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Overview

location map
Simplified geology map of the study area in the Alaska Range, Alaska, with sample locations. From USGS Open-File Report 2014-1115.

Scientific Issue and Relevance

There are many different types of mineral deposits present in the Western Alaska Range: plutonic gold, porphyry copper-gold (Pebble prospect), epithermal gold, tin-silver skarns, sedimentary barite, mafic hosted nickle-platinum-group elements, uranium-thorium rare earth elements, and even a diamond prospect. All of these have been the targets of recent exploration efforts, but their relationships to the regional magmatic belts and stratigraphy is not known. Improved understanding of Alaska's geologic framework will help to put these mineral deposits into a regional magmatic and tectonic framework, which is the best predictor of mineral occurrence and contribute to improved assessments of undiscovered resources. The Nation will have more accurate estimates of the national mineral endowment as improvements are made concerning the distribution of these deposits, their age, and genetic processes that define the localization of the mineralizing events.

Research Activities

The project objectives were to produce an improved model of the geologic framework underpinning the Western Alaska Range in south-central Alaska. Numerous ore deposits are present in this region, and most appear to be associated with magmatic events, but the ages and types of mineral deposits in relation to their host rocks needed to be identified. We conducted detailed geologic studies to delineate the magmatic, stratigraphic, and tectonic differences that distinguish this area from adjacent geologic terranes. Field mapping, geochronology, thermochronology, geochemical analyses, and geophysical data contributed to an improved understanding of the relationship between ore deposits and tectonic architecture that is critical to an assessment of the overall mineral potential of the area. Our main tasks are below.

  • Produce a new geologic map of the western Alaska Range.
  • Metallogeny of the western Alaska Range.
  • Petrogenesis of western Alaska Range igneous rocks.
  • Geophysical framework of the western Alaska Range.
  • Exhumation, erosion, and tectonics of the western Alaska Range.
  • Framework geology for mineral assessment.

Products

Publications

Bradley, D., Haeussler, P., O'Sullivan, P., Friedman, R., Till, A., Bradley, D., and Trop, J., 2009, Detrital zircon geochronology of Cretaceous and Paleogene strata across the south-central Alaskan convergent margin, in Haeussler, P.J., and Galloway, J.P., Studies by the U.S. Geological Survey in Alaska, 2007: U.S. Geological Survey Professional Paper 1760-F, 36 p., https://pubs.usgs.gov/pp/1760/f/.

Bradley, D.C., McClelland, W.C., Friedman, R.M., O'Sullivan, P., Layer, P.W., Miller, M.L., Dumoulin, J.A., Till, A.B., Abbott, J.G., Bradley, D.B., and Wooden, J.L., 2014, Proterozoic Geochronological Links between the Farewell, Kilbuck, and Arctic Alaska Terranes: The Journal of Geology 122(3), p. 237-258, doi:10.1086/675663.

Garth, G.E., Taylor, R.D., Lee, G.K., and Tripp, R.B., 2015, Targeting Cu–Au and Mo resources using multi-media exploration geochemistry: An example from Tyonek Quadrangle, Alaska Range, Alaska: Journal of Geochemical Exploration, 157, p. 52-65, doi:10.1016/j.gexplo.2015.05.014.

Lease, R.O., Haeussler, P.J., and O'Sullivan, P., 2016, Changing exhumation patterns during Cenozoic growth and glaciation of the Alaska Range: Insights from detrital thermochronology and geochronology: Tectonics, 35(4), p. 934-955, doi:10.1002/2015TC004067.

Saltus, R.W., Stanley, R.G., Haeussler, P.J., Jones, J.V., Potter, C.J., and Lewis, K.A., 2016, Late Oligocene to present contractional structure in and around the Susitna basin, Alaska—Geophysical evidence and geological implications: Geosphere, 12(5), p. 1378-1390, doi:10.1130/GES01279.1.

