پیوندهای مفید
اخبار و اعلانات
آمار
| تعداد نشریات | 127 |
| تعداد شمارهها | 7,166 |
| تعداد مقالات | 77,030 |
| تعداد مشاهده مقاله | 155,812,414 |
| تعداد دریافت فایل اصل مقاله | 117,349,043 |
2.5D Inversion of Airborne Time Domain Electromagnetic Data through Constrained Occam and Conjugate Gradient Method to Image a Polymetallic Deposit | ||
| Geopersia | ||
| مقاله 10، دوره 16، شماره 1 - شماره پیاپی 22287825، فروردین 2026، صفحه 195-209 اصل مقاله (7.7 M) | ||
| نوع مقاله: Research Paper | ||
| شناسه دیجیتال (DOI): 10.22059/geope.2025.399987.648833 | ||
| نویسندگان | ||
| Ali Jafarabadi؛ Maysam Abedi* ؛ Ali Moradzadeh | ||
| School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran | ||
| چکیده | ||
| Porphyry deposits are major sources of copper, molybdenum, and gold. Airborne time-domain electromagnetic (TDEM) surveys play a crucial role in identifying conductive sulfide mineralization, particularly in geologically complex environments. This study employs 2.5D inversion of airborne TDEM data to image the Bell polymetallic deposit in British Columbia, Canada, offering improved accuracy over 1D methods in resolving complex geological structures, while maintaining lower computational demands than full 3D modeling. The methodology employs constrained Occam inversion with conjugate gradient optimization implemented in the ArjunGUI software. Forward modeling was conducted using finite-element methods in the wavenumber domain to simulate subsurface conductivity, and the results were subsequently transformed into time-domain using Fourier techniques.The inversion minimizes data misfit and model roughness using Lagrange multipliers and parameter bounds. Geological constraints, such as fixed background resistivities, were incorporated to ensure model accuracy. Inversion of an airborne TDEM survey line across the Bell deposit produced a resistivity model that highlights significant low-resistivity anomalies at approximately 100 m depth. These anomalies are associated with phyllic alteration zones and inferred fault structures that facilitated fluid circulation. High-resistivity areas delineate potassic alteration zones, which align with prior geophysical data and confirm the model's reliability. The 2.5D inversion provided enhanced accuracy compared to 1D methods and greater efficiency than 3D modeling, thereby facilitating targeted exploration in porphyry systems. The main limitations include high noise in late-time channels and potential mesh distortions due to topography. These limitations suggest that improvements in mesh discretization are needed for for future applications. Overall, this technique demonstrates the potential of 2.5D TDEM inversion as a practical and efficient approach for subsurface imaging and resource evaluation in polymetallic deposits. | ||
| کلیدواژهها | ||
| Airborne TDEM؛ 2.5D Inversion؛ Constrained Occam؛ Polymetallic Deposit؛ Porphyry Alteration | ||
| عنوان مقاله [English] | ||
| - | ||
| مراجع | ||
|
Abubakar, A., Habashy, T., Druskin, V., Knizhnerman, L., Alumbaugh, D., 2008. 2.5D forward and inverse modeling for interpreting low-frequency electromagnetic measurements. Geophysics 73: F165-F177. Auken, E., Boesen, T., Christiansen, A.V., 2017. A review of airborne electromagnetic methods with focus on geotechnical and hydrological applications from 2007 to 2017. In: Nielsen, L. (Ed.), Advances in Geophysics, 58: 47-93. Balch, S.J., Boyko, W.P., Paterson, N.R., 2003. The AeroTEM airborne electromagnetic system. The Leading Edge 22: 562-566. Box, M., 1966. A comparison of several current optimization methods, and the use of transformations in constrained problems. The Computer Journal 9: 67-77. Chang-Chun, Y., Xiu-Yan, R., Yun-He, L., Yan-Fu, Q., Chang-Kai, Q., Jing, C., 2015. Review on airborne electromagnetic inverse theory and applications. Geophysics 80: W17-W31. Constable, S.C., Parker, R.L., Constable, C.G., 1987. Occam’s inversion: A practical algorithm for generating smooth models from electromagnetic sounding data. Geophysics 52: 289-300. Dirom, G.E., Dittrick, M.P., McArthur, D.R., Ogryzlo, P.L., Pardoe, A.J., Stothart, P.G., 1995. Bell and Granisle porphyry copper-gold mines, Babine region, west-central British Columbia. In: Schroeter, T.G. (Ed.), Porphyry Deposits of the Northwestern Cordillera of North America, Vol. 46. Canadian Institute of Mining, Metallurgy and Petroleum, pp. 256-289. Ellis, R.G., 1998. Inversion of airborne electromagnetic data. Exploration Geophysics 29: 121-127. Engebretsen, K.W., Zhang, B., Fiandaca, G., Madsen, L.M., Auken, E., Christiansen, A.V., 2022. Accelerated 2.5D inversion of airborne transient electromagnetic data using reduced 3D meshing. Geophysical Journal International 230: 643-653. Everett, M.E., Edwards, R.N., 1993. Transient marine electromagnetics: The 2.5D forward problem. Geophysical Journal International 113: 545-561. Guo, Z., Xue, G., Liu, J., Wu, X., 2020. Electromagnetic methods for mineral exploration in China: A review. Ore Geology Reviews 118: 103357. Jafarabadi, A., 2025. Geophysical modeling of airborne time-domain electromagnetic and potential field data in the Bell polymetallic deposit: British Columbia, Canada. M.Eng. thesis, University of Tehran, College of Engineering, School of Mining Engineering. Ke, Z., Liu, L., Huang, L., Zhao, Z., Ji, Y., Liu, X., Fang, G., 2023. An efficient 2.5D forward algorithm based on the spectral element method for airborne transient electromagnetics data. Geophysical Prospecting 71: 1056-1069. Li, W.