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What's new in Alaska? Small shaded relief image of Alaska.

by Judy Back, Bruce Gamble, Larry Gough, Susan Karl, Karen Kelley, Jeanine Schmidt, Nora Shew, Frederic Wilson, and Dwight Bradley

Contents: New directions || Completed work || Continuing work || More information

In April, 2002, the U.S. Geological Survey (USGS) opened its Alaska Science Center in Anchorage. The purpose of the center is provide greater focus on the wide array of USGS work being conducted in the State. USGS work in Alaska examines biologic, geologic, geographic, and water resources as well as geologic hazards such as earthquakes and volcanoes. The USGS Mineral Resources Program will continue its long history of studying the mineral resources of Alaska under the auspices of the new Center. Here is what we are doing:

New directions

Two new one-year projects are beginning this fall are aimed at determining future USGS mineral-related research in Alaska.

Future directions for minerals in Alaska

As a member of the Alaska Interagency Minerals Coordinating Group, the USGS has been coordinating its mineral-related work in Alaska with the Bureau of Land Management, the U.S. Forest Service, and the Alaska Division of Geological and Geophysical Surveys since 1996. This fall, the USGS will solicit input from its partners in the coordinating group, from Native Corporations, and nongovernmental organizations to help determine the highest priority minerals issues facing Alaska during the next few years (2004-2008). The USGS Mineral Resources Program will use the resulting recommendations to help shape future work in Alaska.

For more information, please contact:
Bruce Gamble
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
bgamble@usgs.gov
907-786-7479

Mineral potential of southeastern Alaska

The goal of this project is to consult with regional, local, and topical experts, clients, and potential collaborators to help develop an updated understanding of mineral potential in southeastern Alaska, prioritize future work in the region, and create a long-range plan to accomplish this work. This fall, we will consult with the State of Alaska, the Bureau of Land Management, the U.S. Forest Service, the Sealaska Native Corporation, and local communities to ensure that plans for future USGS mineral investigations in southeastern Alaska are relevant to land management priorities, biological concerns, environmental concerns and impacts, and local economies. Within the last few years, significant new data (geologic mapping, geophysical data, geochemistry, isotopic analyses, geochronology, paleontology, and structural analyses) have been collected, and significant advances have been made in our understanding of ore genesis, host-rock characteristics, and element ratios associated with various commodities. This project will begin compiling new and old data into digital coverages and interpreting those data in light of recent advances in knowledge of sources and deposition of mineral deposits of current economic importance.

For more information, please contact:
Susan Karl
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
skarl@usgs.gov
(907)786-7428

Two other new projects will begin this fall:

Tintina metallogenic province integrated studies on geologic framework, mineral resources, and environmental signatures

A new project in Tintina will study the origin of mineral resources in the province, controls on emplacement, and environmental consequences related to development of these resources. This arcuate, 1,200-kilometer-long metallogenic province extends from northern British Columbia to southwestern Alaska. In addition to hosting large deposits of vein golds and volcanic massive sulfides, the province is an important region within the State for large public-works programs such as a proposed trans-Alaskan natural gas pipeline and infrastructure for the Strategic Missile-Defense System.

For more information, please contact:
Larry Gough
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
lgough@usgs.gov
907-786-7441

Regional fluid flow and basin modeling of northern Alaska

Research recently completed at Red Dog in northern Alaska determined that the scale of fluid flow and flux of metals in the sedimentary basins was vast, perhaps of long duration, and that there may have been a temporal overlap between fluid migration and hydrocarbon generation. The new regional flow project is being launched to study the interaction of ore-forming and petroleum-generating processes in order to improve our understanding of the role of fluid migration and contribute to more effective assessments of resources in sedimentary basins of northern Alaska and elsewhere in the world. The goal of the project will be to construct quantitative physical models of the Carboniferous to Cretaceous basins now found in the deformed rocks of the Brooks Range. The models will result in an improved knowledge of long-term sedimentation patterns, thermal maturation, evolution of fluids generated in the basins, the migration pathways of the fluids, and prediction of the sites of mineral and petroleum accumulation.

For more information, please contact:
Karen Duttweiler Kelley
U.S. Geological Survey
Box 25046, MS 964
Denver, Colorado 80225
kdkelley@usgs.gov
(303) 236-2467

Completed work

Syngenetic massive sulfide deposits in Alaska

USGS research into syngenetic massive sulfide deposits in Alaska is now completed. The project focused on three metallogenic provinces that contain volcanogenic and (or) sedimentary-hosted massive sulfide deposits: (1) the world's largest known zinc deposit at Red Dog; (2) the giant Greens Creek deposit hosted in Upper Triassic rocks of southeastern Alaska and Canada; and (3) Zn-Pb occurrences and deposits in middle and lower Paleozoic rocks of east-central Alaska. The objectives of the project were to better understand the mechanisms and timing of sulfide deposition, the sources of ore-forming metals and fluids, and controls on ore-fluid migration. In addition to specific papers on east-central Alaska published by the USGS and in outside publications, two primary products include a USGS Professional Paper on the work done at the Greens Creek deposit (in press) and a special issue of Economic Geology on the Red Dog district (papers in progress, due in print in early 2004).

