Skip to main content
Skip to main content

Overview

quartz vein in Alaska
Half-meter-thick quartz veins cut across outcrops of granitic gneiss on Divide Mountain along the Alaska-Yukon border, August 2015. Photo by J. Jones III, USGS.

The Yukon-Tanana terrane, stretching from eastern Alaska to northern British Columbia, is a geologically complex block containing deposits of base-metal, platinum-group-element, and gold-silver-copper mineralization. However, geologic and exploration models for these deposits are limited by a lack of data regarding the individual deposits, their tectonic settings, and the genetic processes critical to their formation. Unraveling the history of this terrane is essential for assessing the extent and distribution of that mineralization and for understanding the geologic factors controlling deposit formation. This project brings together scientists from both sides of the Alaska-Canada border to develop a coherent model for the geologic evolution of the Yukon-Tanana block and provide a much-needed context for more focused studies and mineral exploration within the terrane.

This project builds on the work of a previous investigation, Alaska/Yukon Geophysical/Geological Reconciliation of the Pericratonic Yukon-Tanana Terrane, which focused on reconciling the various interpretations in mapping of geologic and geophysical trends across the Alaska-Yukon border. Geophysical features maps were developed to allow for the delineation of subsurface features, structures, and domains across the Alaska/Yukon border. These maps then served as a platform for a cross-border regional synthesis which integrated geologic mapping, geophysical data, structural analyses, geochemistry, and age-dating analyses.

Top

Current Activities

helicopter landing, Alaska
Helicopter landing to pick up field personnel after a day of geologic mapping and sampling in the Fortymile region north of Tok, Alaska. Photo by J. Jones III, USGS.

Geologic Framework

Contact: James V. Jones III, jvjones@usgs.gov

Geologic framework studies will focus on the characterization of rocks exposed in the Tanacross quadrangle of eastern Alaska and in surrounding regions. Research will include igneous, metamorphic, structural, and thermochronologic studies. In addition to new field mapping and sampling, selected legacy samples in the USGS rock archive will be re-analyzed. These investigations will allow the researcher to highlight the geology and structures favorable for permissive metallic-mineral-resource discovery.

Geophysical Framework

Contact: Jonathan Caine, jscaine@usgs.gov

Geophysical framework studies will combine existing regional data with new airborne geophysical data that spans the international border. Preliminary results will be refined and tested with new geologic mapping and observation. Geophysical interpretations will be compared to known mineral occurrences and will aid in understanding the controls and loci of metallogenetic events and their association with metamorphic and magmatic events.

Metallogenic Framework

Contact: Garth Graham, ggraham@usgs.gov

Metallogenic framework studies will focus on mineral occurrences and deposits in the study area and how they compare to deposits in districts both east (Klondike-White Gold, Yukon) and west (Fairbanks, Alaska). Gold resource tracts in east-central Alaska will be delineated, and gold deposit types will be defined. Detailed studies of known lodes on both sides of the Alaska-Yukon border will be combined with placer fingerprint studies in an attempt to relate placer accumulations to specific lodes based on the physical and chemical features of the gold in both occurrences.

Regional Studies

Contact: Cynthia Dusel-Bacon, cdusel@usgs.gov

Publish reports that will contribute to clarifying the regional geologic framework of east-central Alaska by summarizing previous research on the Mesozoic and Cenozoic geologic history of the region.

Top

Completed Activities

Alaska/Yukon Geophysical/Geological Reconciliation of the Pericratonic Yukon-Tanana Terrane

Previous activities in the area focused on geophysical mapping, geophysical and geological integration, and integrated interpretation by using new geophysical maps to facilitate cross-border geologic mapping, key units, assemblages, and structures that are present on both sides of the Alaska-Yukon border. USGS scientists worked together with the Alaska Division of Geological and Geophysical Surveys, the Yukon Geological Survey, and the Geological Survey of Canada to reconcile their differing perspectives on the geologic and geophysical data into a coherent model for the geologic evolution of the Yukon-Tanana block.

geologist on Alaskan outcrop
USGS scientist examining outcrops of strongly deformed and metamorphosed rock along Divide Mountain in the Yukon-Tanana upland of eastern Alaska. Photo by J. Jones III, Alaska.
scientists digging through tundra to sample rock
USGS scientist digging through tundra in hopes of finding bedrock to sample for geochemistry and geochronology, Yukon-Tanana upland, eastern Alaska. Photo by J. Jones III, USGS.

