Northeast Tanacross geologic map and map units and descriptions

Wypych, AlicjaHubbard, T.D.Naibert, T.J.Athey, J.E.Newberry, R.J.Sicard, K.R.Twelker, EvanWerdon, M.B.Willingham, A.L.Wyatt, W.C.Lockett, A.C.2021Northeast Tanacross geologic map and map units and descriptionsgeodatabaseReport of InvestigationRI 2020-9BFairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveysp. 9-26, 1 sheet, scale 1:63,360https://doi.org/10.14509/30539Report of Investigation 2020-9B, Northeast Tanacross geologic map and map units and descriptions, provides 500 square miles of 1:63,360-scale geologic mapping in the northeastern Tanacross Quadrangle (Tanacross D-1, and parts of the C-1, C-2, and D-2 quadrangles), located 15 miles southeast of Chicken, Alaska. The project took place during two periods: a reconnaissance mapping effort June 12-22, 2017, and a detailed campaign June 18-July 16, 2018. The map area covers the boundary between the allochthonous Yukon-Tanana terrane (YTT) and the parautochthonous North American margin (pNA) from which the YTT initially rifted. This suture zone has a complex, multiphase structural and metamorphic history, and the northeastern Tanacross Quadrangle is one of the rare areas in which it is exposed. The conceptual framework has been developed in the literature, but it is not fully represented in previously published geologic maps of eastern Alaska. This map encompasses an area of current mineral industry interest; it includes the Taurus porphyry copper-gold-molybdenum +/- rhenium deposit and several other occurrence types, including gold, copper, and molybdenum in porphyritic intrusions, structurally controlled silver-lead-zinc prospects, and placer gold deposits. The complete report, geodatabase, and ESRI fonts and style files are available from the DGGS website: http://doi.org/10.14509/30539.Resurgent mineral industry interest in the East central Alaska region prompted DGGS to conduct new 1:63,360-scale geologic mapping in the northeastern Tanacross Quadrangle.This geodatabase is organized according to the AK GeMS mapping schema Hendricks, M.D., Ekberg, P.G., Athey, J.E., Wyatt, W.C., Willingham, A.L., and Naibert, T.J., 2021, AK GeMS data dictionary: A description of the Alaska geologic mapping schema: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 170, 10 p. https://doi.org/10.14509/30669. The distribution package includes ESRI fonts and style files, along with usage instructions. Further documentation of the symbology is provided by Ekberg, P.G., Hendricks, M.D., and Athey, J.E., 2021, AK GeMS symbology: A description of the AK GeMS style file: Alaska Division of Geological & Geophysical Surveys Miscellaneous Publication 169, 7 p. https://doi.org/10.14509/3058420172018ground conditioncompleteNone planned-141.653213-141.00000064.00147863.612549ISO 19115 Topic CategorygeoscientificInformationAlaska Division of Geological & Geophysical SurveysAerialAerial PhotographyAlluvialAlluvial DepositsAmphiboliteAmphibolite Facies UnitsBedrock GeologyColluvial DepositsComplex DepositsGeMSGeologicGeologic MapGeologic Mapping StandardsGisGlacial DepositsIgneousIgneous RocksMetamorphicMetamorphic RocksMetasedimentary RocksOrthogneissQuartziteRemote SensingSchistSedimentarySedimentary RocksSurficialSurficial GeologyAlaska Division of Geological & Geophysical SurveysBedrock CreekBig Timber CreekCherry CreekCrow CreekDewey CreekDivide MountainDude CreekFishhook BendFortymile Mining DistrictGold Bar CreekLiberty CreekMcCord CreekMcElfish CreekMcKinley CreekPrindle VolcanoSixtymile RiverTom Paine CreekAlaska Division of Geological & Geophysical SurveysKlondike AssemblageLake George AssemblageNasina AssemblageWalker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of AmericaCretaceousDevonianLate CretaceousLate TriassicMississippianPaleozoicPermianQuaternaryTriassicThis report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.Alaska Division of Geological & Geophysical SurveysMetadata Managermailing and physical

3354 College Road