For more information, please contact:
Karen Duttweiler Kelley
U.S. Geological Survey
Box 25046, MS 964
Denver, Colorado 80225
kdkelley@usgs.gov
(303) 236-2467

Continuing work

Early Tertiary slab window in Alaska and its resource implications

This project is testing the hypothesis that ridge subduction can explain much of the Late Cretaceous to early Tertiary geology of and mineral deposits in Alaska. The project is investigating many of the geologic corollaries of the ridge subduction hypothesis and the idea that an asthenosphere slab window opened at depth between the subducted plates and had widespread geologic effects as far as 1,000 kilometers inland. Work is focused on Upper Cretaceous and lower Tertiary rocks (80 to 40 Ma) in Alaska, but some of the work is the examining effects of a related slab window in western Canada and the western United States. The may provide a single rationale for a vast amount of geologic data covering much of Alaska, the Yukon, British Columbia, Washington, and Oregon. The postulated slab window may have been responsible for the genesis of several ore deposit types, basin development in the interior of Alaska, and hydrocarbon migration on the North Slope - phenomena that have been interpreted only on a case-by-case basis.

For more information, please contact:
Dwight Bradley
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
dbradley@usgs.gov
907-786-7434

Biogeochemical and biochemical pathway investigations of cadmium in Arctic and subarctic ecosystems using an accumulator species (willow)

Biogeochemical investigations are being conducted on the pathways that control cadmium transport and uptake by vegetation over mineralized and nonmineralized terranes in Arctic and subarctic ecosystems. The connection of high levels of cadmium in willow to adverse animal health, under natural conditions, was recently demonstrated by Larison and others (2000; Gough and others, 2002). There are no data on the possible adverse health effects of high bioavailable cadmium levels in native browse species in Alaska. We are working with the Alaska Department of Fish and Game to assess the relative importance of cadmium concentrations in willow to the health of browsing animals (moose, ptarmigan, and beaver. The biogeochemistry of cadmium within willow is being investigated by using plantation-grown specimens followed by examination of plant extracts at the Stanford Synchrotron Radiation Laboratory.

Photograph of leaf and stem material of plantation-grown willow plants that were given a nutrient solution spiked with cadmium-nitrate plus salicylate.
Leaf and stem material of plantation-grown willow plants that were grown in a nutrient solution spiked with cadmium-nitrate plus salicylate. Extracts will be examined at the Stanford Synchrotron Radiation laboratory.

References:

Gough, L.P., Sanzolone, R.F., Crock, J.G., Foster, A.L., Lamothe, P.J., Ager, C.M., and Gent, C.A., 2002, Biogeochemical and biochemical pathway investigations of cadmium in subarctic ecosystems using a cadmium accumulator species (willow), chapter 4, in Balistrieri, L.S. and Stillings, L.L., eds., Pathways of metal transfer from mineralized sources to bioreceptors-a synthesis of the Mineral Resources Program's past environmental studies in the western United States and future research directions: U.S. Geological Survey Bulletin 2191, 11 p. (http://geopubs.wr.usgs.gov/bulletin/b2191/).

Larison, J.R., Likens, G.E., Fitzpatrick, J.W., and Crock, J.G., 2000, Cadmium toxicity among wildlife in the Colorado Rocky Mountains: Nature, v. 406, p. 181-183.

For more information, please contact:
Larry Gough
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
lgough@usgs.gov
907-786-7441

Talkeetna Mountains transect

The Talkeetna Mountains project enters its final year in 2003. The overall objective of the project is to understand the geology and tectonic assembly of the Talkeetna Mountains in order to accurately assess its mineral potential. The Talkeetna Mountains are key to reconstructing the complex Triassic to Tertiary tectonic history and mineral potential (tin, molybdenum, silver, gold, copper, nickel, and platinum-group element deposits) of south-central Alaska. Results of this study have already shown that rocks previously considered Paleozoic in age are Triassic flood basalts and may be associated with rocks having high potential for nickel, copper, and platinum-group element deposits and that young volcanic rocks associated with gold anomalies are more extensive than previously thought in the northern Talkeetna Mountains and may indicate significant potential for gold deposits at depth.

