the world, with associated processes occurring across climatic zones. Climatic geomorphology proposes that climatic zones, largely derived from annual average air temperature and precipitation values, have specific landforms and processes active within that zone. This study offers unique insights into the frost environments of three locations in the Southern Hemisphere, namely the Eastern Cape Drakensberg of South Africa, sub-Antarctic Marion Island, and Dronning Maud Land of Antarctica. The Drakensberg ranges from temperate to alpine, Marion Island is hyper-maritime, and Dronning Maud Land a polar desert. Drivers and forcings on the ground frost regime are identified, as are future climatic scenarios. Altitude and latitude were identified as the most important locational drivers, while air temperature showed highest correlation with freezing events. The initiation of a freeze event correlated strongly with maximum ground temperatures. Vegetation cover was found to ameliorate frost cycles, thereby increasing ground temperatures. Dronning Maud Land of Antarctica is characterised by annual frost (permafrost), with limited seasonal thaw in summer. Thawing cycles reflected the depth of the active layer, which ranged from just under 60 cm for Robertskollen (at lowest altitude) to less than 15 cm on Slettfjell (at greatest altitude). Marion Island had the most active frost environment, exhibiting both seasonal frost, and ubiquitous shallow diurnal frost cycles. The Drakensberg were largely frost-free, with limited seasonal frost and few diurnal freeze- thaw events. Diurnal frost processes were found to be azonal, and present at all three study locations. Evidence of landforms derived from diurnal frost processes were evident in each zone. Equifinality/convergence of form was present to a degree. The presence of patterned ground, which was not wholly derived from frost processes, suggests a measure of equifinality. Furthermore, openwork block deposits, of which not all are either blockstreams nor blockfields, are not necessarily the result of frost processes. The periglacial environment is poorly defined and methods to delineate this environment, as well as other climatic zones, should include additional parameters. Delineating zones on annual (and limited) monthly averages based on predominantly temperature, is not sufficient. While concepts of climatic geomorphology may be applied in a general sense, this framework is not suited to working at smaller scales. Specifically, periglacial environments should be delineated using ground moisture, as well as air temperature. Furthermore, vegetation and snow cover are important, as are soil textural properties.
- Full Text:
- Date Issued: 2018
- Authors: Hansen, Christel Dorothee
- Date: 2018
- Subjects: Frost -- Drakensberg Mountains , Frost -- Prince Edward Islands -- Marion Island , Frost -- Antarctica -- Queen Maud Land , Climatic geomorphology -- Southern Hemisphere , Permafrost -- Southern Hemisphere , Periglacial processes -- Southern Hemisphere , Frost environments -- Southern Hemisphere
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62383 , vital:28169
- Description: Frost environments occur throughout the world, with associated processes occurring across climatic zones. Climatic geomorphology proposes that climatic zones, largely derived from annual average air temperature and precipitation values, have specific landforms and processes active within that zone. This study offers unique insights into the frost environments of three locations in the Southern Hemisphere, namely the Eastern Cape Drakensberg of South Africa, sub-Antarctic Marion Island, and Dronning Maud Land of Antarctica. The Drakensberg ranges from temperate to alpine, Marion Island is hyper-maritime, and Dronning Maud Land a polar desert. Drivers and forcings on the ground frost regime are identified, as are future climatic scenarios. Altitude and latitude were identified as the most important locational drivers, while air temperature showed highest correlation with freezing events. The initiation of a freeze event correlated strongly with maximum ground temperatures. Vegetation cover was found to ameliorate frost cycles, thereby increasing ground temperatures. Dronning Maud Land of Antarctica is characterised by annual frost (permafrost), with limited seasonal thaw in summer. Thawing cycles reflected the depth of the active layer, which ranged from just under 60 cm for Robertskollen (at lowest altitude) to less than 15 cm on Slettfjell (at greatest altitude). Marion Island had the most active frost environment, exhibiting both seasonal frost, and ubiquitous shallow diurnal frost cycles. The Drakensberg were largely frost-free, with limited seasonal frost and few diurnal freeze- thaw events. Diurnal frost processes were found to be azonal, and present at all three study locations. Evidence of landforms derived from diurnal frost processes were evident in each zone. Equifinality/convergence of form was present to a degree. The presence of patterned ground, which was not wholly derived from frost processes, suggests a measure of equifinality. Furthermore, openwork block deposits, of which not all are either blockstreams nor blockfields, are not necessarily the result of frost processes. The periglacial environment is poorly defined and methods to delineate this environment, as well as other climatic zones, should include additional parameters. Delineating zones on annual (and limited) monthly averages based on predominantly temperature, is not sufficient. While concepts of climatic geomorphology may be applied in a general sense, this framework is not suited to working at smaller scales. Specifically, periglacial environments should be delineated using ground moisture, as well as air temperature. Furthermore, vegetation and snow cover are important, as are soil textural properties.
- Full Text:
- Date Issued: 2018
Periglacial landforms of the Ahlmannryggen and Jutulsessen areas of western Dronning Maud land, Antarctica
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
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