Geoscience Canada

Vol. 50 No. 2 (2023)
Series

Igneous Rock Associations 29. The Nenana Magnetitite Lava Flow, Alaska Range, Alaska

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  • S.P. Reidel,
  • M.E. Ross,
  • J. Kasbohm
S.P. Reidel
Pacific Northwest National Laboratory, Retired, Present address: 7207 West Old Inland Empire Highway Benton City, Washington 99320, USA
Bio
M.E. Ross
Professor Emeritus, Department of Marine and Environmental Sciences, Northeastern University, Boston, Massachusetts 02115, USA
J. Kasbohm
Department of Earth and Planetary Sciences, Yale University New Haven, Connecticut 06511, USA
DOI: https://doi.org/10.12789/geocanj.2023.50.197

Published 2023-07-17

Keywords

  • Alaska Range,
  • Late Miocene,
  • Magnetitite Lava,
  • Nenana Basin,
  • Rhyolite

How to Cite

Reidel, S. P., Ross, M. E., & Kasbohm, J. (2023). Igneous Rock Associations 29. The Nenana Magnetitite Lava Flow, Alaska Range, Alaska. Geoscience Canada, 50(2), 53–71. https://doi.org/10.12789/geocanj.2023.50.197
Copyright Notice

Abstract

Magnetitite deposits like El Laco (Chile) are rare and have controversial origins. An unusual magnetitite lava flow overlying a rhyolite unit occurs in the north-central Alaska Range and originally covered ~ 750 km2 of the Miocene Nenana basin. Dating of the rhyolite and relationships between the magnetitite and sedimentary rocks indicate that both are of Late Miocene age. The magnetitite flow is mainly magnetite with some post-eruptive alteration to hematite. Both the rhyolite flow and the magnetitite flow are vesicular, but the magnetitite flow also has small, millimetre-scale columnar jointing. The vesicular zones in the magnetitite flow grade into massive rock on the scale of a thin section, suggesting a degassing lava origin. Samples of the magnetitite flow contain between 12 and 26 wt.% SiO2 and between 45 and 75 wt.% FeO. Rare earth elements (REE) and trace elements from the magnetitite and rhyolite have similar patterns but with lesser abundance in the magnetitite. Both the rhyolite and the magnetitite have light-REE-enriched REE profiles with negative Eu anomalies. Electron microscopic analysis shows that most of the silica and trace element content of the magnetitite flow comes from very finely disseminated silicate minerals and glass in the magnetite. This suggests that the magnetitite was derived from a magma that had undergone unmixing into a silica-rich phase and an iron-rich phase prior to its eruption. Fractures and vesicles within the magnetitite flow contain minor rhyolitic glass and minerals suggesting that the rhyolite magma invaded columnar joints in the solidified magnetitite flow, and is a subvolcanic sill-like body at the studied locality. The magnetitite flow erupted prior to the emplacement of the rhyolite, which may be extrusive on a regional scale. The features of the Nenana magnetitite, and its geological relationships, are consistent with genetic models that invoke unmixing of magma into immiscible Fe-rich and Si-rich liquids during ascent.

 

