The Lena West property near Lac des Bois, NT, held by Diamondex Resources Ltd., is an area of interest for exploration for kimberlitic features. In 2005, Frontier Geosciences Inc. was contracted to carry out seismic reflection and time-domain transient electromagnetic (TEM) surveys to investigate the possibility of kimberlite pipes being the cause of total magnetic intensity (TMI) anomalies previously identified on the property. One small part of the property, Area 1915, was surveyed with two perpendicular seismic reflection lines 1550 m and 1790 m long and three TEM lines consisting of six or seven individual soundings each with a 200 m transmitter loop. The results generated by Frontier Geosciences did not indicate any obvious vertical features that correlated with the TMI anomaly. The purpose of this study is to reprocess the seismic reflection data using different approaches than those of Frontier Geosciences and to invert the TEM data using a 1-D inversion code, EM1DTM recently developed by the UBC Geophysical Inversion Facility, to improve upon previous results and enhance the interpretation. A secondary objective is to test the robustness of EM1DTM when applied to observed TEM data, since prior to this study it had only been applied to synthetic data. Selective bandpass filtering, refraction and residual statics and f-x deconvolution procedures contributed to improved seismic images to the recorded two-way traveltime of 511.5 ms (approximately 1100 m depth). The TEM data were successfully inverted and converted to pseudo 2-D recovered resistivity sections that showed similar results to those from Frontier Geosciences. On the final seismic reflection sections, several strong reflectors are identified and the base of the overlying sedimentary layers is interpreted at a depth of ~600 m. The TEM results show consistent vertical structure with minimum horizontal variation across all lines to a valid depth of ~150 m. However, neither TEM nor seismic reflection results provide any information that correlates well with the observed TMI anomaly.

The Lena West property near Lac des Bois, NT, held by Diamondex Resources Ltd., is an area of interest for exploration for kimberlitic features. In 2005, Frontier Geosciences Inc. was contracted to carry out seismic reflection and time-domain transient electromagnetic (TEM) surveys to investigate the possibility of kimberlite pipes being the cause of total magnetic intensity (TMI) anomalies previously identified on the property. One small part of the property, Area 1915, was surveyed with two perpendicular seismic reflection lines 1550 m and 1790 m long and three TEM lines consisting of six or seven individual soundings each with a 200 m transmitter loop. The results generated by Frontier Geosciences did not indicate any obvious vertical features that correlated with the TMI anomaly. The purpose of this study is to reprocess the seismic reflection data using different approaches than those of Frontier Geosciences and to invert the TEM data using a 1-D inversion code, EM1DTM recently developed by the UBC Geophysical Inversion Facility, to improve upon previous results and enhance the interpretation. A secondary objective is to test the robustness of EM1DTM when applied to observed TEM data, since prior to this study it had only been applied to synthetic data. Selective bandpass filtering, refraction and residual statics and f-x deconvolution procedures contributed to improved seismic images to the recorded two-way traveltime of 511.5 ms (approximately 1100 m depth). The TEM data were successfully inverted and converted to pseudo 2-D recovered resistivity sections that showed similar results to those from Frontier Geosciences. On the final seismic reflection sections, several strong reflectors are identified and the base of the overlying sedimentary layers is interpreted at a depth of ~600 m. The TEM results show consistent vertical structure with minimum horizontal variation across all lines to a valid depth of ~150 m. However, neither TEM nor seismic reflection results provide any information that correlates well with the observed TMI anomaly.

The Lena West property near Lac des Bois, NT, held by Diamondex Resources Ltd., is an area of interest for exploration for kimberlitic features. In 2005, Frontier Geosciences Inc. was contracted to carry out seismic reflection and time-domain transient electromagnetic (TEM) surveys to investigate the possibility of kimberlite pipes being the cause of total magnetic intensity (TMI) anomalies previously identified on the property. One small part of the property, Area 1915, was surveyed with two perpendicular seismic reflection lines 1550 m and 1790 m long and three TEM lines consisting of six or seven individual soundings each with a 200 m transmitter loop. The results generated by Frontier Geosciences did not indicate any obvious vertical features that correlated with the TMI anomaly. The purpose of this study is to reprocess the seismic reflection data using different approaches than those of Frontier Geosciences and to invert the TEM data using a 1-D inversion code, EM1DTM recently developed by the UBC Geophysical Inversion Facility, to improve upon previous results and enhance the interpretation. A secondary objective is to test the robustness of EM1DTM when applied to observed TEM data, since prior to this study it had only been applied to synthetic data. Selective bandpass filtering, refraction and residual statics and f-x deconvolution procedures contributed to improved seismic images to the recorded two-way traveltime of 511.5 ms (approximately 1100 m depth). The TEM data were successfully inverted and converted to pseudo 2-D recovered resistivity sections that showed similar results to those from Frontier Geosciences. On the final seismic reflection sections, several strong reflectors are identified and the base of the overlying sedimentary layers is interpreted at a depth of ~600 m. The TEM results show consistent vertical structure with minimum horizontal variation across all lines to a valid depth of ~150 m. However, neither TEM nor seismic reflection results provide any information that correlates well with the observed TMI anomaly. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

