Passive airborne EM and ground IP\resistivity results over the Romero intermediate sulphidation epithermal gold deposits, Dominican Republic*
Jean M. Legault 1 4 Jeremy Niemi 2 Jeremy S. Brett 3 Shengkai Zhao 1 Zihao Han 1 Geoffrey C. Plastow 11 Geotech Ltd, 245 Industrial Parkway North, Aurora, Ontario, Canada L4G 4C4.
2 GoldQuest Mining Corporation, Suite 501 – 133 Richmond Street West, Toronto, Ontario, Canada M5H 2 L3.
3 MPH Consulting Limited, Suite 501 – 133 Richmond Street West, Toronto, Ontario, Canada M5H 2 L3.
4 Corresponding author. Email: jean@geotech.ca
Exploration Geophysics 47(3) 191-200 https://doi.org/10.1071/EG15089
Submitted: 1 September 2015 Accepted: 18 February 2016 Published: 14 April 2016
Abstract
The Romero gold-copper-zinc-silver deposits are located in the Province of San Juan, Dominican Republic, ~165 km west-north-west of Santo Domingo. Romero and Romero South orebodies contain stratabound gold mineralisation with copper, silver and zinc of intermediate sulphidation (IS), epithermal style. The gold mineralisation is associated with disseminated to semi-massive sulphides, sulphide veinlets and quartz-sulphide veins within quartz-pyrite, quartz-illite-pyrite and illite-chlorite-pyrite alteration.
Ground direct current (DC) resistivity and induced polarisation (IP) supported by ground magnetics remain the preferred geophysical targeting tools for drill follow-up along with geologic mapping and geochemistry. However, Z-axis tipper electromagnetics (ZTEM) passive airborne electromagnetics (AEM) and magnetics have recently also been applied with success for reconnaissance mapping of deep alteration and fault structures regionally.
The airborne ZTEM-magnetic surveys, supported by three-dimensional (3D) inversions, show good correlation with the ground IP\resistivity surveys in the Romero and Romero South gold-copper-zinc-silver IS deposit area. The results have provided targets for ground follow-up and deep targeted drilling, and were successful in identifying a previously unknown deep (>500 m) continuity between the Romero and Romero South deposits.
Key words: airborne electromagnetics, case history, epithermal, gold, induced polarisation, inversion, ZTEM.
References
de Lugao, P. P., and Wannamaker, P. E., 1996, Calculating the two-dimensional magnetotelluric Jacobian in finite elements using reciprocity: Geophysical Journal International, 127, 806–810| Calculating the two-dimensional magnetotelluric Jacobian in finite elements using reciprocity:Crossref | GoogleScholarGoogle Scholar |
Edwards, L. S., 1977, A modified pseudo section from resistivity and IP: Geophysics, 42, 1020–1036
| A modified pseudo section from resistivity and IP:Crossref | GoogleScholarGoogle Scholar |
Hennessey, B. T., San Martin, A. J., Gowans, R. M., Dreesbach, C., and Jacobs, C., 2014, Preliminary economic assessment (PEA) for the Romero project, Tireo property, Province of San Juan, Dominican Republic: NI 43–101 Technical Report for GoldQuest Mining Corp. by Micon International Ltd, 233 pp.
Hermance, J. F., and Thayer, R. E., 1975, The telluric-magnetotelluric method: Geophysics, 37, 349–364
Holtham, E., and Oldenburg, D. W., 2008, Three-dimensional forward modelling and inversion of Z-TEM data: 78th Annual International Meeting, SEG, Expanded Abstracts, 564–568.
Holtham, E., and Oldenburg, D., 2010, Three-dimensional inversion of MT and ZTEM data: 81st Annual International Meeting, SEG, Expanded Abstracts, 29, 655–659.
Hoschke, T., 2011, Geophysical signatures of copper-gold porphyry and epithermal gold deposits, and implications for exploration: CODES-ARC Center of Excellence in Ore Deposits, University of Tasmania.
Hubert, J., Lee, B., Unsworth, M., Richards, J., Oldenburg, D., and Cheng, L. Z., 2013, Imaging a Ag-Au rich epithermal system in British Columbia, Canada, with airborne ZTEM and ground magnetotelluric data: SEG Technical Program, Expanded Abstracts, 1606–1610.
Irvine, R. J., and Smith, M. J., 1990, Geophysical exploration for epithermal gold deposits: Journal of Geochemical Exploration, 36, 375–412
| Geophysical exploration for epithermal gold deposits:Crossref | GoogleScholarGoogle Scholar |
Labson, V. F., Becker, A., Morrison, H. F., and Conti, U., 1985, Geophysical exploration with audio-frequency natural magnetic fields: Geophysics, 50, 656–664
| Geophysical exploration with audio-frequency natural magnetic fields:Crossref | GoogleScholarGoogle Scholar |
Legault, J. M., and Wannamaker, P. E., 2014, Two-dimensional joint inversion of ZTEM and MT plane-wave EM data for near surface applications: SAGEEP, Expanded Abstracts, 18–23.