Top

Products

Journal Articles and Reports

Apatite fission-track evidence for regional exhumation in the subtropical Eocene, block faulting, and localized fluid flow in east-central Alaska
(January 2016)
Cynthia Dusel-Bacon, C.R. Bacon, P.B. O'Sullivan, and W.C. Day, 2016, Canadian Journal of Earth Sciences, 53(3), p. 260-280, http://dx.doi.org/10.1139/cjes-2015-0138.

Airborne magnetic geophysical survey of the Tanacross region, Alaska
(October 2015)
A.M. Emond, R.W. Saltus, G. Graham, and Goldak Airborne Surveys, 2015, Alaska Division of Geological & Geophysical Surveys Geophysical Report 2015-6, http://dx.doi.org/10.14509/29514

Alaska and Yukon Magnetic Compilation—Residual Total Magnetic Field
(May 2015)
W. Miles, R.W. Saltus, N. Hayward, and D. Oneschuk, 2015, Geological Survey of Canada Open-File 7862, scale 1:1,120,000, 1 sheet, http://dx.doi.org/10.4095/296589.

Mesozoic magmatism and timing of epigenetic Pb-Zn-Ag mineralization in the western Fortymile mining district, east-central Alaska—Zircon U-Pb geochronology, whole-rock geochemistry, and Pb isotopes
(May 2015)
C. Dusel-Bacon, J.N. Aleinikoff, W.C. Day, and J.K. Mortensen, 2015, Geosphere, 11(3), p. 786-822, http://dx.doi.org/10.1130/GES01092.1.

The Late Cretaceous Middle Fork caldera, its resurgent intrusion, and enduring landscape stability in east-central Alaska
(November, 2014)
C.R. Bacon, C. Dusel-Bacon, J.N. Aleinikoff, and J.F. Slack, 2014, Geosphere, v. 10, p. 1432-1455, http://dx.doi.org/10.1130/GES01037.1.

Geologic map of the Kechumstuk fault zone in the Mount Veta area, Fortymile mining district, east-central Alaska
(March 2014)
W.C. Day, J.M. O’Neill, C. Dusel-Bacon, J.N. Aleinikoff, and C.R. Siron, C.R., 2014, U.S. Geological Survey Scientific Investigations Map 3291, scale 1:63,360, http://dx.doi.org/10.3133/sim3291.

Tackling “Boundary Faults” Across the Alaska-Yukon Border—A Report from the Field
(October 2013)
R.W. Saltus, 2013, Earth Magazine, 58(10), p. 8–9, http://www.earthmagazine.org/article/tackling-boundary-faults-across-alaska-yukon-border-report-field.

Abstracts

Using detrital zircon to correlate and reconstruct Neoproterozoic and early Paleozoic components of peri-Laurentian terranes in the northern Cordillera and Alaska
(November 2015)
J.V. Jones III, C.S. Holm-Denoma, and P.B. O'Sullivan, 2015, Geological Society of America Abstracts with Programs, v. 47, no. 7, p. 860. View Jones 2015 GSA abstract 1.

Refining the characteristics, age, and extent of the Permian Klondike assemblage in eastern Alaska
(August 2015)
J.V. Jones III, Dawson Rocks Conference, August 2015, Dawson City, YT, Canada.