FairbanksAK99709-3707USA(907)451-5020(907)451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysPlease view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.We would like to thank James V. Jones III (USGS, Anchorage) and Robert Gillis (DGGS) for thorough and constructive reviews of the geologic map, map unit descriptions, and report. The DGGS Northeast Tanacross project was funded by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G18AC00137 for 2018 and by State of Alaska general funds. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.Wypych, Alicja2021Northeast Tanacross geologic mapping project, AlaskaReport of InvestigationRI 2020-9Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys75 phttps://doi.org/10.14509/30537This data release provides legacy geospatial data converted to the GeMS and AK GeMS specifications. Attribute fields within each feature class are populated using corresponding applicable values from the GeMS and AK GeMS specifications. When known, certainty in attribute interpretation is indicated in the relevant fields. Attribute accuracy varies throughout the map and is scale-dependent.All polygon features were topologically validated according to specifications of the AK GeMS geologic mapping schema.This publication is part of a DGGS Report of Investigations (RI). An RI is the completed product of original research and analysis, and RIs use professional cartography and undergo rigorous peer review, editing, and revision.This data release provides legacy geospatial data converted to the GeMS and AK GeMS specifications. To record the originating authors' degree of confidence in the location of features, the data include descriptive fields within each feature class and accompanying orientation and location confidence lookup tables. Certainty in feature boundaries or location varies throughout the map.Aleinikoff, J.N.Dusel-Bacon, CynthiaFoster, H.L.1986Geochronology of augen gneiss and related rocks, Yukon-Tanana terrane, east-central AlaskaBulletinv. 97, no. 5UnknownGeological Society of Americahttp://gsabulletin.gsapubs.org/content/97/5/626.abstractpaper1986publication dateAleinikoff, J.N. and others, 1986Geologic map compilationBurns, L.E.Fugro Airborne Surveys Corp.Fugro GeoServices, Inc.2011Ladue survey area: Magnetic and electromagnetic line, grid, and vector data and Maps, Fortymile mining district, Tanacross Quadrangle, eastern AlaskaGeophysical ReportGPR 2011-1Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys26 sheets, scale 1:63,360, 1 DVDhttps://doi.org/10.14509/2256263360paper2011publication dateBurns, L.E. and others, 2011Geologic map compilationBurns, L.E.Geoterrex-DighemStevens Exploration Management Corp.Emond, A.M.Graham, G.R.C.2015Fortymile mining district electromagnetic and magnetic airborne geophysical survey data compilationGeophysical ReportGPR 2015-4Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys12 phttps://doi.org/10.14509/29411paper2015publication dateBurns, L.E. and others, 2015Geologic map compilationDusel-Bacon, CynthiaHopkins, M.J.Mortensen, J.K.Dashevsky, S.S.Bressler, J.R.Day, W.C.2006Paleozoic tectonic and metallogenic evolution of the pericratonic rocks of east-central Alaska and adjacent YukonSpecial Paper45UnknownGeological Association of Canadanullpaper2006publication dateDusel-Bacon, Cynthia and others, 2006, p. 25-74Geologic map compilationDusel-Bacon, CynthiaAleinikoff, J.N.1996U-Pb zircon and titanite ages for augen gneiss from the Divide Mountain area, eastern Yukon-Tanana Upland, Alaska, and evidence for the composite nature of the Fiftymile BatholithBulletinB 2152United StatesU.S. Geological Surveyp. 131-141https://dggs.alaska.gov/pubs/id/4323paper1996publication dateDusel-Bacon, Cynthia and Aleinikoff, J.N., 1996, p. 131-141Geologic map compilationEkberg, P.G.Hendricks, M.D.Athey, J.E.2021AK GeMS symbology: A description of the AK GeMS style fileMiscellaneous PublicationMP 169Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys7 phttps://doi.org/10.14509/30584paper2021publication dateEkberg, P.G. and others, 2021GIS analysis and digital cartographyEmond, A.M.CGGBurns, L.E.Graham, G.R.C.CGG Land (US) Inc.2015Tok electromagnetic and magnetic airborne geophysical survey data compilationGeophysical ReportGPR 2015-2Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys13 phttps://doi.org/10.14509/29347paper2015publication dateEmond, A.M. and others, 2015Geologic map compilationFlynn, R.L.2003Geology of the Boundary area, Eagle A-1 and Tanacross D-1 quadrangles, east-central AlaskaFairbanks, AlaskaUniversity of Alaska Fairbanksnullpaper2003publication dateFlynn, R.L., 2003Geologic map compilationGill, R.D.1977Geology and mineral deposits of the southwest quarter of the Tanacross D-1 Quadrangle, AlaskaBellingham, WashingtonWestern Washington Universitynullpaper1977publication dateGill, R.D., 1977Geologic map compilationHendricks, M.D.Ekberg, P.G.Athey, J.E.Wyatt, W.C.Willingham, A.L.Naibert, T.J.2021AK GeMS data dictionary: A description of the Alaska geologic mapping schemaMiscellaneous