As sondagens elétricas verticais (SEV) e as sondagens eletromagnéticas no domínio do tempo (TDEM) são muito usadas em estudos ambientais, hidrogeológicos e em exploração mineral. A interpretação desses dados feita individualmente com modelos unidimensionais normalmente acarreta em resultados ambíguos. Isso acontece devido ao fato de que cada metodologia enxerga a subsuperfície de uma forma diferente. No caso da SEV as estruturas resistivas são bem detectadas, já no caso da sondagem TDEM as estruturas condutivas é que são detectadas com melhor precisão. Outra diferença é a capacidade da SEV conseguir identificar melhor as estruturas rasas, por outro lado, as sondagens TDEM permitem investigar as estruturas mais profundas. Nesta pesquisa foram exploradas as potencialidades das SEVs e das sondagens TDEM, visando obter uma interpretação dos dados mais consistentes. Neste sentido foi desenvolvido um programa em Matlab para a inversão conjunta 1D de dados de SEV e TDEM, na qual explora \"o melhor\" de ambos os métodos. O algoritmo desenvolvido foi testado inicialmente com dados sintéticos e posteriormente foi empregado em dados reais adquiridos na bacia sedimentar do Paraná, na região de Bebedouro no Estado de São Paulo. O resultado final da inversão conjunta de dados de SEV/TDEM permitiu obter um modelo geoelétrico que mais se assemelha às condições geológicas reais, e cujas ambigüidades, que são inerentes ao processo de interpretação, foram minimizadas. Os resultados tanto com dados sintéticos quanto com dados reais foram são bastante promissores, mostram uma melhor recuperação dos meios modelados e um grande potencial de aplicações em estudos geocientíficos, em particular em estudos hidrogeológicos. / Electrical (DC) and transient electromagnetic (TEM) soundings have been used in a great number of environmental, hydrological and mining exploration studies. The data interpretation usually is done individually by 1D models resulting in ambiguous results. This fact can be explained by how the two different methodologies observe the medium below the surface. The vertical electrical sounding (VES) is good at marking very resistive structures, while the transient electromagnetic sounding (TEM) is very sensitive to map conductive structures. Another difference is that the VES detects better shallow structures, while the TEM soundings can reach deeper ones. In this research we explore the potentials of the both VES and TEM soundings, in order to obtain a more consistent interpretation of the data. In this way, a Matlab program for the joint inversion for DC and TEM soundings was developed aiming explore the best of the both methods. Initially, the algorithm was tested with synthetic data and after were used real data from Paraná Sedimentary Basin in Bebedouro region, São Paulo State. The geoelectrical model obtained from joint inversion of DC and TEM data are more similar to the real geological condition and the ambiguities were minimized. The results with synthetic and real data shows that the joint inversion of DC/TEM is better for recovering the simulated models and shows a great potential in geological studies, particularly in hidrogeological studies.

As sondagens elétricas verticais (SEV) e as sondagens eletromagnéticas no domínio do tempo (TDEM) são muito usadas em estudos ambientais, hidrogeológicos e em exploração mineral. A interpretação desses dados feita individualmente com modelos unidimensionais normalmente acarreta em resultados ambíguos. Isso acontece devido ao fato de que cada metodologia enxerga a subsuperfície de uma forma diferente. No caso da SEV as estruturas resistivas são bem detectadas, já no caso da sondagem TDEM as estruturas condutivas é que são detectadas com melhor precisão. Outra diferença é a capacidade da SEV conseguir identificar melhor as estruturas rasas, por outro lado, as sondagens TDEM permitem investigar as estruturas mais profundas. Nesta pesquisa foram exploradas as potencialidades das SEVs e das sondagens TDEM, visando obter uma interpretação dos dados mais consistentes. Neste sentido foi desenvolvido um programa em Matlab para a inversão conjunta 1D de dados de SEV e TDEM, na qual explora \"o melhor\" de ambos os métodos. O algoritmo desenvolvido foi testado inicialmente com dados sintéticos e posteriormente foi empregado em dados reais adquiridos na bacia sedimentar do Paraná, na região de Bebedouro no Estado de São Paulo. O resultado final da inversão conjunta de dados de SEV/TDEM permitiu obter um modelo geoelétrico que mais se assemelha às condições geológicas reais, e cujas ambigüidades, que são inerentes ao processo de interpretação, foram minimizadas. Os resultados tanto com dados sintéticos quanto com dados reais foram são bastante promissores, mostram uma melhor recuperação dos meios modelados e um grande potencial de aplicações em estudos geocientíficos, em particular em estudos hidrogeológicos. / Electrical (DC) and transient electromagnetic (TEM) soundings have been used in a great number of environmental, hydrological and mining exploration studies. The data interpretation usually is done individually by 1D models resulting in ambiguous results. This fact can be explained by how the two different methodologies observe the medium below the surface. The vertical electrical sounding (VES) is good at marking very resistive structures, while the transient electromagnetic sounding (TEM) is very sensitive to map conductive structures. Another difference is that the VES detects better shallow structures, while the TEM soundings can reach deeper ones. In this research we explore the potentials of the both VES and TEM soundings, in order to obtain a more consistent interpretation of the data. In this way, a Matlab program for the joint inversion for DC and TEM soundings was developed aiming explore the best of the both methods. Initially, the algorithm was tested with synthetic data and after were used real data from Paraná Sedimentary Basin in Bebedouro region, São Paulo State. The geoelectrical model obtained from joint inversion of DC and TEM data are more similar to the real geological condition and the ambiguities were minimized. The results with synthetic and real data shows that the joint inversion of DC/TEM is better for recovering the simulated models and shows a great potential in geological studies, particularly in hidrogeological studies.