Legault, J. M., Wilson, G., Gribenko, A., Zhdanov, M. S., Zhao, S., and Fisk, K., 2012a, An overview of the ZTEM and AirMt airborne electromagnetic systems – a case study from the Nebo-Babel Ni-Cu-PGE deposit, West Musgrave, Western Australia: Preview, 158, 26–32
Legault, J. M., Zhao, S., and Fitch, R., 2012b, ZTEM airborne AFMAG survey results over low sulphidation epithermal gold-silver vein systems at Gold Springs, south eastern Nevada: 22nd International Geophysical Conference and Exhibition, ASEG, Extended Abstracts, 1–4
Legault, J. M., Zhao, S., Bournas, N., Plastow, G., and Kearvell, G., 2014, Helicopter AFMAG (ZTEM) and aeromagnetic survey results over epithermal gold and gold-skarn deposits in the Guerrero Gold Belt, Mexico: SEG Technical Program, Expanded Abstracts, 1800–1804.
Legault, J. M., Kwan, K., and Prikhodko, A., 2015a, Airborne EM in exploring for epithermal gold and gold skarn deposits: Three examples from the Great Basin and Western Cordillera, in W. M. Pennell, and L. J. Garside, eds., New concepts and discoveries: Geological Society of Nevada symposium proceedings, 1, 101–125.
Legault, J. M., Niemi, J., Brett, J., Zhao, S., Han, Z., and Plastow, G., 2015b, Passive airborne EM and ground IP\resistivity results over the Romero intermediate sulphidation epithermal gold deposits, Dominican Republic: ASEG-PESA, Extended Abstracts, 1–5.
Li, Y., and Oldenburg, D. W., 1996, 3-D inversion of magnetic data: Geophysics, 61, 394–408
| 3-D inversion of magnetic data:Crossref | GoogleScholarGoogle Scholar |
Lo, B., and M. Zang, 2008, Numerical modeling of Z-TEM (airborne AFMAG) responses to guide exploration strategies: 78th Annual International Meeting, SEG, Expanded Abstracts, 1098–1101.
McNeill, J. D., and Labson, V. F., 1991, Geological mapping using VLF radio fields, in M. N. Nabighian, ed., Electromagnetic methods in applied geophysics, volume 2 – applications, parts A and B: Society of Exploration Geophysicists, 521–640.
Niemi, J., 2014, Developing resources in and above the ground – gold and copper development in the Dominican Republic: GoldQuest corporate presentation, June 2014. Available at www.goldquestcorp.com.
Oldenburg, D. W., and Li, Y., 1994, Inversion of induced polarization data: Geophysics, 59, 1327–1341
| Inversion of induced polarization data:Crossref | GoogleScholarGoogle Scholar |
Pedersen, L. B., 1998, Tensor VLF measurements: our first experiences: Exploration Geophysics, 29, 52–57
| Tensor VLF measurements: our first experiences:Crossref | GoogleScholarGoogle Scholar |
Sasaki, Y., Yi, M.-J., and Choi, J., 2013, 3D inversion of ZTEM data for uranium exploration: 23rd International Geophysical Conference and Exhibition, ASEG, Extended Abstracts, 1–4.
Sattel, D., and Witherly, K., 2012, The modeling of ZTEM data with 2D and 3D algorithms: 82nd Annual International Meeting, SEG, Expanded Abstracts, 1–5.
Silitoe, R. H. 2013, Comments on geology and exploration of the Romero gold-copper prospect and environs, Las Tres Palmas Project, Dominican Republic: Report for GoldQuest Mining Corp., 9 pp.
Spies, B., 1989, Depth of investigation in electromagnetic sounding methods: Geophysics, 54, 872–888
| Depth of investigation in electromagnetic sounding methods:Crossref | GoogleScholarGoogle Scholar |
Stodt, J. A., Hohmann, G. W., and Ting, S. C., 1981, The telluric-magnetotelluric method in two- and three-dimensional environments: Geophysics, 46, 1137–1147
| The telluric-magnetotelluric method in two- and three-dimensional environments:Crossref | GoogleScholarGoogle Scholar |
Tarantola, A., 1987, Inverse problem theory: Elsevier.
Taylor, B. E., 2007, Epithermal gold deposits, in W. D. Goodfellow, ed., Mineral deposits of Canada: a synthesis of major deposit-types, district metallogeny, the evolution of geological provinces, and exploration methods: Geological Association of Canada, Mineral Deposits Division, Special Publication No. 5, 113–139.
Telford, W. M., Geldart, L. P., and Sheriff, R. E., 1990, Applied geophysics (2nd edition): Cambridge University Press.
Vozoff, K., 1972, The magnetotelluric method in the exploration of sedimentary basins: Geophysics, 37, 98–141
| The magnetotelluric method in the exploration of sedimentary basins:Crossref | GoogleScholarGoogle Scholar |
Wannamaker, P. E., Stodt, J. A., and Rijo, L., 1987, A stable finite element solution for two-dimensional magnetotelluric modeling: Geophysical Journal of the Royal Astronomical Society, 88, 277–296
| A stable finite element solution for two-dimensional magnetotelluric modeling:Crossref | GoogleScholarGoogle Scholar |
Ward, S. H., 1959, AFMAG - airborne and ground: Geophysics, 24, 761–787
| AFMAG - airborne and ground:Crossref | GoogleScholarGoogle Scholar |