Photograph of geologist pointing to an internal contact within tin-gold bearing granites in the distance.
USGS geologist Peter Oswald, points to an internal contact within the 58 million-year-old Sn-Ag bearing granites.

Photograph of pillow basalts that may be related to magmas that host nickel, copper, and platinum-group element deposits to the east.
USGS geologists Brian Hampton and Peter Oswald (lower part of photo) examine pillow basalts of suspected Triassic age to determine a stratigraphic up position. These basalts are probably related to the magmas that host Ni, Cu and PGE deposits to the east.

For more information, please contact:
Jeanine Schmidt
4200 University Drive
Anchorage, Alaska 99508
jschmidt@usgs.gov
907-786-7494

Much of our continuing work is related to data recovery and to developing, maintaining, and updating the content of geological, geochemical, geophysical, and mineral deposits databases for Alaska.

Surveys and Analyses project

This work is part of a national effort to compile nationally standardized digital geologic, geophysical, geochemical, and mineral deposits databases and collect new data where necessary. The national effort was reported on in the first issue of this newsletter (http://minerals.usgs.gov/news/newsletter/v1n1/A3.html).

  • Geology: The project is working on compiling an integrated, up-to-date, digital geologic map of Alaska. Significant new geologic mapping is being incorporated into this effort.
  • Geophysics: The project is working on Statewide compilation, synthesis, and regional analysis of geophysical information and currently is focusing on finalizing gravity and magnetotelluric databases, creating a geophysical rock property database, and preparing a regional framework for interpretation of these geophysical data.
  • Geochemistry: The project is working to compile a geochemical synthesis of Alaska that will be useful in determining regional backgrounds, differentiating between similar geologic units, and determining regional evolution or trends of mineral deposit geochemistry. Synthesizing existing geochemical data is a difficult task because the data for Alaska are very unevenly distributed and vary considerably in quality. Efforts are concentrating on evaluating various statistical and data manipulation methods to define the characteristic variables for distinguishing sampling plus analytical variance from geologic variance and to investigate the parameters for integrating separate databases into coherent regional data sets.
  • Mineral deposits information: The Alaska Resource Data File (see Data-at-risk project below) of mineral deposits is being updated, largely through contracts with local geologists. The Alaska Resource Data File is on the Web at: http://ardf.wr.usgs.gov/welcome.html.

For more information about these efforts, please contact:
Frederic Wilson
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
fwilson@usgs.gov
907-786-7448

Alaska data at risk

Work continues to locate, cleanup, collate, and make publicly available geologic- and minerals-related data for Alaska. The USGS is directly responsible for geochemical (please see related article in this issue on the National Geochemical Database for more information about the individual databases, http://minerals.usgs.gov/news/newsletter/v1n2/2geochem.html), mineral deposit, and bibliographic databases.

  • Geochemical data: We have completed work on Alaska non-rock data in the Rock Analysis Storage System (RASS) database. Non-rock data from the PLUTO (named for the god of the underworld from classical mythology) database will be completed by the end of this year. RASS data are available on-line at: http://pubs.usgs.gov/of/1999/of99-433/.
  • Mineral deposit data: The Alaska Resource Data Files are being systematically updated and recompiled by 1:250,000 quadrangle. Data were last compiled in the late 1970s and early 1980s, and much exploration and mining has occurred since then. For each quadrangle, the USGS is contracting with independent geologists who have experience in the region to update the database. Ninety-four of the 118 1:250,000-scale quadrangles in Alaska with known mineral occurrences have been completed and are posted on the Web at: http://ardf.wr.usgs.gov/welcome.html. The remaining 24 quadrangles are in the process of being updated.
  • Bibliographic data: The American Geologic Institute's GeoRef database for Alaskan references was obtained and converted to a key-word searchable database. Efforts are underway to post this database on our internet site. When it is posted on the Web, the bibliography will be linked to: http://alaskaminerals.wr.usgs.gov/

For more information, please contact:
Bruce Gamble
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
bgamble@usgs.gov
907-786-7479

Geographic information system (GIS) support

This project provides GIS support and analyses for USGS Alaska-based mineral studies.

For more information, please contact:
Nora Shew
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
nshew@usgs.gov
907-786-7445

For more information

Mineral-related work in Alaska, please contact:
Bruce Gamble
U.S. Geological Survey
4200 University Drive
Anchorage, Alaska 99508
bgamble@usgs.gov
907-786-7479

Alaska Science Center, please contact:
William Seitz, Center Director
U.S. Geological Survey
1011 East Tudor Road
Anchorage, Alaska 99503
William_seitz@usgs.gov
907-786-3345

or, visit the Center's Web site: http://alaska.usgs.gov/



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