Browsing by Subject "ASTER"

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Access status: Open Access ,
Mapping and assessment of geological lineaments with the contribution of Earth observation data - a case study of the Zaer Granite Massif, Western Moroccan Meseta
(Wydawnictwa AGH, 2023) Zoraa, Noura; Raji, Mohammed; El Hadi, Hassan; Maimouni, Soufiane; Si Mhamdi, Hicham; Reddad, Aicha; Zahour, Ghalem; Ait-Yazza, Achraf
The Zaer granitic massif is one of the most important Variscan granitoids in the Central Zone of the Western Moroccan Meseta. It is characterized by a deformation which is manifested by a network of fractures of different scales. Thanks to the technology currently available, many geological studies rely heavily on the mapping of geological lineaments, especially in structural geology. This has become more reliable with access to earth observation data using optical and radar sensors as well as the various remote sensing techniques. Therefore, the objective of this work is to determine the potential of Landsat 8, ASTER, Sentinel 2 and radar Sentinel 1 datasets using the automatic method to extract lineaments. Furthermore, this work focuses on quantitative lineament analysis to determine lineament trends and subsequently compare them with global and regional tectonic movement trends. The lineaments obtained through different satellite images were validated by including the shaded relief maps, the slope map, the correlation with the pre-existing faults in the geological maps as well as the field investigation. Comparison of these results indicates that Sentinel 1 imagery provides a better correlation between automated extraction lineaments and major fault zones. Thus, Sentinel 1 data is more effective in mapping geological lineaments. The final lineament map obtained from the VH and VV polarizations shows two major fault systems, mainly oriented NE-SW and NW-SE to NNW-SSE.
Access status: Open Access ,
Processing and analysis of aster and landsat 8 scenes to aid in geological mapping: a case study of Murchison Greenstone Belt area, South Africa
(Wydawnictwa AGH, 2020) Thomas, Abraham
This paper presents processing and analysis results of ASTER and Landsat 8 scenes to aid in geological mapping of Murchison Greenstone Belt region of Limpopo Province, South Africa. Images of ASTER acquired in 2005 and 2006 and Landsat 8 acquired in 2019 were downloaded and subset covering 5 mapping sheets was extracted. Images of different band ratios and band combinations were experimented using ENVI and SNAP software to identify suitable band/band ratio combinations to produce FCCs that enabled discrimination of lithology, structural features, lineaments, alteration and iron oxides, land/water, surface features, vegetation cover and healthy vegetation etc. Using DEM data, slope and shaded relief were also prepared that enabled the identification of the extent of protruded outcrops, some structural features and lineaments using different FCC displays. These datasets prepared in ENVI file format were later exported to GeoTiff/Imagine file for display in ArcMap by the mapping geologists. FCCs made in various band combinations, ratio combination and also with slope are useful in discriminating geology, structural features and protruded outcrops including dykes that are not so visible in a true colour image of the same resolution. This study could illustrate the usefulness of remote sensing analysis to aid in geological mapping using freely available ASTER and Landsat 8 data.
Access status: Open Access ,
Satellite data based abundance mapping of mafic and ultramafic rocks in Mettupalayam, Tamil Nadu, India
(Wydawnictwa AGH, 2021) Libeesh, Nharakkat Kalarikkal; Arivazhagan, Sundaram
The mafic and ultramafic rocks of Mettupalayam belong to the southern granulite terrain of India, which is concomitant with vital economic resources. The advantage of Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) data for mapping the litho units are exploited well here for differentiating the rock units with the aid of band combination (1, 3, 6), principal component analysis (5, 1, 6) and band ratioed band combination (2/3, 3/2, 1/5 and (9–8)/1, (8–6)/2, and (9–6)/3). As part of the field study, the collection of samples and ground control points were carried out and in addition to that, the generation of laboratory reflectance spectra for samples was achieved. The Spectral Angle Mapper (SAM) and Support Vector Machine (SVM) were performed using ASTER data with the aid of spectra obtained from the laboratory conditions to demarcate the abundance of mafic and ultramafic rocks of the area. The XRF method was used to retrieve the major oxides of the field-collected samples and the spectral absorption characters are validated with it. The results show a vibrant interpretation of the litho units.