Dyke detection as the main target of groundwater exploration using Magnetometry and Electromagnetic data

Articles in Press

Document Type : Research Paper

Authors

Department of Mining and Metallurgical Engineering, Yazd University, Yazd, Iran.

10.22059/ijmge.2024.367498.595117

Abstract

Dolerite structures such as dykes and sills are the main target for groundwater exploration in Karoo Supergroup area which is the main stratigraphy unit in South Africa. Morgenzon Farm is one of the sites in Karoo Supergroup, including a dolerite dyke, which is interested here. Magnetization/susceptibility and resistivity of dolerite dyke are significantly larger than those of encompassing sedimentary materials. Therefore, low induction number electromagnetic (EM-LIN) and magnetometry approaches may be useful to its detection. EM-LIN is composed of three techniques: EM38, EM31 and EM34, with the latter being manipulated. Since both EM34 and magnetometry inverse problems are linear, regularized weighted minimum length solution algorithm is utilized for their inverse modeling, but with one main discrepancy: model weighting function for magnetometry method is attained from multiplication of depth weighting and compactness constraints, while model weighting function is only equal to depth weighting for EM34 approach. Recovered susceptibility and conductivity sections derived respectively from magnetic and EM34 data sets show high consistency. Inverted models represent a dolerite dyke in the middle of the profile with depth range of 4 to 15m.

