ISERME - 2019

Permanent URI for this collectionhttp://192.248.9.226/handle/123/14735

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Browsing ISERME - 2019 by Author "Abeysinghe, AMKB"

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    item: Conference-Full-text
    Appraisal of electrode configuration characteristics in resistivity surveying
    (Department of Earth Resources Engineering, 2019-08) Kankanamge, BU; Chathuranga, SMS; Ruwanika, ILD; Palamure, PK; Abeysinghe, AMKB; Samaradivakara, GVI; Jayawardena, CL; Dissanayake, DMDOK; Samaradivakara, GVI
    Non-destructive subsurface exploration methods could reveal subterranean characteristics with minimal consumption of time and resources. However, validity of such interpretations could vary depending on the appropriate use of the controllable parameters in the geophysical method, with respect to the subsurface complexities. Accordingly, this study evaluates the sub subsurface characteristics of several locations revealed by the interpretation of resistivity data to understand the performance of different electrode configurations used in resistivity surveying. The electrode spacings maintained at each configuration was also critically assessed to identify the most appropriate for a particular instance of surveying. Furthermore, subsurface profiles were computed using three different interpretation methods to identify any influences from the interpretation method on the accuracy of the resultant profile. The results reveal a strong dependency of interpretations on the array configuration and maintained electrode spacing. And it was determined a suitable electrode spacing for improved subsurface interpretation. In order to improve accuracy of interpretations, it also suggests the need of developing an upper limit for current electrode spacing (AB) of the Schlumberger Array Configuration, given the general electrode spacing is maintaining a lower limit as AB > 5 (potential electrode spacing).
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    item: Conference-Abstract
    Exploration of potential sources for extraction of rare earth elements (REEs) in Sri Lanka
    (Department of Earth Resources Engineering, 2019-08) Dushyantha, NP; Batapola, NM; Premasiri, HMR; Abeysinghe, AMKB; Rohitha, LPS; Ratnayake, NP; Dissanayake, DMDOK; Ilankoon, IMSK; Dissanayake, DMDOK; Samaradivakara, GVI
    Rare Earth Elements (REEs) are a set of seventeen chemically similar elements in the periodic table, including fifteen metallic elements of the lanthanide series. Yttrium and Scandium. REEs are significantly used in numerous high-tech applications in sectors, such as metallurgy, military, petroleum and agriculture. Therefore, REEs are considered as critical and strategic elements i n the industrial revolution towards a green economy i n the future. However, China is the world's largest producer, consumer and exporter of REEs, currently controlling more than 90% of the global supply. According to the recent Chinese industrial policies, they have reduced their REEs export in 2010 in order to build up a REEs stockpile for future domestic uses. As a result, currently, REEs supply is at a risk of disrupting i n the world market, which has created many concerns among REEs stakeholders. Thus, worldwide explorations for REEs are carried out to prospect new potential sources. In this context, Sri Lanka is a country, which has geological settings implying the presence of probable primary REEs sources (e.g. apatite in carbonatites, granitic and synitic pegmatites, granitic rocks and hydrothermal veins) and secondary REEs sources (e.g. mineral sand, gem gravel, stream sediments, clay deposits and laterite deposits). According to previous studies in Sri Lanka, considerable contents of REEs have already been identified in a few locations of the country, such as well-known monazite deposit in Pulmoddai containing Cerium (28%), Lanthanum (15%), Neodymium (10%), Promethium (3%), Samarium (2%), Gadolinium (2%) and Yttrium (1%).Therefore, aforesaid potential sources will be explored as a worthwhile approach to address the impending REEs problems i n both local and global context. However, available resources on land w i l l not be enough to cater the future demand, and therefore, offshore sources, including upwelling areas in southern coast of Sri Lanka are also needed to be investigated as a promising solution for future REEs scarcity. However, effectiveness of extraction of REEs depends on the quality of the resources and the degree to which the resources have been explored. Based on the REE concentrations in aforesaid sources, novel extraction technologies will be developed to get the maximum benefits to the Sri Lankan mineral industry and ultimately to the national economy of the country.
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    Identification of ground subsidence due to collapse of solution cavities in marble rock
    (Department of Earth Resources Engineering, 2019-08) Senadheera, PK; Attanayake, AMGB; Dharmasena, ASL; Sudusingha, SKMN; Jayawardena, CL; Abeysinghe, AMKB; Dissanayake, DMDOK; Samaradivakara, GVI
    Ground subsidence can occur due to reasons such as; oil/gas/water extraction, mining, and dissolution of carbonate rocks. Identification of potential subsidence locations are usually difficult due to limited information and complexities in the subsurface profile. This research focuses on the ground subsidence occurring due to the collapse of solution cavities in marble rocks. Accordingly, two locations in Matale and Badulla districts which had previously encountered subsidence in the marble rock band of the Highland Complex were surveyed using Ground Penetrating Radar (GPR) to generate cavity profiles of 2D trace analysis of the radargrams. The GPR interpretations were validated using the well-log data and the records on the previous ground subsidence reports. Several GPR surveys conducted in Matale region indicated the presence of solution cavities in marble rock. The increasing number of cavities towards the river in the region can be considered as the influence of the groundwater movements on cavity formation. The resultant cavity profiles of T01-T02 were compatible with available well-log data (MA 182) and indicated that the accuracy of subsurface details that can be gathered using GPR technology. Similar conditions were observed in the Badulla area and showed the evidence of groundwater induced solution cavities in marble rock. Hence, to minimize the ground subsidence hazards, it is recommended to conduct GPR surveys to obtain subsurface information, prior to future construction or development activities on the regions where marble bearing bedrock is present.