1887
Volume 54, Issue 6
  • ISSN: 0812-3985
  • E-ISSN: 1834-7533

Abstract

Modelling and analysis of helicopter electromagnetic data result in resistivity and susceptibility models and derivatives of magnetic data that characterise shallow parts of the Stillwater Complex, critical for aiding exploration and expansion of globally scarce critical and battery mineral resources that include platinum group elements, nickel, copper and chromium. The magnetic susceptibly models derived from the electromagnetic data and the tilt derivative of the magnetic data image layering, mafic dikes, banded iron formation, and serpentinised peridotite. Known areas with contact-type mineralisation are generally characterised by low resistivities and susceptibilities where the volume of mineralised rock is large and/or the depth is shallow. We use iso-cluster and edge detection analysis of both resistivities and susceptibilities to identify potential mineralisation in poorly characterised regions as well as faults. Low resistivity layers beneath large landslides reflect water saturated porous slip surfaces which can interfere with drilling. This uncommon approach of tightly linking the resistivity and susceptibility models and magnetic anomaly data to rock property, surficial geologic, drill hole and soil geochemistry data to image the geology in the upper ∼100 m, aids identification of prospective mineralised regions as well landslides and faults that can impact mineral exploration and local hazards.

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References

  1. Bader, J.W.2019. Structural inheritance and the role of basement anisotropies in the laramide structural and tectonic evolution of the North American Cordilleran foreland, Wyoming. Lithosphere11 no. 1: 129–148.
     [Google Scholar]
  2. Balch, S.J.2005. The geophysical signatures of platinumgroup element deposits. Exploration for platinum-group element deposits. Mineralogical Association of Canada, Short-Course Series, 35, 275–286.
  3. Baranov, V., and H.Naudy. 1964. Numerical calculation of the formula of reduction to the magnetic pole. Geophysics29: 67–79.
     [Google Scholar]
  4. Barnes, S., P.Pagé, H.M.Prichard, M.L.Zientek, and P.C.Fisher. 2015. Chalcophile and platinum-group element distribution in the ultramafic series of the Stillwater Complex, MT, USA—implications for processes enriching chromite layers in Os, Ir, Ru, and Rh. Mineralium Deposita51 no. 1: 25–47.
     [Google Scholar]
  5. Barnes, S., P.Pagé, and M.L.Zientek. 2020. The lower banded series of the Stillwater Complex, Montana: whole-rock lithophile, chalcophile and platinum-group element distributions. Mineralium Deposita55: 163–186.
     [Google Scholar]
  6. Baroň, I., R.Supper, E.Winkler, K.Motschka, A.Ahl, M.Čarman, and ŠKumelj. 2013. Airborne geophysical survey of the catastrophic landslide at Stože, Log pod Mangrtom, as a test of an innovative approach for landslide mapping in steep alpine terrains. Natural Hazards and Earth System Sciences13 no. 10: 2543–2550.
     [Google Scholar]
  7. Bergh, H.W.1970. Paleomagnetism of the Stillwater Complex, Montana. In Paleogeophysics, ed. S.K.Runcorn, 143–158. San Diego, CA: Academic.
     [Google Scholar]
  8. Bevan, A.1925. Rocky mountain peneplains northeast of Yellowstone park. Journal of Geology23: 563–587.
     [Google Scholar]
  9. Blakely, R.J., and M.L.Zientek. 1985. Magnetic anomalies over a mafic intrusion: The stillwater complex. In The stillwater complex, Montana: geology and guide, eds. G.K.Czamanske, and M.LZientek, 39–45. Billings: Montana Bureau of Mines and Geology Special Publication.
     [Google Scholar]
  10. Bloss, B.R., C.A.Finn, M.L.Zientek, and B.J.Minsley. 2014. Old data, New tricks: New insights into the Stillwater Complex, 2014 Fall Meeting, AGU, 15–19 December, San Francisco, CA.
