Lithological mapping on the Antarctic Peninsula using advanced spaceborne thermal emission and reflection radiometer (ASTER) data

The Antarctic Peninsula is larger than the UK and with limited geological mapping campaigns since the 1940s significant gaps in coverage remain, particularly in areas where access is difficult. Remote sensing offers potential for improving geological mapping on the peninsula but has not been used for these purposes. This thesis describes the use of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for lithological mapping of predominantly calc-alkaline subduction-related igneous rocks on the Antarctic Peninsula. The research encompassed lithological mapping of four study areas selected to provide an appropriate test of the potential of ASTER. Processing of ASTER reflectance and thermal emission data used spectral enhancement procedures and the matched filter (MF) spectral mapping method. This was supported by reflectance spectroscopy of rock samples, Hyperion data, thin section petrography, geochemical data for acid volcanic rocks, and fieldwork on Adelaide Island. The research shows although outcrop is limited in the polar context, weathering effects and vegetation cover do not cause significant problems. ASTER provides a range of lithologic information enabling validation of inferred field mapping and new observations of unmapped geology in the study areas. Granitoids and silicic volcanic rocks display distinctive spectral properties and are newly identified from unmapped parts of the Oscar II, Foyn, and Lassiter coasts. Areas of localised alteration in these rocks are readily discriminated based on the distinctive absorption features of the alteration mineral assemblages. ASTER is less successful at discriminating intermediate-mafic igneous, sedimentary and metamorphic lithologies that display more ambiguous spectral features. For these rocks lithological mapping is strongly reliant on existing field observations to resolve ambigious results. The research shows that although ASTER is limited in its ability to uniquely discriminate different rock types it can provide important lithological information in support of geological mapping on the Antarctic Peninsula

Quantification and analysis of icebergs in a tidewater glacier fjord using an object-based approach

Tidewater glaciers are glaciers that terminate in, and calve icebergs into, the ocean. In addition to the influence that tidewater glaciers have on physical and chemical oceanography, floating icebergs serve as habitat for marine animals such as harbor seals (Phoca vitulina richardii). The availability and spatial distribution of glacier ice in the fjords is likely a key environmental variable that influences the abundance and distribution of selected marine mammals; however, the amount of ice and the fine-scale characteristics of ice in fjords have not been systematically quantified. Given the predicted changes in glacier habitat, there is a need for the development of methods that could be broadly applied to quantify changes in available ice habitat in tidewater glacier fjords. We present a case study to describe a novel method that uses object-based image analysis (OBIA) to classify floating glacier ice in a tidewater glacier fjord from high-resolution aerial digital imagery. Our objectives were to (i) develop workflows and rule sets to classify high spatial resolution airborne imagery of floating glacier ice; (ii) quantify the amount and fine-scale characteristics of floating glacier ice; (iii) and develop processes for automating the object-based analysis of floating glacier ice for large number of images from a representative survey day during June 2007 in Johns Hopkins Inlet (JHI), a tidewater glacier fjord in Glacier Bay National Park, southeastern Alaska. On 18 June 2007, JHI was comprised of brash ice ([Formula: see text] = 45.2%, SD = 41.5%), water ([Formula: see text] = 52.7%, SD = 42.3%), and icebergs ([Formula: see text] = 2.1%, SD = 1.4%). Average iceberg size per scene was 5.7 m2 (SD = 2.6 m2). We estimate the total area (± uncertainty) of iceberg habitat in the fjord to be 455,400 ± 123,000 m2. The method works well for classifying icebergs across scenes (classification accuracy of 75.6%); the largest classification errors occur in areas with densely-packed ice, low contrast between neighboring ice cover, or dark or sediment-covered ice, where icebergs may be misclassified as brash ice about 20% of the time. OBIA is a powerful image classification tool, and the method we present could be adapted and applied to other ice habitats, such as sea ice, to assess changes in ice characteristics and availability

Lithological mapping on the Antarctic Peninsula using advanced spaceborne thermal emission and reflection radiometer (ASTER) data