Keywords

Main Subjects

References

[1] Orlando, L., 2005. Joint interpretation of geophysical data for archaeology. A case study. Subsurface Sensing Technologies and Applications, 6(2), 235-250.
[2] Al Farajat, M. (2009). Characterization of a coastal aquifer basin using gravity and resistivity methods: a case study from Aqaba in Jordan. Acta Geophysica, 57(2), 454-475.
[3] Sultan, S. A., Santos, F. A. M., & Abbas, A. M. (2010). Joint inversion interpretation for gravity and resistivity data: a case study at New Heliopolis City, Cairo, Egypt. Near Surface Geophysics, 8(1), 43-53.
[4] Karavul, C., Dedebali, Z., Keskinsezer, A., Demirkol, A., 2010. Magnetic and electrical resistivity image survey in a buried Adramytteion ancient city in Western Anatolia, Turkey. International Journal of Physical Sciences, 5(6), 876-883.
[5] Gambetta, M., Armadillo, E., Carmisciano, C., Stefanelli, P., Cocchi, L., & Tontini, F. C. (2011). Determining geophysical properties of a near-surface cave through integrated microgravity vertical gradient and electrical resistivity tomography measurements. Journal of cave and karst studies, 73(1), 11-15.
[6] Zhang, G., Lu, Q.T., Zhang, G.B., 2018. Joint Interpretation of Geological, Magnetic, AMT, and ERT Data for Mineral Exploration in the Northeast of Inner Mongolia, China. Pure and Applied Geophysics, 175(3), 989-1002.
[7] Ebrahimi, A., Dehghan, M. J., & Ashtari, A. (2019). Contribution of gravity and Bristow methods for Karez (aqueduct) detection. Journal of Applied Geophysics, 161, 37-44.
[8] Ghanati R., Ghari, H.A., Mirzaei M., Hafizi M.K. (2015). Nonlinear inverse modeling of magnetic anomalies due to thin sheets and cylinders using Occam’s method. In: 8th congress of the Balkan geophysical society, Chania, Greece. doi: https://doi.org/10.3997/2214-4609.201414178
[9] Urban, T.M., Rasic, J.T., Alix, C., Anderson, D.D., Chisholm, L., Jacob, R.W., Manning, S.W., Mason, O.K., Tremayne, A.H. & Vinson, D. (2019). Magnetic detection of archaeological hearths in Alaska: A tool for investigating the full span of human presence at the gateway to North America. Quaternary Science Reviews, 211, 73-92. doi: https://doi.org/10.1016/j.quascirev.2019.03.018.
[10] Al-Farhan, M., Oskooi, B., Ardestani, V. E., Abedi, M., & Al-Khalidy, A. (2019). Magnetic and gravity signatures of the Kifl oil field in Iraq. Journal of Petroleum Science and Engineering, 183, 106397. doi: https://doi.org/10.1016/j.petrol.2019.106397.
[11] Fedi, M., La Manna, M., & Palmieri, F. (2003). Nonstationary analysis of geomagnetic time sequences from Mount Etna and North Palm Springs earthquake. Journal of Geophysical Research: Solid Earth, 108 (B10). doi: https://doi.org/10.1029/2001JB000820.
[12] Caratori Tontini, F., De Ronde, C. E. J., Yoerger, D., Kinsey, J., & Tivey, M. (2012). 3‐D focused inversion of near‐seafloor magnetic data with application to the Brothers volcano hydrothermal system, Southern Pacific Ocean, New Zealand. Journal of Geophysical Research: Solid Earth, 117(B10). doi: https://doi.org/10.1029/2012JB009349
[13] Al-Garni, M. (2011). Magnetic and DC resistivity investigation for groundwater in a complex subsurface terrain. Arabian Journal of Geosciences, volume, 4, 385–400. doi: https://doi.org/10.1007/s12517-009-0071-z.
[14] Ghari, H., Varfinezhad, R., & Parnow, S. (2023). 3D joint interpretation of potential field, geology, and well data to evaluate a salt dome in the Qarah‐Aghaje area, Zanjan, NW Iran. Near Surface Geophysics, 21(3), 233-246. doi: https://doi.org/10.1002/nsg.12252.
[15] Fedi, M. (2007). DEXP: A fast method to determine the depth and the structural index of potential fields sources. Geophysics, 72 (1), I1-I11. doi: https://doi.org/10.1190/1.2399452.
[16] Fedi, M., & Pilkington, M. (2012). Understanding imaging methods for potential field data. Geophysics, 77 (1), G13-G24. doi: https://doi.org/10.1190/geo2011-0078.1.
[17] Mehrvash, M., Abedi, M., Norouzi, G. H. (2023). A potential field geophysical study to image a Potash resource through Depth from Extreme Points, Ghareh-Aghaj deposit in NW of Iran. International Journal of Mining and Geo-Engineering, 57(3), 241-250. doi: https://doi.org/10.22059/ijmge.2023.354047.595024.
[18] Pilkington, M. (2009). 3D magnetic data-space inversion with sparseness constraints. Geophysics, 74(1), L7-L15. doi: https://doi.org/10.1190/1.3026538.
[19] Cella, F., & Fedi, M. (2012). Inversion of potential field data using the structural index as weighting function rate decay. Geophysical Prospecting, 60 (2), 313-336. doi: https://doi.org/10.1111/j.1365-2478.2011.00974.x.
[20] Parnow, S., Oskooi, B., & Florio, G. (2021). Improved linear inversion of low induction number electromagnetic data. Geophysical Journal International, 224(3), 1505-1522. doi: https://doi.org/10.1093/gji/ggaa531
[21] Pérez-Flores, M. A., Antonio-Carpio, R. G., Gómez-Treviño, E., Ferguson, I., & Méndez-Delgado, S. (2012). Imaging of 3D electromagnetic data at low-induction numbers. Geophysics, 77(4), WB47-WB57. doi: https://doi.org/10.1190/geo2011-0368.1
[22] Ghari, H., & Varfinezhad, R. (2022). 2D Linear inversion of ground-based controlled-source electromagnetic data under a low induction number condition. Journal of the Earth and Space Physics, 48(3), 557-573. doi: https://doi.org/10.22059/jesphys.2022.334600.1007385.
[23] Varfinezhad, R., & Parnow, S. (2022). 3D Electromagnetic low induction number modeling using integral equations. Journal of the Earth and Space Physics, 47 (4), 99-110. doi: https://doi.org/10.22059/jesphys.2021.325291.1007330.
[24] McNeill, J. D. (1980). Electromagnetic terrain conductivity measurement at low induction numbers.
[25] Gallardo, L.A. (2004). Joint two-dimensional inversion of geoelectromagnetic and seismic refraction data with cross-gradients constraint (Doctoral dissertation, University of Lancaster).
[26] Pérez-Flores, M. A., Méndez-Delgado, S., & Gómez-Treviño, E. (2001). Imaging low-frequency and dc electromagnetic fields using a simple linear approximation. Geophysics, 66(4), 1067-1081. Doi: https://doi.org/10.1190/1.1487054.
[27] Tikhonov, A. N., & Arsenin, V. I. A. K. (1977). Solutions of ill-posed problems.
[28] Li, Y., & Oldenburg, D. W. (1996). 3-D inversion of magnetic data. Geophysics, 61(2), 394-408. doi: https://doi.org/10.1190/1.1443968
[29] Last, B. J., & Kubik, K. (1983). Compact gravity inversion. Geophysics, 48(6), 713-721. doi: https://doi.org/10.1190/1.1441501.
[30] Makhokha, D., & Fourie, F. (2016). A systematic approach to the interpretation of conductivity anomalies across intrusive dolerite dykes and sills in the Karoo Supergroup (Doctoral dissertation, MSc thesis. University of the Free State, Bloemfontein).
[31] Geel, C., 2014. Brief geologic overview of the Cape Fold Belt and Karoo Basin: Field excursion to Matjiesfontein, 10th Inkaba yeAfrica conference. Matjiesfontein, Inkba yeAfrica.
[32] Duncan, R. A., Hooper, P. R., Rehacek, J., Marsh, J., & Duncan, A. R. (1997). The timing and duration of the Karoo igneous event, southern Gondwana. Journal of Geophysical Research: Solid Earth, 102(B8), 18127-18138. doi: https://doi.org/10.1029/97JB00972.
[33] Athanasiou, E. N., Tsourlos, P. I., Papazachos, C. B., & Tsokas, G. N. (2007). Combined weighted inversion of electrical resistivity data arising from different array types. Journal of applied geophysics, 62(2), 124-140. doi: https://doi.org/10.1016/j.jappgeo.2006.09.003.
[34] De Kock, M.O., Beukes, N.J., Götz, A.E., Cole, D., Robey, K., Birch, A., Withers, A. & Van Niekerk, H.S. (2016). Open file progress report on exploration of the Southern Karoo Basin through CIMERAKARIN borehole KZF-1 in the Tankwa Karoo, Witzenberg (Ceres) district. DST-NRF Centre of Excellence for Integrated Mineral and Energy Resources Analysis (CIMERA), University of Johannesburg, South Africa.
[35] Blakely, R. J. (1996). Potential theory in gravity and magnetic applications. Cambridge university press.
[36] Vatankhah, S., Ardestani, V. E., & Renaut, R. A. (2014). Automatic estimation of the regularization parameter in 2D focusing gravity inversion: application of the method to the Safo manganese mine in the northwest of Iran. Journal of Geophysics and Engineering, 11(4), 045001. https://doi.org/10.1088/1742-2132/11/4/045001
International Journal of Mining and Geo-Engineering

Articles in Press, Accepted Manuscript
Available Online from 24 January 2024

Files

Share

How to cite

Statistics