  11. Bolle, O., H.Diot, W.Fransen, and M.D.Higgins. 2021. Central sagging of a giant mafic intrusion: The ediacaran sept Îles layered intrusion (Québec, Canada). Journal of the Geological Society178 no. 1: 2020–2029.
     [Google Scholar]
  12. Boudreau, A.E., K.C.Butak, E.P.Geraghty, P.A.Holick, and M.S.Koski. 2020. Mineral deposits of the Stillwater Complex, Geology of Montana, Vol. II, Geologic Special topics. Montana Bureau of Mines and Geology Special Publication, 33.
  13. Boudreau, A.E., and I.McCallum. 1986. Investigations of the Stillwater Complex; III, The picket Pin Pt/Pd deposit. Economic Geology81 no. 8: 1953–1975.
     [Google Scholar]
  14. Carlson, R.R., W.Z.Savage, and K.Segerstrom. 1977. Large-scale gravitational spreading of mountain ridges in the Stillwater Complex of Montana. U.S. Geological Survey Professional Paper1050: 235.
     [Google Scholar]
  15. Childs, J.F., and A.Armitage. 2021. Technical report on the 2021 mineral resource estimates for the Stillwater West PGE-Ni-Cu-Co + Au Project, Montana, USA [NI-43-101 technical report]; prepared by Childs Geoscience Inc. Group Ten Metals Inc., 1–221.
  16. Cole, J., C.A.Finn, and S.J.Webb. 2013. Overview of the magnetic signatures of the palaeoproterozoic rustenburg layered suite, bushveld complex, South Africa. Precambrian Research236: 193–213.
     [Google Scholar]
  17. Cooper, R.W.1997. Magmatic unconformities and stratigraphic relations in the peridotite zone, stillwater complex, Montana. Canadian Journal of Earth Sciences34: 407–425.
     [Google Scholar]
  18. Corson, S.R., J.F.Childs, J.P.Dahy, D.W.Keith, M.S.Koski, and L.W.Leroy. 2002. The Reef Package stratigraphy that contains the J-M Platinum-Palladium Reef of the Stillwater Complex, Montana. The 9th International Platinum Symposium, Abstract with Program, Billings, Montana, 101–102.
  19. Day, W.C.2020. Technical overview of the US Geological Survey Earth Mapping Resources Initiative (Earth MRI). Fact Sheet(2020-3055).
  20. Farquharson, C.G., D.W.Oldenburg, and P.S.Routh. 2003. Simultaneous 1D inversion of loop–loop electromagnetic data for magnetic susceptibility and electrical conductivity. Geophysics68 no. 6: 1857–1869.
     [Google Scholar]
  21. Ferré, E.C., S.M.Maes, and K.C.Butak. 2009. The magnetic stratification of layered mafic intrusions: natural examples and numerical models. Lithos111 no. 1-2: 83–94.
     [Google Scholar]
  22. Finn, C.A., P.A.Bedrosian, J.C.Cole, T.D.Khoza, and S.J.Webb. 2015. Mapping the 3D extent of the Northern Lobe of the Bushveld layered mafic intrusion from geophysical data. Precambrian Research268: 279–294.
     [Google Scholar]
  23. Finn, C.A., P.A.Bedrosian, W.S.Holbrook, E.Auken, B.R.Bloss, and J.Crosbie. 2022. Geophysical imaging of the Yellowstone hydrothermal plumbing system. Nature603 no. 7902: 643–647.
     [Google Scholar]
  24. Finn, C.A., M.Deszcz-Pan, E.D.Anderson, and D.A.John. 2007. Three-dimensional geophysical mapping of rock alteration and water content at Mount Adams, Washington: implications for lahar hazards. Journal of Geophysical Research112 no. B10204. doi:10.1029/2006JB004783.
     https://doi.org/10.1029/2006JB004783 [Google Scholar]
  25. Finn, C.A., M.Deszcz-Pan, J.L.Ball, B.J.Bloss, and B.J.Minsley. 2018. Three-dimensional geophysical mapping of shallow water saturated altered rocks at Mount Baker, Washington: implications for slope stability. Journal of Volcanology and Geothermal Research357: 261–275.