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References

  1. Alaska Division of Geological and Geophysical Surveys, 1973a, Aeromagnetic survey, east Alaska Range, Fairbanks Quadrangle, Alaska, scale 1:250,000,1 sheet.
  2. Alaska Division of Geological and Geophysical Surveys, 1973b, Aeromagnetic survey, east Alaska Range, Healy Quadrangle, Alaska, scale 1:250,000, 1 sheet.
  3. Albanese, M.D., 1980, The geology of three extrusive bodies in the central Alaska Range: Unpublished MSc thesis, University of Alaska Fairbanks, 104 p., http://hdl.handle.net/11122/5943.
  4. Athey, J.E., Newberry, R.J., Werdon, M.B., Freeman, L.K., Smith, R.L., and Szimugala, D.J., 2006, Bedrock geological map of the Liberty Bell area, Fairbanks A-4 Quadrangle, Bonnifield Mining District, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigation 2006-2, scale 1:50,000, 98 p.
  5. Bain, W.M., Steele-MacInnis, M., Tornos, F., Hanchar, J.M., Creaser, E.C., and Pietruszka, D.K., 2021, Evidence for iron-rich sulfate melt during magnetite (-apatite) mineralization at El Laco, Chile: Geology, v. 49, p. 1044–1048, https://doi.org/10.1130/G48861.1.
  6. Beikman, H.M., compiler, 1974, Preliminary geologic map of the southeast quadrant of Alaska: U.S. Geological Survey Miscellaneous Field Studies Map 612, 2 sheets, scale 1:1,000,000.
  7. Bowring, J.F., McLean, N.M., and Bowring, S.A., 2011, Engineering cyber infrastructure for U–Pb geochronology: Tripoli and U–Pb_Redux: Geochemistry, Geophysics, Geosystems, v. 12, Q0AA19, https://doi.org/10.1029/2010GC003479.
  8. Condon, D.J., Schoene, B., McLean, N.M., Bowring, S.A., and Parrish, R.R., 2015, Metrology and traceability of U–Pb isotope dilution geochronology (EARTHTIME Tracer Calibration Part I): Geochimica et Cosmochimica Acta, v. 164, p. 464–480, https://doi.org/10.1016/j.gca.2015.05.026.
  9. Dare, S.A.S., Barnes, S.-J., and Beaudoin, G., 2015, Did the massive magnetite "lava flows" of El Laco (Chile) form by magmatic or hydrothermal processes? New constraints from magnetite composition by LA-ICP-MS: Mineralium Deposita, v. 50, p. 607–617, https://doi.org/10.1007/s00126-014-0560-1.
  10. Dusel-Bacon, C., Aleinikoff, J.N., Premo, W.R., Paradis, S., and Lohr-Schmidt, I., 2007, Tectonic setting and metallogenesis of volcanogenic massive sulfide deposits in the Bonnifield Mining District, Northern Alaska Range, in Gough, L.P., and Day, W.C., eds., Recent U.S. Geological Survey Studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada—Results of a 5-Year Project: U.S. Geological Survey Scientific Investigations Report 2007–5289-B, p. B1–B7, https://doi.org/10.3133/sir20075289B.
  11. Freeman, L.K., Newberry, R.J., Werdon, M.B., Szumigala, D.J., Andrew, J.E., and Athey, J.E., 2016, Preliminary bedrock geologic map data for the eastern Bonnifield mining district, Fairbanks and Healy quadrangles, Alaska: Alaska Division of Geological and Geophysical Surveys Preliminary Interpretive Report 2016-3, 6 p., https://doi.org/10.14509/29661.
  12. Frietsch, R., 1978, On the magmatic origin of iron ores of the Kiruna type: Economic Geology, v. 73, p. 478–485, https://doi.org/10.2113/gsecongeo.73.4.478.
  13. Gerstenberger, H., and Haase, G., 1997, A highly effective emitter substance for mass spectrometric Pb isotope ratio determinations: Chemical Geology, v. 136, p. 309–312, https://doi.org/10.1016/S0009-2541(96)00033-2.
  14. Gholipoor, M., Barati, M., Tale Fazel, E., and Hurai, V., 2023, Textural and compositional constraints on the origin, thermal history, and REE mobility in the Lakeh Siah iron oxide-apatite deposit—NE Bafq, Iran: Mineralium Deposita, v. 58, p. 963–986, https://doi.org/10.1007/s00126-023-01163-1.