Taylor, R.D., Graham, G.E., Anderson, E.D., and Selby, David, 2014, Timing of ore-related magmatism in the western Alaska Range, southwestern Alaska: U.S. Geological Survey Open-File Report 2014–1115, 25 p., https://doi.org/10.3133/ofr20141115.

Abstracts

Ayuso, R., Haeussler, P., Todd, E., Box, S., Jones, J., Bradley, D., Vazuez, J., Karl, S., and Jackson, J., 2014, Geochronological and geochemical transects of the western Alaska Range batholith: Goldschmidt Abstracts, p. 89. View Ayuso Goldschmidt abstract.

Box, S.E., Ayuso, R.A., Bradley, D.C., Haeussler, P.J., Saltus, R.W., Karl, S.M., Jones, J.V., Dumoulin, J.A., Graham, G.E., Todd, E., and Lease, R.O., 2012, A geologic transect across the western Alaska Range: 2012 Alaska Miners Association Annual Convention, 5-11 November, 2012, Anchorage, AK.

Box, S.E., Jones, J.V. III, Todd, E., Karl, S.M., Dumoulin, J.A., Ayuso, R.A., Haeussler, P.J., Bradley, D.W., Graham, G., and Lease, R.O., 2015, New 1:250,000 geologic map of the western Alaska Range: Portions of the Lime Hills, McGrath, Talkeetna, and Tyonek quadrangles: Geological Society of America Abstracts with Programs, Vol. 47, No. 4, p. 53. View Box 2015 GSA abstract.

Box, S.E., Karl, S.M., Jones, J.V. III, Lease, R.O., Bradley, D.C., Haeussler, P.J., Graham, G., Saltus, R.W., and Hults, C.P., 2013, Detrial zircon constraints on sources, age of deformation and localization of mineral deposits of Kahiltna basin, south-central Alaska: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 77. View Box 2013 GSA abstract.

Dumoulin, J.A., Bradley, D.C., Till, A.B., Box, S.E., and Jones, J.V. III, 2013, Strikingly familiar early Paleozoic provenance evolution of sedimentary rocks in the Farewell terrane (interior Alaska) and Arctic Alaska-Chukotka terrane: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 78. View Dumoulin 2013 GSA abstract.

Dumoulin, J.A., Jones, J.V. III, Box, S.E., and Bradley, D.C., 2015, The Mystic subterrane (partly) demystified: New data from the Farewell terrane, interior Alaska: Geological Society of America Abstracts with Programs, Vol. 47, No. 4, p. 53. View Dumoulin 2015 GSA abstract.

Graham, G.E., Goldfarb, R.J., Miller, M.L., Gibler, K., and Roberts, M., 2013, Tectonic Evolution and Cretaceous Gold Metallogenesis in Southwestern Alaska - A Review: Society of Economic Geologists 2013 Conference, 24-27 September, 2013, Whistler, BC.

Graham, G., Taylor, R.D., Lee, G., and Tripp, R.B., 2014, Multi-media exploration geochemistry study targeting Cu-Au and Mo resources in the Tyonek quadrangle, Alaska Range, Alaska: Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 250. View Graham 2014 GSA abstract.

Haeussler, P.J., Bradley, D., Ayuso, R., Layer, P.W., Friedman, R.M., O'Sullivan, P., Jones, J.V. III, Karl, S.M., Box, S.E., and Rodd, E., 2013, Magmatic history of the Tordrillo Mountains and the western Alaska Range and tectonic implications: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 77. View Haeussler 2013 GSA abstract.

Jones, J.V. III, Todd, E., Box, S.E., Haeussler, P.J., Holm-Denoma, C.S., Ayuso, R.A., and Bradley, D.C., 2014, Late Cretaceous through Oligocene magmatic and tectonic evolution of the western Alaska Range: Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 781. View Jones 2014 GSA abstract.