     [Google Scholar]
  26. Finn, C.A., M.L.Zientek, H.L.Parks, and D.E.Peterson. 2020. Mapping the 3D extent of the Stillwater Complex, Montana—implications for potential platinum group element exploration and development. Precambrian Research348: 105860.
     [Google Scholar]
  27. Foose, R., D.U.Wise, and G.S.Garbarini. 1961. Structural geology of the Beartooth Mountains, Montana and Wyoming. Geological Society of America Bulletin72 no. 8: 1143–1172.
     [Google Scholar]
  28. Geissman, J.W., and D.W.Mogk. 1986. “Late Archean tectonic emplacement of the Stillwater Complex along reactivated basement structures, northern Beartooth Mountains, southern Montana, U.S.A.” Proceedings of the 6th International Conference on Basement Tectonics: 25–44.
  29. Geraghty, E.P.2013. Geologic map of the Stillwater Complex within the Beartooth Mountains front laramide triangle zone, south-central Montana. Montana Bureau of Mines and Geology Open-File Report645: 21pp. and 1:48000 scale map.
     [Google Scholar]
  30. Green, T., and D.Peck2005. Platinum group elements exploration: Economic considerations and geological criteria. Mineralogical Association of Canada Short Course35: 247–274.
     [Google Scholar]
  31. Howard, D.2020. Geological survey of Western Australia: AusAEM20-WA project. Preview2020 no. 205: 18–18.
     [Google Scholar]
  32. Ivanic, T.J., O.Nebel, J.Brett, and R.E.Murdie. 2018. The Windimurra Igneous Complex: an Archean Bushveld?Geological Society, London, Special Publications453 no. 1: 313–348.
     [Google Scholar]
  33. Jackson, E.D.1961. Primary textures and mineral associations in the ultramafic zone of the stillwater complex, Montana. U.S. Geological Survey Professional Paper358: 1–103.
     [Google Scholar]
  34. Jackson, E.D.1968. The chromite deposits of the Stillwater Complex, Montana. In Ore deposits of the United States, 1933-1967 (Graton-sales volume), ed. J.D.Ridge, 1495–1510. New York: American Institute of Mining, Metallurgical and Petroleum Engineers.
     [Google Scholar]
  35. Jenkins, M.C., and J.E.Mungall. 2018. Genesis of the peridotite zone, Stillwater Complex, Montana, USA. Journal of Petrology59 no. 11: 2157–2189.
     [Google Scholar]
  36. Jenkins, M.C., J.E.Mungall, M.L.Zientek, K.Butak, S.Corson, P.Holick, R.McKinley, and H.Lowers. 2022. The geochemical and textural transition between the reef package and its hanging wall, Stillwater Complex, Montana, USA. Journal of Petrology63 no. 7: egac053.
     [Google Scholar]
  37. Jenkins, M.C., J.E.Mungall, M.L.Zientek, G.Costin, and Z.sen Yao. 2021. Origin of the J-M reef and lower banded series, stillwater complex, Montana, USA. Precambrian Research367: 106457.
     [Google Scholar]
  38. Jenkins, M.C., J.E.Mungall, M.L.Zientek, P.Holick, and K.Butak. 2020. The nature and composition of the J-M reef, Stillwater Complex, Montana, USA. Economic Geology115 no. 8: 1799–1826.
     [Google Scholar]
  39. Jones, W.R., J.W.Peoples, and A.L.Howland. 1960. Igneous and tectonic structures of the Stillwater Complex, Montana. US Geological Survey Bulletin 1071-H, 340 pp.
  40. Keller, G.V.1966. Electrical properties of rocks and minerals. In Handbook of physical constants, ed. Sydney P.Clark, Jr. Revised ed., 97. Boulder: Geological Society of America Memoir.
     [Google Scholar]
  41. Kilgore, B., and R.D.Elmore. 1989. A study of the relationship between hydrocarbon migration and the precipitation of authigenic magnetic minerals in the triassic chugwater formation, southern Montana. Geological Society of America Bulletin101 no. 10: 1280–1288.