PublicationMP 170Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 phttps://doi.org/10.14509/30669paper2021publication dateHendricks, M.D. and others, 2021GIS analysis and digital cartographyNaibert, T.J.Benowitz, J.A.Wypych, AlicjaSicard, K.R.Twelker, Evan201840Ar/39Ar data from the Tanacross D-1 and D-2, Big Delta B-4 and B-5, and Mount Hayes A-6 quadrangles, AlaskaRaw Data FileRDF 2018-3Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys15 phttps://doi.org/10.14509/30112paper2018publication dateNaibert, T.J. and others, 2018Geologic map compilationSzumigala, D.J.Newberry, R.J.Werdon, M.B.Athey, J.E.Flynn, R.L.Clautice, K.H.2002Bedrock geologic map of the Eagle A-1 Quadrangle, Fortymile mining districtPreliminary Interpretive ReportPIR 2002-1BFairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys1 sheet, scale 1:63,360https://doi.org/10.14509/286463360paper2002publication dateSzumigala, D.J. and others, 2002Geologic map compilationTodd, ErinWypych, AlicjaKylander-Clark, Andrew2019U-Pb and Lu-Hf isotope, age, and trace element data from zircon separates from the Tanacross D-1, and parts of D-2, C-1, and C-2 quadranglesRaw Data FileRDF 2019-5Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 phttps://doi.org/10.14509/30198paper2019publication dateTodd, Erin and others, 2019Geologic map compilationWerdon, M.B.Newberry, R.J.Szumigala, D.J.2001Bedrock geologic map of the Eagle A-2 Quadrangle, Fortymile mining district, AlaskaPreliminary Interpretive ReportPIR 2001-3BFairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys1 sheet, scale 1:63,360https://doi.org/10.14509/267063360paper2001publication dateWerdon, M.B. and others, 2001Geologic map compilationWypych, AlicjaHubbard, T.D.Naibert, T.J.Athey, J.E.Newberry, R.J.Sicard, K.R.Twelker, EvanWerdon, M.B.Willingham, A.L.Wyatt, W.C.Lockett, A.C.2019Northeastern Tanacross geologic map, Tanacross D-1, D-2, C-1, and C-2 quadrangles, AlaskaPreliminary Interpretive ReportPIR 2019-6Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys20 p., 1 sheet, scale 1:63,360https://doi.org/10.14509/3019763360paper2019publication dateWypych, Alicja and others, 2019Geologic map compilationU.S. Geological Survey National Cooperative Geologic Mapping Program2020GeMS (Geologic Map Schema) - A standard format for the digital publication of geologic mapsTechniques and MethodsTM 11-B10United StatesU.S. Geological Survey1 phttps://dggs.alaska.gov/pubs/id/30585paper2020publication dateU.S. Geological Survey National Cooperative Geologic Mapping Program, 2020GIS analysis and digital cartographyQuaternary unconsolidated deposits - This map includes unconsolidated surficial deposits in the Tanacross D-1 Quadrangle, the eastern one-third of the Tanacross D-2 Quadrangle, the northern half of the Tanacross B-2 Quadrangle, and the northeastern one-third of the Tanacross B-2 Quadrangle. To create this map we incorporated (1) geologic information from previous geologic mapping and published literature, (2) new interpretations using remotely sensed imagery, and (3) information gathered from limited field investigations. Previous geologic mapping of the unconsolidated deposits in the Tanacross Quadrangle includes work by Foster (1970) at a scale of 1:250,000, which provided a framework for our mapping and was instrumental in understanding the regional distribution and character of Quaternary deposits. Weber (1986) described the glacial history of the Yukon Tanana Upland and gave detailed descriptions of the extent and character of these deposits. Her work, along with glacial limits mapped by PÃ©wÃ© and others (1967) helped us identify and map glacial deposits in the map area. Work by Pinney (2001) and Stevens and Burns (2010) in the Eagle A-1 and A-2 quadrangles enabled us to understand the distribution and character of deposits in adjoining areas to the north and enhanced our understanding of the morphology and distribution of alluvial terraces, many of which are gold-bearing and extend southward into this map area. Mapping at a scale of 1:50,000 in the adjoining Borden Creek and Crag Mountain quadrangles by Jackson (2005a, 2005b) allowed comparisons with the distribution and character of deposits in Canada. A complete reference list is available in the accompanying report.2018Remotely sensed imagery - Surficial geology was mapped by interpreting 2.5-m-resolution SPOT 5 color-infrared and natural color red-green-blue (RGB) imagery (Â©2013, Distribution SpotImage S.A., SICORP, USA, all rights reserved) collected in 2009 and 2010 and