Filters: Contacts: Solie, D.N. (X)
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Twenty-two igneous and metamorphic rock samples were collected in a 20-km-long swath centered on the Alaska Highway between Tetlin Junction, Alaska, and the Canada border. Igneous and metamorphic rock samples were submitted to the Apatite to Zircon, Inc. laboratory (A2Z), where zircon U-Pb age analysis, using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), was performed by Paul O'Sullivan. The 15 felsic plutonic rock samples and one gabbro sample yield Cretaceous zircon U-Pb weighted-mean ages ranging from 95.7 Ma to 106.2 Ma. Zircons from a metadiorite yield a Triassic weighted-mean age of about 241.9 Ma. Metamorphic zircons from two samples with felsic igneous protoliths yield Mississippian...
In 2006-2007, Alaska Division of Geological & Geophysical Surveys (DGGS) geologists traversed and collected rock samples from ridges on the north side of Granite Mountain in the Mount Hayes D-3 Quadrangle to supplement existing literature with additional details about the variations in texture, lithology and orientation of the 'Granite of Granite Mountain' (map unit grgm) described by Nokleberg and others (1992). The digital data files for this report provide station locations and observations recorded in the geologists' field notes. Outcrop observations describe fine- to medium-grained granodiorite and medium- to coarse-grained tonalite units which appear to be in contact with each other on the ridges north of...
Geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) and the University of Alaska Fairbanks (UAF) carried out geologic field surveys, including bedrock mapping and sampling, in the Alaska Highway Corridor from 2006 through 2010. The fieldwork provides basic information critical to building an understanding of Alaska's geology and is part of a broader, integrated program that includes airborne geophysical surveys, bedrock and surficial mapping, a mineral-resource assessment, a geologic-hazards assessment, and other geological studies. This publication contains descriptive, location, and analytical information for samples collected in the Mount Hayes, Tanacross, and Nabesna quadrangles, Alaska,...
Alaska Division of Geological & Geophysical Surveys (DGGS) personnel collected rock samples while mapping the bedrock geology along a 12-mile-wide swath following the Alaska Highway between Delta Junction and the eastern edge of the Mount Hayes quadrangle near Dot Lake, Alaska. This mapping is one component of the multi-year DGGS project studying the geology, geohazards and resources along the proposed gas pipeline corridor from Delta Junction to the Canadian border. In 2006, we collected 10 samples for whole rock (major- and minor-oxides, and petrogenetically important trace-elements) analysis. In 2007, we collected 111 samples for whole rock analysis and 36 rock samples for geochemical trace-element analysis....
This report provides detailed (1:63,360-scale) mapping of portions of U.S. Geological Survey Circle B-2 (1955), B-3 (1955), B-4 (1952), C-2 (1955), C-3 (1955), and C-4 (1952) quadrangles. The area is part of the Circle mining district and adjacent to the Fairbanks mining district. This report includes detailed geologic, structural, stratigraphic, and geochronologic data. Based on the resulting geologic maps, field investigations, and laboratory materials analyses, the project has also generated derivative maps of geologic construction materials and geologic hazards.
This preliminary geologic map of the Fairbanks mining district was mapped at 1:63,360 scale. The report describes the geologic setting, structural geology, earthquake potential, economic geology and the description of bedrock units.
Naturally occurring asbestos (NOA) develops in predictable geologic settings worldwide. Various geologic units throughout Alaska include rock types that could potentially host naturally occurring asbestos minerals. This report and digital data release show geologic map units throughout Alaska rated according to their interpreted potential to host NOA. To summarize locations of known asbestos occurrences, we searched the U.S. Geological Survey's (USGS's) Alaska Resource Data File (http://ardf.wr.usgs.gov) and Mineral Resource Data System (http://mrdata.usgs.gov/mineral-resources/mrds-ak.html) for references to asbestos in Alaska and compiled the resulting 62 documented asbestos occurrences. To better predict additional...
40Ar/39Ar data from plutonic and volcanic samples collected during preliminary mapping of the Tyonek D-6 and parts of Tyonek D-5, D-7 and C-6 quadrangles yield results indicating three discrete igneous events at about 55, 60 and 68 Ma. Igneous clasts from a boulder conglomerate retain Early Cretaceous ages.