The Antarctic Peninsula is larger than the UK and with limited geological mapping campaigns since the 1940s significant gaps in coverage remain, particularly in areas where access is difficult. Remote sensing offers potential for improving geological mapping on the peninsula but has not been used for these purposes. This thesis describes the use of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for lithological mapping of predominantly calc-alkaline subduction-related igneous rocks on the Antarctic Peninsula. The research encompassed lithological mapping of four study areas selected to provide an appropriate test of the potential of ASTER. Processing of ASTER reflectance and thermal emission data used spectral enhancement procedures and the matched filter (MF) spectral mapping method. This was supported by reflectance spectroscopy of rock samples, Hyperion data, thin section petrography, geochemical data for acid volcanic rocks, and fieldwork on Adelaide Island. The research shows although outcrop is limited in the polar context, weathering effects and vegetation cover do not cause significant problems. ASTER provides a range of lithologic information enabling validation of inferred field mapping and new observations of unmapped geology in the study areas. Granitoids and silicic volcanic rocks display distinctive spectral properties and are newly identified from unmapped parts of the Oscar II, Foyn, and Lassiter coasts. Areas of localised alteration in these rocks are readily discriminated based on the distinctive absorption features of the alteration mineral assemblages. ASTER is less successful at discriminating intermediate-mafic igneous, sedimentary and metamorphic lithologies that display more ambiguous spectral features. For these rocks lithological mapping is strongly reliant on existing field observations to resolve ambigious results. The research shows that although ASTER is limited in its ability to uniquely discriminate different rock types it can provide important lithological information in support of geological mapping on the Antarctic Peninsula.EThOS - Electronic Theses Online ServiceNERCAntarctic Funding Initiaitive (AFI) Collaborative Gearing SchemeGBUnited Kingdo

Lithologic mapping in the Oscar II Coast area, Graham Land, Antarctic Peninsula using ASTER data

The results of the first attempt to use Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data for the purposes of lithologic mapping on the Antarctic Peninsula are presented for an area on the Oscar II Coast, eastern Graham Land. This study included undertaking laboratory reflectance spectroscopy of similar to 70 rock samples from the study area and spectral lithologic analysis of two ASTER scenes. Spectra of the granitoids, silicic volcanic/volcaniclastic and terrestrial sedimentary rocks in the study area display a limited range of absorption features associated with muscovite, smectite and chlorite that are generally present as the alteration products of regional metamorphism. ASTER data analysis was undertaken using the reflective bands of the Level 1B registered radiance at-sensor data and the standard thermal infrared (TIR) emissivity product (AST05). For both wavelength regions, standard qualitative image processing methods were employed to define image end-members that were used as reference within Matched Filter (MF) processing procedures. The results were interpreted with reference to existing field observations, and photogeologic analysis of the ASTER visible to near-infrared (VNIR)/shortwave infrared (SWIR) data was used to resolve ambiguities in the spectral mapping results. The results have enabled the discrimination of most of the major lithologic groups within the study area as well as delineation of hydrothermal alteration zones of propylitic, and argillic grades associated with the Mesozoic Mapple Formation volcanics. The results have extended the mapped coverage of the Mapple Formation into un-investigated regions further north and validated previously inferred geological observations concerning other rocks throughout the study area. The outcomes will enable important revisions to be made to the existing geological map of the Oscar II Coast and demonstrate that ASTER data offers potential for improving geological mapping coverage across the Antarctic Peninsula

Summary of classification error analysis results.

<p>Summary of classification error analysis results.</p

Spatial and numerical distribution of brash ice within Johns Hopkins Inlet.

<p>(a)Distribution of brash ice in Johns Hopkins Inlet on 18 June 2007, as a percentage of each aerial image. Histogram (blue) and probability density functions (PDF) (red) for percent coverage of brash ice (b) and water (c).</p

Workflow from aerial image acquisition to generation of distribution maps and statistics for seals and icebergs.

<p>Workflow from aerial image acquisition to generation of distribution maps and statistics for seals and icebergs.</p