     [Google Scholar]
  42. Kwan, K., and R.Mirza. 2022. Geophysical signatures of the Ni-Cu-PGE mineralization in the Stillwater West property, Stillwater Complex, southern Montana, USA.
  43. Ley-Cooper, A.Y., R.C.Brodie, and M.Richardson. 2020. AusAEM: Australia’s airborne electromagnetic continental-scale acquisition program. Exploration Geophysics51 no. 1: 193–202.
     [Google Scholar]
  44. Ley-Cooper, A.Y., A.Viezzoli, J.Guillemoteau, G.Vignoli, J.Macnae, L.Cox, and T.Munday. 2015. Airborne electromagnetic modelling options and their consequences in target definition. Exploration Geophysics46 no. 1: 74–84.
     [Google Scholar]
  45. McCallum, I.1996. The stillwater complex. Developments in Petrology15: 441–483.
     [Google Scholar]
  46. McCallum, I., L.Raedeke, and E.Mathez. 1980. Investigations of the Stillwater Complex: part I. stratigraphy and structure of the banded zone. American Journal of Science280 no. 1: 59–87.
     [Google Scholar]
  47. Meyer, R., and J.De Beer. 1987. Structure of the Bushveld Complex from resistivity measurements. Nature325 no. 12: 610–612.
     [Google Scholar]
  48. Miller, H.G., and V.Singh. 1994. Potential field tilt - a new concept for location of potential field sources. Journal of Applied Geophysics32: 213–217.
     [Google Scholar]
  49. Mogk, D.W., P.A.Mueller, and D.J.Henry. 2020. The Archean geology of Montana, Geology of Montana, Vol. I, Geologic history. Montana Bureau of Mines and Geology Special Publication, 45 p.
  50. Oldenburg, D.W., and F.H.M.Jones. 2011. “A Program Library for Forward Modelling and Inversion of Frequency Domain Electromagnetic Data over 1D Structures, version 1.0, Developed by the UBC-Geophysical Inversion Facility.” Department of Earth and Ocean Sciences, University of British Columbia, Vancouver.
  51. Page, N.J.1977. Stillwater Complex, Montana; rock succession, metamorphism and structure of the complex and adjacent rocks. U.S. Geological Survey Bulletin Professional Paper 999: 1–79.
  52. Page, N.J.1979. Stillwater Complex, Montana: Structure, mineralogy, and petrology of the Basal Zone with emphasis on the occurrence of sulfides. U. S. Geological Survey Professional Paper 1038: 1–69.
  53. Page, N.J., and W.J.Nokleberg. 1974. Geologic map of the Stillwater Complex, Montana. U.S.G.S.M.I.S.M. I–797.
  54. Parks, H.L., B.R.Bloss, M.R.Johnson, and C.A.Finn. 2019. “Airborne electromagnetic and magnetic survey data, Stillwater Complex, Montana, May 2000 (ver. 2.0, June 2020).” U.S. Geological Survey data release. https://doi.org/10.5066/P92R4OL2.
     https://doi.org/https://doi.org/10.5066/P92R4OL2
  55. Parks, H.L., and M.L.Zientek. 2019. Stillwater Complex, Montana - Logs of core drilled by AMAX, 1969 to 1977. U.S. Geological Survey data release.
  56. Peterson, D.E., C.Finn, and P.Bedrosian. 2019. Airborne electromagnetic and magnetic imaging of weak zones on Iliamna Volcano, Alaska. American Geophysical Union Fall Meeting, San Francisco, CA.
  57. Pilkington, M., and V.Tschirhart. 2017. Practical considerations in the use of edge detectors for geologic mapping using magnetic data. Geophysics82 no. 3: J1–J8.
     [Google Scholar]
  58. Price, P.L.1963. Mining methods and costs, Mouat Mine, American Chrome Co., Stillwater County. Montana US Bureau of Mines Information Circular8204: 1–58.