  15. Henriquez, F., Naslund, H.R., Nyström, J.O., Vivallo, W., Aguirre, R., Dobbs, F.M., and Lledó, H., 2003, New field evidence bearing on the origin of the El Laco magnetite deposit, northern Chile - A Discussion: Economic Geology, v. 98, p. 1497–1500, https://doi.org/10.2113/gsecongeo.98.7.1497.
  16. Hickey, R.L., Frey, F.A., Gerlach, D.C., and Lopez-Escobar, L., 1986, Multiple sources for basaltic arc rocks from the southern volcanic zone of the Andes (34°–41°S): Trace element and isotopic evidence for contributions from subducted oceanic crust, mantle, and continental crust: Journal of Geophysical Research, v. 91, p. 5963–5983, https://doi.org/10.1029/JB091iB06p05963.
  17. Holmes, A., 1928, The Nomenclature of Petrology, second edition: Thomas Murby and Co., London, 248 p.
  18. Jaffey, A.H., Flynn, K.F., Glendenin, L.E., Bentley, W.C., and Essling, A.M., 1971, Precision measurement of half-lives and specific activities of 235U and 238U: Physical Review C, v. 4, p. 1889–1906, https://doi.org/10.1103/PhysRevC.4.1889.
  19. Johannsen, A., 1931–1938, A Descriptive Petrology of Igneous Rocks, Volumes 1–4: University of Chicago Press.
  20. Johnson, D.M., Hooper, P.R., and Conrey, R.M., 1999, XRF Analysis of rocks and minerals for major and trace elements on a single low dilution Li-tetraborate fused bead: Advances in X-Ray Analysis, v. 41, p. 843–867.
  21. Kasbohm, J., and Schoene, K., 2018, Rapid eruption of the Columbia River flood basalt and correlation with the mid-Miocene climate optimum: Science Advances, v. 4, eaat8223, https://doi.org/10.1126/sciadv.aat8223.
  22. Keller, T., Tornos, F., Hanchar, J.M., Pietruszka, D.K., Soldati, A., Dingwell, D.B., and Suckale, J., 2022, Genetic model of the El Laco magnetite-apatite deposits by extrusion of iron-rich melt: Nature Communications, v. 13, 6114, https://doi.org/10.1038/s41467-022-33302-z.
  23. Kirschner, C.E., 1994, Interior basins of Alaska, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska, The Geology of North America, Decade of North American Geology: Geological Society of America, v. G-1, p. 469–493, https://doi.org/10.1130/DNAG-GNA-G1.469.
  24. Krogh, T.E., 1973, A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations: Geochimica et Cosmochimica Acta, v. 37, p. 485–494, https://doi.org/10.1016/0016-7037(73)90213-5.
  25. Leopold, E.B., and Liu, G., 1994, A long pollen sequence of Neogene age, Alaska Range: Quaternary International, v. 22–23, p. 103–140, https://doi.org/10.1016/1040-6182(94)90009-4.
  26. Lyons, J.I.,1988, Volcanogenic iron oxide deposits, Cerro de Mercado and vicinity, Durango: Economic Geology, v. 83, p. 1886–1906, https://doi.org/10.2113/gsecongeo.83.8.1886.
  27. Mattinson, J.M., 2005, Zircon U–Pb chemical abrasion (“CA-TIMS”) method: Combined annealing and multi-step partial dissolution analysis for improved precision and accuracy of zircon ages: Chemical Geology, v. 220, p. 47–66, https://doi.org/10.1016/j.chemgeo.2005.03.011.
  28. McLean, N.M., Bowring, J.F., and Bowring, S.A., 2011, An algorithm for U–Pb isotope dilution data reduction and uncertainty propagation: Geochemistry, Geophysics, Geosystems, v. 12, Q0AA18, https://doi.org/10.1029/2010GC003478.
  29. McLean, N.M., Condon, D.J., Schoene, B., and Bowring, S.A., 2015, Evaluating uncertainties in the calibration of isotopic reference materials and multi-element isotopic tracers (EARTHTIME Tracer Calibration Part II): Geochimica et Cosmochimica Acta, v. 164, p. 481–501, https://doi.org/10.1016/j.gca.2015.02.040.