In support of the proposed Susitna-Watana Hydroelectric Project, the Alaska Division of Geological & Geophysical Surveys (DGGS) developed a Geographic Information System (GIS)-based geologic compilation of published and unpublished maps for twelve, inch-to-mile (1:63,360-scale) quadrangles encompassing the proposed hydroelectric project footprint, including the anticipated reservoir and surrounding area. DGGS geologists reviewed and analyzed existing geologic mapping for quality and completeness, and the maps were converted for use in GIS. The conversion process included scanning and georeferencing the original hard-copy map documents, creating a geodatabase, digitizing the geologic data, assigning attributes, and...
40Ar/39Ar data from seven plutonic samples and one metamorphic sample collected during mineral assessment studies in 1991 show that various rock units in the Selawik Hills plutonic complex were emplaced in the order syenite/monzonite (nonfoliated, 106.6 ± 0.8 Ma; foliated, 101.7 ± 0.7 Ma; both on hornblende), followed by nepheline syenite (103.7 ± 0.8 Ma on hornblende) and then quartz monzonite (100.4 ± 3.7 Ma on biotite). 40Ar/39Ar data from Granite Mountain hornblendes yielded ages slightly older, but overlapping, those from Selawik Hills. In this suite, the silica-undersaturated phase appears to be younger (105.7 ±0.8 Ma) than the silica-saturated phase(s) (106.8 ± 0.8 Ma and 107.1 ± 0.8 Ma).
During 2006 and 2007 the Alaska Division of Geological & Geophysical Surveys conducted reconnaissance interpretive mapping of permafrost in Alaska Highway Corridor Segment 1, which straddles the Alaska Highway through the Tanana River valley from Delta Junction to the eastern boundary of the Mt. Hayes Quadrangle. Primarily, we inferred the extent of permafrost and ice content by interpreting ~1:63,360-scale, false-color infrared aerial photographs taken in August 1980.
40Ar/39Ar analyses of igneous rocks from the Alaska Highway corridor between Delta Junction and the Canada border show a range of Cretaceous ages from about 68 Ma to about 112 Ma. The 25 samples fall into two broad age groups. The younger group ranges from about 68 Ma to 73 Ma; the older group ranges from a minimum age of about 84 Ma to about 103 Ma. One sample, a mafic dike, yielded an older age of about 112 Ma.
During 2006 and 2007 the Alaska Division of Geological & Geophysical Surveys conducted reconnaissance surficial-geologic mapping in segment 1 of the Alaska Highway corridor, which straddles the Alaska Highway through the Tanana River valley from Delta Junction to the eastern boundary of the Mt. Hayes Quadrangle. Surficial-geologic deposits were initially mapped by interpreting ~1:63,360-scale, false-color infrared aerial photographs taken in August 1980 and field verified in 2006-2007.
The engineering-geologic map, on two sheets, is derived electronically from the surficial-geologic map of the initial segment of the proposed natural gas pipeline corridor through the upper Tanana valley (Reger and others, PIR 2008-3a) using Geographic Information System (GIS) software. Surficial-geologic units were initially identified by interpretation of false-color ~1:63,000-scale infrared aerial photographs taken in July 1978, August 1980, and August 1981 and locally verified by field checking in 2006 and 2007. The map shows the distribution of surficial-geologic and bedrock units grouped genetically with common properties that are typically significant for engineering applications.
During the 2006 and 2007 field seasons, geologic features indicative of possible youthful surface faulting in or near the Alaska Highway corridor between Delta Junction and Dot Lake were identified by helicopter and fixed-wing air reconnaissance, augmented by interpretation of stereo air photos, remotely sensed images, and aeromagnetic and electromagnetic (EM) datanction to the eastern boundary of the Mt. Hayes Quadrangle. The largest of these faults is the previously unrecognized Dot "T" Johnson fault, a major west-trending, south-dipping thrust fault bordering the northern margin of the Alaska Range along the south side of the Tanana River valley. Two other faults identified as active in this study, the Canteen...
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