Karl, S.M., Box, S.E., Jones, J.V. III, Lease, R.O., Bradley, D.C., Haeussler, P.J., Hults, C.P., and Graham, G., 2013, Petrographic and detrital zircon data from the Kahiltna basin suggest Early Cretaceous juxtaposition of the continental margin and the Peninsular terrane in the western Alaskan Range: Geological Society of America Abstracts with Programs, Vol. 45, No. 7, p. 78. View Karl 2013 GSA abstract.

Karl, S.M., Box, S.E., Lease, R.O., Jones, J.V. III, Holm-Denoma, C., Bradley, D., and Haeussler, P.J., 2015, Formation of the Kahiltna basin, Alaska, by time-transgressive Early to Late Cretaceous dextral-oblique juxtaposition of two independent depositional systems: Geological Society of America Abstracts with Programs, Vol. 47, No. 4, p. 53. View Karl 2015 GSA abstract.

Lease, R.O., Haeussler, P.J., and O'Sullivan, P.B., 2015, Exhumation patterns during Cenozoic growth and glaciation of the Alaska Range: Insight from detrital geo- and thermo-chronology: Geological Society of America Abstracts with Programs, Vol. 47, No. 4, p. 46. View Lease 2015 GSA abstract.

Lease, R.O., Haeussler, P.J., and O'Sullivan, P.B., 2014, Detrital thermochronology of the Alaska Range: Exhumation during Cenozoic subduction and translation: Abstract EP12B-06 presented at 2014 Fall Meeting, AGU, San Francisco, Calif., 15-19 Dec. View Lease 2014 AGU abstract.

Saltus, R.W., Bedrosian, P.A., Jones, J.V. III, Haeussler, P.J., Todd, E., Wilson, F.H., and Stanley, R.G., 2015, Digging into the south Alaska deep magnetic high - Implications of boundary and internal complexities for crustal structure: Geological Society of America Abstracts with Programs, Vol. 47, No. 4, p. 52. View Saltus 2015 GSA abstract.

Saltus, R.W., Jones, J.V. III, Stanley, R.G., Haeussler, P.J., Potter, C.J., and Lewis, K.A., 2014, Reverse/thrust faults in and around Susitna basin, Alaska – Geophysical evidence and structural implications: Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 780. View Saltus 2014 GSA abstract.

Saltus, R., Stanley, R., Lewis, K., and Haeussler, P., 2014, A tilted bed for the sleeping lady? Gravity and magnetic evidence for a thrustfault interpretation of the Mt Susitna/Beluga Mtn front: 2014 Alaska Geological Society Technical Conference, 15-16 May, 2014, Anchorage, AK, p. 8. View AGSTC abstract booklet. [PDF file, 323 KB]

Todd, E., Jones, J.V. III, Box, S.E., Saltus, R., Karl, S.M., and Haeussler, P.J., 2015, Western Alaska Range magmetic response to progressive accretion of the Wrangellia composite terrane and evolution of the southern Alaska margin: Geological Society of America Abstracts with Programs, Vol. 47, No. 4, p. 53. View Todd 2015 GSA abstract.

Todd, E., Jones, J.V. III, Karl, S., Ayuso, R.A., Bradley, D.C., Box, S.E., and Haeussler, P.J., 2014, Magmatic responses to Late Cretaceous through Oligocene tectonic evolution of the western Alaska Range: Abstract V32B-06 presented at 2014 Fall Meeting, AGU, San Francisco, Calif., 15-19 Dec. View Todd 2014 AGU abstract.

Todd, E., Jones, J., Karl, S., Ayuso, R., Stelten, S., Saltus, R., Box, S., Bradley, D., Haeussler, P., and Gamble, B., 2014, Geochemistry and tectonic significance of pluton successions in the western Alaska Range: Goldschmidt Abstracts, p. 2492. View Todd 2014 Goldschmidt abstract.

Project Contact

Peter Haeussler
Phone: 907-786-7447
Email: pheuslr@usgs.gov
Alaska Science Center

Mineral Resources Program Science Priority

The use of firm, trade, and brand names is for identification purposes only and does not constitute endorsement by the U.S. government.

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