     [Google Scholar]
  59. Prichard, H.M., S.Barnes, P.C.Fisher, P.Pagé, and M.L.Zientek. 2017. Laurite and associated PGM in the stillwater chromitites: implications for processes of formation, and comparisons with laurite in the Bushveld and ophiolitic chromitites. Canadian Mineralogist55 no. 1: 121–144.
     [Google Scholar]
  60. Radbruch-Hall, D.H., D.J.Varnes, and W.Z.Savage. 1976. Gravitational spreading of steep-sided ridges (“sackung”) in western United States. Bulletin of the International Association of Engineering Geology14: 23–25.
     [Google Scholar]
  61. Raedeke, L., and I.McCallum. 1984. Investigations in the stillwater complex: part II. Petrology and petrogenesis of the ultramafic series. Journal of Petrology25 no. 2: 395–420.
     [Google Scholar]
  62. Rea, B.R.2006. Plateau icefield system. In Glacier science and environmental change, ed. P.G.Knight, 91–94. Malden, MA: Blackwell Science, Ltd.
     [Google Scholar]
  63. Rea, B.R., W.B.Whalley, D.Evens, J.E.Gordon, and D.A.McDougall. 1998. Plateau icefields: geomorphology and dynamics. Journal of Quaternary Science13 no. 6: 35–54.
     [Google Scholar]
  64. Segerstrom, K., and R.R.Carlson. 1982. “Geologic map of the banded upper zone of the Stillwater Complex and adjacent rocks, Stillwater, Sweet Grass, and Park Counties, Montana.” U.S. Geological Survey Miscellaneous Investigations Series Map I-1383: 2 sheets, scale 1:24,000.
  65. Simons, F.S., and T.J.Armbrustmacher. 1976. High-level plateaus of the southeastern Beartooth mountains, Montana and Wyoming—remnants of an exhumed sub- Cambrian marine plain. Journal of Research of the U.S. Geology Survey4: 387–396.
     [Google Scholar]
  66. Stewart, I.C., and D.T.Miller. 2018. Directional tilt derivatives to enhance structural trends in aeromagnetic grids. Journal of Applied Geophysics159: 553–563.
     [Google Scholar]
  67. Supper, R., I.Baroň, D.Ottowitz, K.Motschka, S.Gruber, E.Winkler, B.Jochum, and A.Römer. 2013. Airborne geophysical mapping as an innovative methodology for landslide investigation: evaluation of results from the Gschliefgraben landslide, Austria. Natural Hazards and Earth System Sciences13 no. 12: 3313–3328.
     [Google Scholar]
  68. Ten Brink, N.W.1968. “Pleistocene geology of the Stillwater drainage and Beartooth Mountains near Nye, Montana.” M.S. thesis, Franklin and Marshall College, Lancaster, Pa., 172 pp.
  69. Ten Brink, N.W.1972. Glacial geology of the stillwater drainage and Beartooth mountains near Nye, Montana. Geological Society of America Abstracts with Programs4: 415.
     [Google Scholar]
  70. Thacker, J.O., D.R.Lageson, and D.W.Mogk. 2017. Subsurface structural and mineralogical characterization of the laramide south prairie fault in the Stillwater Complex, Beartooth mountains, Montana. Lithosphere9 no. 1: 100–116.
     [Google Scholar]
  71. Todd, S., D.Keith, L.Le Roy, D.Schissel, E.Mann, and T.Irvine. 1982. The JM platinum-palladium reef of the Stillwater Complex, Montana; I, stratigraphy and petrology. Economic Geology77 no. 6: 1454–1480.
     [Google Scholar]
  72. Turner, A.R., D.Wolfgram, and S.J.Barnes. 1985. Geology of the stillwater county sector of the J-M reef, including the Minneapolis adit. Stillwater Complex. Montana Bureau of Mines and Geology Special Publication92: 210–230.