  30. Miller, J.S., Matzel, J.E.P., Miller, C.F., Burgess, S.D., and Miller, R.B., 2007, Zircon growth and recycling during the assembly of large, composite arc plutons: Journal of Volcanology and Geothermal Research, v. 167, p. 282–299, https://doi.org/10.1016/j.jvolgeores.2007.04.019.
  31. Naslund, H.R., Henriquez, F., Nyström, J.O., Vivallo, W., and Dobbs, F.M., 2002, Magmatic iron ores and associated mineralisation: Examples from the Chilean High Andes and Coastal Cordillera, in Porter, T.M., ed., Hydrothermal iron oxide copper-gold and related deposits: A global perspective: Porter Geoscience Consultancy Publishing, Adelaide, v. 2, p. 207–226.
  32. Nier, A.O., 1950, A redetermination of the relative abundances of the isotopes of carbon, nitrogen, oxygen, argon, and potassium: Physical Review, v. 77, p. 789–793, https://doi.org/10.1103/PhysRev.77.789.
  33. Parak, T., 1985, Phosphorus in different types of ore sulfides in the iron deposits, and the type and origin of ores at Kiruna: Economic Geology, v. 80, p. 646–665, https://doi.org/10.2113/gsecongeo.80.3.646.
  34. Park, C.F., 1961, A magnetite "flow" in northern Chile: Economic Geology, v. 56, p. 431–441, https://doi.org/10.2113/gsecongeo.56.2.431.
  35. Péwé, T.L., Wahrhaftig, C., and Webber, F., 1966, Geologic map of the Fairbanks quadrangle, Alaska: U.S. Geological Survey Miscellaneous Geologic Investigations Map 455, scale 1:250,000.
  36. Pietruszka, D.K., Hanchar, J.M., Tornos, F., Whitehouse, M.J., and Velasco, F., 2023, Tracking isotopic sources of immiscible melts at the enigmatic magnetite-(apatite) deposit at El Laco, Chile, using Pb isotopes: Geological Society of America Bulletin, https://doi.org/10.1130/B36506.1.
  37. Reidel, S.P., 1984, An iron-rich lava flow from the Nenana coal field, central Alaska: in Short Notes on Alaskan Geology 1982–1983: Alaska Division of Geology and Geophysical Surveys, Professional Report 86B, p. 5–8, https://doi.org/10.14509/2261.
  38. Reidel, S.P., and Ross, M.E., in press, A rare sekaninaite occurrence in the Nenana Coal Basin, Alaska Range, Alaska: American Mineralogist, https://doi.org/10.2138/am-2022-8698.
  39. Reidel, S.P., Camp, V.E., Tolan, T.L., and Martin, B.S., 2013, The Columbia River flood basalt province, Stratigraphy, areal extent, volume, and physical volcanology, in Reidel, S.P., Camp, V.E., Ross, M.E., Wolff, J.A., Martin, B.S., Tolan, T.L, and Wells, R.E., eds., The Columbia River Flood Basalt Province: Geological Society of America Special Papers, v. 497, p. 1–43, https://doi.org/10.1130/2013.2497(01).
  40. Ross, M.E., 1989, Stratigraphic relationships of subaerial, invasive, and intracanyon flows of Saddle Mountains Basalt in the Troy basin, Oregon and Washington, in Reidel, S.P., and Hooper, P.R., eds., Volcanism and Tectonism in the Columbia River Flood-Basalt Province: Geological Society of America Special Papers, v. 237, p. 131–142, https://doi.org/10.1130/SPE239-p131.
  41. Sillitoe, R.H., and Burrows, D.B., 2002, New field evidence bearing on the origin of the El Laco magnetite deposit, northern Chile: Economic Geology, v. 97, p. 1101–1109, https://doi.org/10.2113/gsecongeo.97.5.1101.
  42. Sillitoe, R.H., and Burrows, D.B., 2003, New field evidence bearing on the origin of the El Laco magnetite deposit, northern Chile - A Reply: Economic Geology, v. 98, p. 1501–1502, https://doi.org/10.2113/gsecongeo.98.7.1501.
  43. Simon, J.I., Renne, P.R., and Mundil, R., 2008, Implications of pre-eruptive magmatic histories of zircons for U–Pb geochronology of silicic extrusions: Earth and Planetary Science Letters, v. 266, p. 182–194, https://doi.org/10.1016/j.epsl.2007.11.014.
