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The engineering-geologic map is derived electronically, using Geographic Information System (GIS) software, from the surficial-geologic map of the second segment of the proposed natural gas pipeline corridor through the upper Tanana valley, a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway through the upper Tanana River valley from the Robertson River eastward to near Tetlin Junction in the Tanacross Quadrangle (Reger and Hubbard, PIR 2009-6A). Surficial-geologic units were initially identified by interpretation of false-color ~1:65,000-scale infrared aerial photographs taken in July 1978, August 1980, and August 1981 and locally verified by field checking in 2007 and 2008. The map shows the distribution...
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The Tok project area is adjacent to the Delta mineral belt volcanogenic massive-sulfide (VMS) district, the Peak gold-silver-copper skarn, and structurally controlled gold and antimony mineralization in the Stibnite Creek and White Gold areas. The project area also includes the Noah prospect, an intrusion-related copper prospect. Whereas the Delta mineral belt has been extensively mapped and explored, the detailed mapping does not continue into the 2015 Tok project area. In this area, only reconnaissance mapping has been conducted. The combination of a lack of detailed mapping, the industry interest in the adjacent areas, and the geophysical data findings prompted the Alaska Division of Geological & Geophysical...
Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected...
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Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected...
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During 2008-2010, the Alaska Division of Geological & Geophysical Surveys continued a program, begun in 2006, of reconnaissance mapping of surficial geology in the proposed natural-gas pipeline corridor through the upper Tanana River valley, a 12-mi-wide (19.3-km-wide) area that straddles the Alaska Highway through the upper Tanana River valley from the western boundaries of the Tanacross B-6 and C-6 Quadrangles near the mouth of the Robertson River eastward to the eastern boundaries of the Tanacross A-4 and B-4 Quadrangles near Tetlin Junction. Mapping during 2008-2010 in the Tanacross Quadrangle linked with mapping of surficial geology completed in the Big Delta and Mt. Hayes quadrangles in 2006-2007. Surficial...
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In 2005, the Alaska Division of Geological & Geophysical Surveys initiated a multi-year geologic field study focused on a corridor centered along the Alaska Highway between Delta Junction and the Canada border. The purpose of this project is to provide geologic information relevant to a proposed Alaska-Canada natural gas pipeline and other future development in the corridor. The scope of this project includes identification of active faults and characterization of seismic hazards. During the 2008 field season the active fault studies were focused on the central part of the corridor between Dot Lake and Tetlin Junction. Field studies included helicopter and fixed-wing air reconnaissance augmented by interpretation...
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In 2016, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) and University of Alaska Fairbanks carried out a two-part geologic mapping and geochemical sampling project in the Tok River area of the Tanacross A-5 and A-6 quadrangles (June 12-26 and July 8-26). This report provides results of stream-sediment sampling for trace-element geochemistry. An initial suite of sediment samples was collected from streams draining known gold occurrences, including the Stibnite Creek and Noah prospects, and numerous prospects in the White Gold area. These samples were split in half and the two splits were sieved to -200 mesh and -80 mesh, respectively. The splits were then both analyzed to determine...
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Geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) and University of Alaska carried out a two-part geologic mapping and geochemical sampling project in the Tok River area of the Tanacross A-5 and A-6 quadrangles (June 12-26 and July 8-26). The Tok River area is adjacent to the Delta mineral belt volcanogenic massive-sulfide (VMS) district, the Peak gold-silver-copper skarn, and the structurally controlled gold and antimony mineralization in the Stibnite Creek and White Gold areas. The Tok River project area includes the Noah (also called Hona) prospect, an intrusion-related copper prospect. The combination of insufficient detailed geologic mapping, historical and current industry interest...
Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected...
Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected...
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Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (less than 1 m) and deeper (greater than 1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior...
Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected...
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This report presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) geologic mapping project in the Tanacross A-5 and A-6 quadrangles and adjoining areas. Our results indicate the Hona granodiorite pluton intruded the area in the Late Cretaceous between 76 and 71 Ma. We determined Cretaceous metamorphic ages from 126 to 121 Ma for hornblende, biotite, sericite and muscovite from multiple samples of upper greenschist to amphibolite grade rocks. This is consistent with regional argon results that imply this area is in the upper plate of the Yukon Tanana Terrane (Hansen and Dusel-Bacon, 1998). Basaltic andesite dikes...