-B., Zeng, Z.-F., Li, J., Chen, X., Wang, K., Xia, Z., 2016. 2.5D forward modeling and inversion of frequency-domain airborne electromagnetic data. Applied Geophysics 13: 37-47. McMillan, M.S., Schwarzbach, C., Oldenburg, D.W., Haber, E., Holtham, E., Prikhodko, A., 2014. Recovering a thin dipping conductor with 3D electromagnetic inversion over the Caber deposit. SEG Technical Program Expanded Abstracts, SEG, pp. 180-184 Mitchinson, D.E.E., Enkin, R.J., Hart, C.J.R., 2013. Linking porphyry deposit geology to geophysics via physical properties: Adding value to Geoscience BC geophysical data. Geoscience BC Report, 116 pp. Núñez, P., Watts, T., Martin-Izard, A., Arias, D., Rubio, Á., Cortés, F., Díaz-Riopa, F., 2023. Airborne electromagnetic survey over the Touro copper VMS world-class deposit (NW Spain): Geological and geophysical correlation. Minerals 13: 17. Oldenburg, D., 1999. Applications of geophysical inversions in mineral exploration. SEG Technical Program Expanded Abstracts, Society of Explorayion Geophysicists. Oldenburg, D., Pratt, D.A., 2007. Geophysical inversion for mineral exploration: A decade of progress in theory and practice. Proceedings of Exploration 07: Fifth Decennial International Conference on Mineral Exploration, pp. 61-95. Oldenburg, D.W., Li, Y., Ellis, R.G., 1997. Inversion of geophysical data over a copper-gold porphyry deposit: A case history for Mt. Milligan. Geophysics 62: 1419-1431. Palacky, G.J., West, G.F., 1991. Airborne electromagnetic methods. In: Nabighian, M.N. (Ed.), Electromagnetic Methods in Applied Geophysics: Application, Parts A and B. Society of Exploration Geophysicists, 2: 811-880. Parker, R.L., 1994. Geophysical inverse theory, Vol. 1. Princeton University Press, 400 pp. Paterson, R., Silic, J., FitzGerald, D., 2016. Improved structural mapping and conductive targeting delivered by a new 2.5D AEM inversion solver. ASEG Extended Abstracts, 2016: 1-8. Pirttijärvi, M., 2014. ArjunGUI—2.5D modelling and inversion of time-domain EM data: User’s guide to version 1.0. Press, W.H., Teukolsky, S.A., Vetterling, W.T., Flannery, B.P., 2003. Numerical recipes in Fortran 77, Cambridge University Press, 1: 1010 pp. Raiche, A., Annetts, D., Sugeng, F., 2001. EM target response in complex hosts. ASEG Extended Abstracts, 2001: 1-4. Raiche, A., Sugeng, F., Annetts, D., 2003. Finding targets in complex hosts using airborne EM. ASEG Extended Abstracts, 2003: 1-4. Shah, A.K., Bedrosian, P.A., Anderson, E.D., Kelley, K.D., Lang, J., 2013. Integrated geophysical imaging of a concealed mineral deposit: A case study of the world-class Pebble porphyry deposit in southwestern Alaska. Geophysics 78: B317-B328. Silic, J., Paterson, R., FitzGerald, D., Archer, T., 2015. Comparing 1D and 2.5D AEM inversions in 3D geological mapping using a new adaptive inversion solver. In: 14th International Congress of the Brazilian Geophysical Society & EXPOGEF, Rio de Janeiro, Brazil, 3-6 August 2015, pp. 184-189. Sinclair, W.D., 2007. Porphyry deposits. In: Goodfellow, W.D. (Ed.), Mineral Deposits of Canada - A Synthesis of Major Deposit Types, District Metallogeny, the Evolution of Geological Provinces, and Exploration Methods, Special Publication 5. Geological Association of Canada, Mineral Deposits Division, pp. 223-243. Siripunvaraporn, W., 2012. Three-dimensional magnetotelluric inversion: An introductory guide for developers and users. Surveys in Geophysics 33: 5-27. Smith, R., 2014. Electromagnetic induction methods in mining geophysics from 2008 to 2012. Surveys in Geophysics 35: 123-156. Sugeng, F., Raiche, A., Rijo, L., 1993. Comparing the time-domain EM response of 2-D and elongated 3-D conductors excited by a rectangular loop source. Journal of Geomagnetism and Geoelectricity 45: 873-885. Unsworth, M., Travis, B., Chave, A., 1993. Electromagnetic induction by a finite electric dipole source over a 2-D Earth. Geophysics 58: 198-214. Walker, S.G., Doug, 2009. Report on a helicopter-borne AeroTEM system electromagnetic & magnetic survey (QUEST West Project). Wilson, G., Raiche, A., Sugeng, F., 2006. 2.5D inversion of airborne electromagnetic data. Exploration Geophysics 37: 363-371. Yu, W.W., Haber, E., 2012. A 2.5D inversion of airborne electromagnetic data. SEG International Exposition and Annual Meeting, Expanded Abstracts. Zhdanov, M.S., 2015. Inverse theory and applications in geophysics, 36: 730. | ||
|
آمار تعداد مشاهده مقاله: 356 تعداد دریافت فایل اصل مقاله: 110 |
||
سامانه مدیریت نشریات علمی. قدرت گرفته از سیناوب