  44. Sortor, R.N., Goehring, B.M., Bemis, S.P., Ruleman, C.A., Caffee, M.W., and Ward, D.J., 2021, Early Pleistocene climate-induced erosion of the Alaska Range formed the Nenana Gravel: Geology, v. 49, p. 1473–1477, https://doi.org/10.1130/G49094.1.
  45. Sun, S.-s., and McDonough, W.F., 1989, Chemical and isotopic systematics of oceanic basalts: Implications for mantle composition and processes, in Saunders, A.D., and Norry, M.J., eds., Magmatism in the Ocean Basins: Geological Society Special Publications, v. 42, p. 313–345, https://doi.org/10.1144/GSL.SP.1989.042.01.19.
  46. Triplehorn, D.M., Drake, J., and Layer, P.W., 2000, Preliminary 40Ar/39Ar ages from two units in the Usibelli Group, Healy, Alaska: New light on some old problems, in Pinney, D.S., and Davis, P.K., eds., Short Notes on Alaska Geology 1999: Alaska Division of Geological and Geophysical Surveys Professional Report 119I, p. 117–127, https://doi.org/10.14509/2691.
  47. Wahrhaftig, C., 1951, Geology and coal deposits of the western part of the Nenana coal field, Alaska, in Barnes, F.F., ed., Coal investigations in south-central Alaska, 1944–46: U.S. Geological Survey Bulletin 963-E, p. 169–186.
  48. Wahrhaftig, C., 1970a, Geologic map of the Healy D-2 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-804, scale 1:63,360, 1 sheet.
  49. Wahrhaftig, C.,1970b, Geologic map of the Healy D-3 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-805, scale 1:63,360, 1 sheet.
  50. Wahrhaftig, C., 1970c, Geologic map of the Healy D-4 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-806, scale 1:63,360, 1 sheet.
  51. Wahrhaftig, C., 1970d, Geologic map of the Healy D-5quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-807, scale 1:63,360, 1 sheet.
  52. Wahrhaftig, C., 1970e, Geologic map of the Fairbanks A-2 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-808, scale 1:63,360, 1 sheet.
  53. Wahrhaftig, C., 1970f, Geologic map of the Fairbanks A-3 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-809, scale 1:63,360, 1 sheet.
  54. Wahrhaftig, C., 1970g, Geologic Map of the Fairbanks A-4 Quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map 810, scale 1:63,360, 1 sheet, https://dggs.alaska.gov/webpubs/usgs/gq/oversized/gq-0810sht01.pdf.
  55. Wahrhaftig, C., 1970h, Geologic map of the Fairbanks A-5 quadrangle, Alaska: U.S. Geological Survey Geologic Quadrangle Map GQ-811, scale 1:63,360, 1 sheet.
  56. Wahrhaftig, C., 1987, The Cenozoic section at Suntrana, Alaska, in Hill, M.L., ed., Cordilleran Section of the Geological Society of America: Geological Society of America, The Decade of North American Geology (DNAG), Centennial Field Guide 1, p. 445–450, https://doi.org/10.1130/0-8137-5401-1.445.
  57. Wahrhaftig, C., Wolfe, J.A., Leopold, E.B., and Lanphere, M.A., 1969, The coal-bearing group in the Nenana coal field, Alaska: Contributions to Stratigraphy: U.S. Geological Survey Bulletin 1274-D, p. D1–D30, https://doi.org/10.3133/b1274D.
  58. Wartes, M.A, Gillis, R.J., Herriott, T.M., Stanley, R.G., Helmold, K.P., Peterson, C.S., and Benowitz, J.A., 2013, Summary of the 2012 reconnaissance field studies related to petroleum geology of the Nenana basin, interior Alaska: Division of Geological and Geophysical Surveys, Alaska Geological Survey, Preliminary Interpretive Report 2013-2, 13 p., https://doi.org/10.14509/24880.
  59. Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report OF 98-133-A, version 1.2, https://pubs.usgs.gov/of/1998/of98-133-a/.
  60. Wolfe, J.A., and Tanai, T., 1987, Systematics, phylogeny, and distribution of Acer (Maples) in the Cenozoic of western North America: Journal of the Faculty of Science, Hokkaido University, v. 22, p. 1–246, http://hdl.handle.net/2115/36747.