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During 2008 the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted reconnaissance interpretive mapping of permafrost in Alaska Highway Corridor Segment 2, a 12-mi-wide (19.3-km-wide) corridor that straddles the Alaska Highway through the upper Tanana River valley from the eastern boundary of the Mt. Hayes Quadrangle to the eastern edge of the Tanacross Quadrangle. This work was an extension of permafrost mapping done in Alaska Highway Corridor Segment 1 from Delta Junction to Dot Lake in the Big Delta and Mt. Hayes Quadrangles during 2006-2007. Primarily, we inferred the extent of permafrost and ice content by interpreting ~1:65,000-scale, false-color infrared aerial photographs taken in July 1978,...
Fire can be a significant driver of permafrost change in boreal landscapes, altering the availability of soil carbon and nutrients that have important implications for future climate and ecological succession. However, not all landscapes are equally susceptible to fire-induced change. As fire frequency is expected to increase in the high latitudes, methods to understand the vulnerability and resilience of different landscapes to permafrost degradation are needed. Geophysical and other field observations reveal details of both near-surface (<1 m) and deeper (>1 m) impacts of fire on permafrost along 11 transects that span burned-unburned boundaries in different landscape settings within interior Alaska. Data collected...
    map background search result map search result map Fire impacts on permafrost in Alaska: Geophysical and other field data collected in 2014 Electrical resistivity tomography (ERT) data; Alaska, 2014 Electrical resistivity tomography (ERT) inverted models; Alaska, 2014 Borehole Nuclear Magnetic Resonance Data; Alaska, 2014 Borehole Nuclear Magnetic Resonance Inverted Models; Alaska, 2014 Permafrost Vegetation Observations; Alaska, 2014 Permafrost Soil Measurements; Alaska, 2014 Surficial geology of Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Engineering-geologic map of the Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Reconnaissance interpretation of 1978-1983 permafrost, Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Active and potentially active faults in or near the Alaska Highway corridor, Dot Lake to Tetlin Junction, Alaska Major-oxide and trace-element geochemical data from rocks collected in 2015 in the Tok area, Tanacross A-5, A-6, and parts of adjacent quadrangles, Alaska Major-oxide and trace-element geochemical data from rocks collected in the Tok River area, Tanacross A-5 and A-6 quadrangles, Alaska in 2016 Trace-element geochemical data from stream sediments collected in the Tok River area, Tanacross A-5 and A-6 quadrangles, Alaska in 2016 40Ar/39Ar data from the Tok River area, Tanacross A-5 and A-6 quadrangles and adjoining areas, eastern Alaska Range Trace-element geochemical data from stream sediments collected in the Tok River area, Tanacross A-5 and A-6 quadrangles, Alaska in 2016 40Ar/39Ar data from the Tok River area, Tanacross A-5 and A-6 quadrangles and adjoining areas, eastern Alaska Range Major-oxide and trace-element geochemical data from rocks collected in the Tok River area, Tanacross A-5 and A-6 quadrangles, Alaska in 2016 Major-oxide and trace-element geochemical data from rocks collected in 2015 in the Tok area, Tanacross A-5, A-6, and parts of adjacent quadrangles, Alaska Surficial geology of Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Engineering-geologic map of the Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Reconnaissance interpretation of 1978-1983 permafrost, Alaska Highway Corridor, Robertson River to Tetlin Junction, Alaska Active and potentially active faults in or near the Alaska Highway corridor, Dot Lake to Tetlin Junction, Alaska Fire impacts on permafrost in Alaska: Geophysical and other field data collected in 2014 Electrical resistivity tomography (ERT) data; Alaska, 2014 Electrical resistivity tomography (ERT) inverted models; Alaska, 2014 Borehole Nuclear Magnetic Resonance Data; Alaska, 2014 Borehole Nuclear Magnetic Resonance Inverted Models; Alaska, 2014 Permafrost Vegetation Observations; Alaska, 2014 Permafrost Soil Measurements; Alaska, 2014