stereoscopic pairs of approximately 1:65,000-scale, false-color, infrared aerial photographs taken in 1978 and 1981. SPOT 5 imagery was interpreted in ArcGIS Pro by overlaying it on hillshade and slopeshade images derived from Interferometric Synthetic Aperture Radar (IFSAR) bare-earth digital-elevation models (DEMs) created using data collected in 2010. By using the pseudo-3-D functionality of ArcGIS Pro and adjusting the transparency of the SPOT 5 imagery and the transparency and color of hillshade and slopeshade images, we were able to visualize subtle differences in features and identify geologic landforms. We used aerial photographs to identify geologic features and check our interpretations. Geospatial polygon features that represent geologic units were drawn using onscreen digitizing techniques in ArcGIS Pro.2018Geologic mapping - Fieldwork for bedrock investigations, including ridge traverses and examination of riverbank exposures, took place during two periods: a reconnaissance mapping effort June 12-22, 2017, and a detailed campaign June 18-July 16, 2018. Field notes, magnetic measurements, and rock samples were compiled and collected throughout the map area. Mappers recorded observations on 1:50,000- and 1:63,360-scale topographic base maps and compiled using ArcGIS software. Location data were collected using GPS-enabled tablets (2017 Samsung Galaxy Tab A) running the ESRI Collector App.2018Laboratory data compilation - Selected samples were submitted for geochemical and geochronologic analysis. The results were used to further interpret rock units and the stratigraphic and structural history of the map area.2018Geologic map compilation - The conceptual framework for the regional geology relies heavily on preexisting literature. The map area is heavily vegitated; consequently, the map interpretation relies heavily on geochemical and geochronological findings, magnetic and electromagnetic survey data, and observations from rocks collected from pits dug into rocky colluvial deposits below surficial loess or sand. A comprehensive bibliographic reference list of prior work used to identify and delineate rock units and structural elements is provided in the accompanying report. The map and report received technical review and editing by several scientists familiar with the subject matter. The authors incorporated the reviewers' suggestions into the final draft when deemed appropriate.Aleinikoff, J.N. and others, 1986Burns, L.E. and others, 2011Burns, L.E. and others, 2015Dusel-Bacon, Cynthia and others, 2006, p. 25-74Dusel-Bacon, Cynthia and Aleinikoff, J.N., 1996, p. 131-141Emond, A.M. and others, 2015Flynn, R.L., 2003Gill, R.D., 1977Naibert, T.J. and others, 2018Szumigala, D.J. and others, 2002Todd, Erin and others, 2019Werdon, M.B. and others, 2001Wypych, Alicja and others, 20192020GIS analysis and digital cartography - This data distribution package's geologic and geographic features were organized and attributed according to the AK GeMS geologic mapping schema. The data were then programmatically transformed to provide download options in three formats: (1) an AK GeMS data package that includes the complete AK GeMS database and associated files, (2) a GeMS data package that is a conversion of the AK GeMS database into the base GeMS standard published by the USGS, and (3) a shapefile data package that includes two simple shapefile representations of the data.Ekberg, P.G. and others, 2021Hendricks, M.D. and others, 2021U.S. Geological Survey National Cooperative Geologic Mapping Program, 20202021vectorUniversal Transverse Mercator70.999600-1410500000.0000000coordinate pair.00000001.00000001MetersNAD83GRS 806378137298.257222101000025ne_tanacross_ak_gems_db_pkgGeodatabase, layer files, style files, and fontsAlaska Division of Geological & Geophysical Surveysne_tanacross_ak_gems_db_pkgne_tanacross_gems_db_pkgGeodatabase, layer files, style files, and fontsAlaska Division of Geological & Geophysical Surveysne_tanacross_gems_db_pkgne_tanacross_gems_shapefile_pkgShapefiles and open data filesAlaska Division of Geological & Geophysical Surveysne_tanacross_gems_shapefile_pkgAlaska Division of Geological & Geophysical SurveysMetadata Managermailing and physical

3354 College Road

FairbanksAK99709-3707USA(907)451-5020(907)451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysFGDC Content Standard for Digital Geospatial MetadataFGDC-STD-001-1998If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys.https://dggs.alaska.gov/metadata/dggs.extdggs metadata extensions