     [Google Scholar]
  73. U.S. Bureau of Mines. 1945. Taylor-Fry area, Stillwater Complex, Sweetgrass County, Mont., Supplement to W.M.R.390. United States Department of the Interior - Bureau of Mines War Minerals Report, 397 - Chromite: 8.
  74. U.S. Geological Survey. 2017. USGS Lidar Point Cloud MT Stillwater 2016 12TWR715250 LAS 2017. https://www.sciencebase.gov/catalog/item/5ace19fbe4b0e2c2dd178a03, ScienceBase.
  75. Varnes, D.J., D.H.Radbruch-Hall, and W.Z.Savage. 1989. Topographic and structural conditions in areas of gravitational spreading of ridges in the western United States. U.S. Geological Survey Professional Paper1496: 1–28.
     [Google Scholar]
  76. Volborth, A., and R.M.Housley. 1984. A preliminary description of complex graphite, sulphide, arsenide, and platinum group element mineralization in a pegmatoid pyroxenite of the Stillwater Complex, Montana, U.S.A. Tschermaks Mineralogische und Petrographische Mitteilungen33: 213–230.
     [Google Scholar]
  77. Wall, C.J., J.S.Scoates, D.Weis, R.M.Friedman, M.Amini, and W.P.Meurer. 2018. The Stillwater Complex: integrating zircon geochronological and geochemical constraints on the age, emplacement history and crystallization of a large, open-system layered intrusion. Journal of Petrology59 no. 1: 153–190.
     [Google Scholar]
  78. Wimmler, N.L.1948. Investigation of chromite deposits of the Stillwater Complex, stillwater and sweetgrass counties, Montana. US Bureau of Mines Report of Investigations4368: 1–40.
     [Google Scholar]
  79. Xu, W., J.W.Geissman, R.Van der Voo, and D.R.Peacor. 1997. Electron microscopy of iron oxides and implications for the origin of magnetizations and rock magnetic properties of banded series rocks of the Stillwater Complex, Montana. Journal of Geophysical Research: Solid Earth102 no. B6: 12139–12157.
     [Google Scholar]
  80. Zablocki, C.J.1966. “Electrical Properties of Some Iron Formations and Adjacent Rocks in the Lake Superior Region†, Mining Geophysics Volume 1, Case Histories.” Society of Exploration Geophysicists, 0.
  81. Zientek, M.1983. “Petrogenesis of the Basal zone of the Stillwater Complex, Montana,” Unpub, Ph. D. thesis, Stanford Univ.
  82. Zientek, M., R.Cooper, S.Corson, and E.Geraghty. 2002. Platinum-group element mineralization in the Stillwater Complex, Montana. In The geology, geochemistry, mineralogy and mineral beneficiation of platinum-group elements special issue, ed. L.Cabri., 459–481. Montreal: Canadian Institute of Mining, Metallurgy amd Petroleum.
     [Google Scholar]
  83. Zientek, M., G.Czamanske, and T.Irvine. 1985. Stratigraphy and nomenclature for the Stillwater Complex. The Stillwater Complex, Montana: geology and guide, butte, Montana. Montana Bureau of Mines and Geology, Spec. Publ92: 21–32.
     [Google Scholar]
  84. Zientek, M.L., P.J.Loferski, H.L.Parks, R.F.Schulte, and RRSealII. 2017. Platinum-group elements. U.S. Geological Survey Professional Paper, 1802N: N1–N91.
  85. Zientek, M.L., and H.L.Parks. 2014. A geologic and mineral exploration spatial database for the Stillwater Complex, Montana. U.S. Geological Survey Scientific Investigations Report, 2014–5183: 1–40.
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Electromagnetic and magnetic imaging of the Stillwater Complex, Montana, USA
Exploration Geophysics 54, 553 (2023); https://doi.org/10.1080/08123985.2023.2214166
/content/journals/10.1080/08123985.2023.2214166
/content/journals/10.1080/08123985.2023.2214166
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  • Article Type: Research Article
Keyword(s): economic geology; electromagnetic; Geophysics; resistivity; Stillwater Complex; susceptibility

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