Faculty of Engineering, Earth Resources Engineering

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Browsing Faculty of Engineering, Earth Resources Engineering by Author "Abeysinghe, AMKB"

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    item: Thesis-Abstract
    Development of conceptual geological model for the formation of hot water springs in Sri Lanka
    Premasiri, HMR; Wijesekara, DS; Weerawarnakula, S; Puswewala, UGA; Abeysinghe, AMKB
    As natures wonderful gift, several hot water springs occur in Sri Lanka though it does not fall within very active tectonic zone in the earth. They are mostly confined to the eastern sector of the island. However, hot water springs at Mahapelassa off Embilipitiya, Kanniyai off Trincomalee and Mahaoya are well known to people. These thermal springs show their out flow temperature ranging between 34°C to 56°C. The hottest springs lie at Kapurella (56°C), followed by Mahaoya (55°C), Marangala-Wahawa close to Padiyatalawa (42-45 ° C ), Mahapelassa (44-46 DC) and Nelumwewa, which was known earlier as Madawewa and now under a lake, records 45° C in mud samples (Fonseka 1994). The present research was aimed out mainly to model the formation of hot water springs in Sri Lanka based on geological and tectonic settings using geological, geophysical and Remote Sensing techniques while evaluating the hot water springs for their potential as energy resources or development as places for eco-tourism. Geological, structural and tectonic setting of the areas have been studied using geological, geochemical and geophysical techniques. Both field and libratory studies were carried out in order to compile geological and geophysical profiles and to determine geochemical and physical parameters of hot water springs in Sri Lanka. According to the results of this study, the major boundary between Highland Complex and Vijayan Complex show multiple thrust planes and shear zones showing imbrecated lithological slices of both Highland Complex and Vijayan Complex. Other than the ductile structures, brittle fractures, joints and fault planes extend as mega lineament for several kilometers. These lineaments produce good secondary aquifer conditions with adequate porosity. The surface mapping and geophysical evidence of the lineaments show that they are very deep and are interconnected. Therefore, they offer better pathways for surface water to percolate deep levels and return upwards with adequate pressure to reach the surface after heating. These structurally controlled hot water springs in Sri Lanka are associated with deep geologically weak zones of fracture or fault systems within the tectonically active thrust boundary. According to geochemical parameters and field evidence, hot water springs in Sri Lanka can be divided into three groups, Groupl: Mahapelassa Group 2: Kapurella, Mahaoya, Padiyatalwa , Palanoya and other around the Mahiyangana, Ampara and Group 3: Kannyai, Rathkhiriya and Adampane areas.). According to the chemical and physical parameters of hot water it can be concluded that Group (1) and Grou (3) are more suitable for therapeutic uses and have a good potential for development for eco-tourism. The Group (2) has hot water with low contaminations of salt, and show fairly high potential for generation of geothermal energy
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    item: Thesis-Full-text
    Relationship between los angeles abrasion value and mineralogy of rocks
    Dayarathna, IWTP; Puawawala, UGA; Rohitha, LPS; Abeysinghe, AMKB
    This research includes study of the relationship between Los Angeles Abrasion Value and the mineralogy of rock aggregates narrowed down to the commonly found high grade metamorphic rocks in Sabaragamuwa Province. The study was carried out minimizing the effect of other factors as much as possible. Los Angeles Abrasion Test and Mineral content of each rock sample selected was determined at the laboratory. Thin section analysis was carried out to determine the mineral content with the help of electronic microscope equipped with a digital camera and the AutoCAD software. Most of the rock quarries in the study area consist of biotite gneisses. Two samples are selected to represent them. Most of the other samples were selected from waste rock piles of quarries to have samples with varying content of minerals.The Regression Analysis was carried out to develop a relationship between Los Angeles Abrasion Value with engineering and mineralogical properties such as Relative Dry Density, Quartz Content, Feldspar Content as well as Mica Content. The best regression line fit for the test results is a third order polynomial line between Quartz Content and Los Angeles Abrasion Value which shows coefficient of determination as 0.7952. Another important achievement of this study was developing a field guide to assist the personnel at the field work. It was completed with the photograph of each rock sample , microscopic view of the sample and their respective engineering and mineralogical properties such as Los Angeles Abrasion Value, Dry Density, Quartz Content, Feldspar Content and Mica Content.