A fault rock record of Late Eocene strain partitioning along the Denali fault zone in southwestern Yukon
(May 2015)
J.S. Caine, S.A. Israel, D.C. Murphy, and J. Benowitz, 2015, Geological Society of America Abstracts with Programs, v. 47, no. 4, p. 51. View Caine 2015 GSA abstract.

Refining the characteristics, age, and extent of the Permian Klondike assemblage in eastern Alaska
(May 2015)
J.V. Jones III, J.S. Caine, C.S. Holm-Denoma, R.O. Lease, R.W. Saltus, and E. Todd, 2015, Geological Society of America Abstracts with Programs, v. 47, no. 4, p. 18. View Jones 2015 GSA abstract 2.

Alaska–Yukon geophysical basement domains from new magnetic data compilation
(May 2015)
R.W. Saltus, D.C. Murphy, N. Hayward, J.V. Jones III, J.S. Caine, and M. Colpron, 2015, Geological Society of America Abstracts with Programs, v. 47, no. 4, p. 17. View Saltus 2015 GSA abstract.

Reconciling contrasting geologic interpretations across the Alaska-Yukon border: implications for regional framework geology and metallogeny
(November 2014)
J.V. Jones III, J.S. Caine, C.S. Holm-Denoma, R.O. Lease, and E. Todd, 2014, Alaska Miners Association 2014 Annual Meeting, November 3-9, 2014, Anchorage, AK.

Bedrock geology, internal structure, kinematics, and carbonaceous fault rocks of the Denali fault zone at Telluride and Kimberly Creeks, southwest Yukon, Canada
(October 2014)
J.S. Caine, D.C. Murphy, and S.A. Israel, 2013, Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 28. View Caine 2014 GSA abstract.

Apatite fission track evidence of widespread Eocene exhumation in the Fortymile District of east-central Alaska
(October 2014)
C. Dusel-Bacon, P.B. O'Sullivan, W.C. day, and C.R. Bacon, 2013, Geological Society of America Abstracts with Programs, Vol. 46, No. 6, p. 794. View Dusel-Bacon 2014 GSA abstract.

Nature and U-Pb zircon ages of mid-Cretaceous calderas and tuffs in eastern Alaska and western Yukon: Implications for landscape evolution in the northern Cordillera
(October 2014)
J.K. Mortensen and C. Dusel-Bacon, 2014, Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p. 794. View Mortensen 2014 GSA abstract.

Denali damage—Bedrock deformation, kinematics, and fluid flow in the brittle regime along the Denali Fault Zone, Kluane Lake, Yukon Territory, Canada
(October 2013)
J.S. Caine, S.A. Israel, K.R. Sicard, and C.P. Hults, 2013, Geological Society of America Abstracts with Programs, v. 45, no. 7, p. 78. View Caine 2013 GSA abstract.

Mesozoic framework for magmatism, metallogeny, and faulting in the western Fortymile Mining District, east central Alaska—SHRIMP U-Pb zircon geochronology, whole-rock geochemistry, and lead isotopes
(October 2013)
C. Dusel-Bacon, J.N. Aleinikoff, W.C. Day, and J.K. Mortensen, 2013, Geological Society of America Abstracts with Programs, v. 45, no. 7, p. 78. View Dusel-Bacon 2013 GSA abstract.

Reconciling geology between Alaska and the Yukon – Potential role of regional magnetic anomaly data
(October 2013)
R.W. Saltus, N. Hayward, J.V. Jones III, and D.C. Murphy, 2013, Geological Society of America Abstracts with Programs, v. 45, no. 7, p. 78. View Saltus 2013 GSA abstract.

Top

Project Contacts

Project Chief: James V. Jones III
Phone: 907-786-7442
Email: jvjones@usgs.gov
Profile: http://profile.usgs.gov/jvjones
Alaska Science Center

Associate Project Chief: Garth Graham
Phone: 303-236-1558
Email: ggraham@usgs.gov
Central Mineral and Environmental Resources 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.

Download if needed: Excel Viewer | PDF Reader | Powerpoint Viewer | Word Viewer