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1. FIELD STATION LOCATIONS AND MAGNETIC SUSCEPTIBILITY DATA FOR THE CHENA--POGO AND MOUNT HARPER PROJECTS, BIG DELTA AND CIRCLE QUADRANGLES, ALASKA, COLLECTED JUNE-SEPTEMBER 2023.

Author

Gavel, Michelle M., Twelker, Evan, Wypych, Alicja, Naibert, Travis J., Newberry, Rainer J., Szumigala, David J., Wildland, Alec D., Barrera, Michael L., Biegel, Jenna N., Harvey, David A., Ketcham, Richard A., Muller, Isabella P., and Reagan, Sean P.

Subjects
*MAGNETIC susceptibility, *GEOPHYSICAL surveys, *GEOLOGICAL mapping, *GEOLOGICAL maps, *LOCATION data
Published
2023
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2. GEOCHEMICAL DATA FROM SAMPLES COLLECTED IN 2022 FOR THE MOUNT HARPER GEOLOGIC MAPPING PROJECT, BIG DELTA, MOUNT HAYES, AND EAGLE QUADRANGLES, ALASKA.

Author

Wypych, Alicja, Twelker, Evan, Naibert, Travis J., Gavel, Michelle M., Newberry, Rainer J., Szumigala, David J., Wildland, Alec D., Barrera, Michael L., Harvey, David A., Muller, Izabella P., Fessenden, Serena N., and Blackwell, Noel J.

Subjects
*GEOLOGICAL mapping, *GEOLOGICAL maps, *INDUCTIVELY coupled plasma atomic emission spectrometry
Published
2023

3. FIELD STATION LOCATIONS AND MAGNETIC SUSCEPTIBILITY DATA COLLECTED IN 2022 FOR THE MOUNT HARPER PROJECT, EAGLE, BIG DELTA, AND MOUNT HAYES QUADRANGLES, ALASKA.

Author

Gavel, Michelle M., Twelker, Evan, Wypych, Alicja, Naibert, Travis J., Newberry, Rainer J., Szumigala, David J., Wildland, Alec D., Barrera, Michael L., Blackwell, Noel J., Fessenden, Serena N., Harvey, David A., and Muller, Isabella P.

Subjects
*MAGNETIC susceptibility, *GEOLOGICAL maps, *GEOLOGICAL mapping, *ACQUISITION of data
Published
2023
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12. MINERAL OCCURRENCES IN THE TOK RIVER AREA, EASTERN ALASKA RANGE.

Author

Twelker, Evan, Newberry, Rainer J., Wypych, Alicja, Sicard, Karri R., and Naibert, Travis J.

Subjects
*SULFIDE minerals, *PYRRHOTITE, *METAMORPHIC rocks, *MINERALS, *GOLD ores, *SKARN, *MOLYBDENITE
Abstract

The Tok River area (Tanacross A-5 and A-6 quadrangles) of the eastern Alaska Range hosts a variety of ages and styles of mineralization, including stratabound basemetal sulfide, intrusion-related gold-copper-silver, and structurally controlled gold. Stratabound base-metal (Zn-Pb-Cu-Ag-Au) sulfide prospects occur in the Tanacross A-6 Quadrangle, where they are known in part as the Eagle trend. Mineralization is hosted by thin marble beds within a metamorphic package dominated by siliciclastic and rare volcanic protoliths. Sulfide minerals include sphalerite, galena, chalcopyrite, pyrrhotite, and pyrite; associated minerals include calcite, ankerite, siderite, albite, phengite, chlorite, ferro-actinolite, stilpnomelane, Fe-clinopyroxene, Ca-Mn garnet, ilvaite, and barite. Mineral assemblages, compositions, and textures indicate that base-metal sulfide mineralization experienced Permian through Jurassic regional metamorphism, and Pb-isotopic ratios are closely similar to those of Devonian to Mississippian syngenetic deposits of Interior Alaska. We interpret the Eagle trend to be a continuation of the PP-LZ trend of the Delta mineral belt, and that the Tok River area prospects are most similar to sedimentary-exhalative (SEDEX)-type systems. The Hona prospect comprises Au-Cu-Ag mineralization developed in association with a multiphase hypabyssal granodiorite stock of Late Cretaceous (ca. 75 Ma) age. Mineralization occurs with disseminated pyrrhotite, chalcopyrite, trace molybdenite, and secondary biotite within the intrusion, and with disseminated and veinlet-hosted pyrite and chalcopyrite in adjacent metamorphic rocks. Silicification, sodic, and argillic alteration occur locally, but well-developed sericitic alteration is lacking. The prospect is similar in age to the nearby Peak gold skarn and is associated with intrusions of similar composition. The geochemical signature of Hona mineralization (Au-Cu-Ag-As-Bi-Te) is similar to that of the Peak skarn and distinct from the coeval Taurus Cu-Mo-Au porphyry system. Structurally controlled gold prospects of the White Gold trend appear to have formed well after mid-Cretaceous metamorphic cooling. Mafic and felsic dikes of likely Paleogene age occur locally with structurally controlled gold mineralization and are both pre-/syn- and post-mineralization in timing. Advanced argillic alteration affects Au-As-mineralized dikes as well as mineralized country rock; such alteration reflects highly acidic hydrothermal fluids and is inconsistent with an orogenic gold deposit model. If the White Gold prospects were emplaced during the Paleocene, they are similar in age and style to the Hajdukovich property near Delta Junction and may be genetically linked to ca. 55 Ma extensional tectonics and magmatism. [ABSTRACT FROM AUTHOR]

Published
2020

16. DGGS Earth MRI geologic mapping and geophysics program update.

Author

Twelker, Evan, Emond, Abraham, Newberry, Rainer, Naibert, Travis, Gavel, Michelle, Buchanan, Wes, Szumigala, David, and Barrera, Michael

Subjects
*GEOLOGICAL mapping, *GEOLOGICAL maps, *MAGNETIC resonance imaging, *GEOPHYSICAL surveys, *MINES & mineral resources, *CARTOGRAPHY software
Published
2023

17. U-PB ZIRCON AGE DATA FROM META-IGNEOUS ROCKS IN THE CLEARWATER MOUNTAINS, MOUNT HAYES A-6 QUADRANGLE, ALASKA.

Author

Twelker, Evan and O'Sullivan, Paul

Subjects
*ZIRCON, *GEOLOGICAL time scales, *IGNEOUS rocks, *CRYSTALLIZATION, *SEDIMENTARY rocks
Abstract

We report U-Pb zircon geochronology results for one metavolcanic and one metaplutonic rock sample from the Mount Hayes A-6 Quadrangle of central Alaska. These samples are representative of rock units assigned to the Clearwater terrane of Jones and others (1987), a sequence of greenschist-grade metavolcanic and metasedimentary rocks of poorly constrained age and tectonic origin. Our results indicate a crystallization age of 277.33 ± 11.84 Ma for a felsic metavolcanic rock, and a 268.05 ± 11.64 Ma crystallization age for a granitic metaplutonic unit intruding the former. [ABSTRACT FROM AUTHOR]

Published
2016

18. PRELIMINARY REPORT ON MINERAL OCCURRENCES IN THE TOK RIVER AREA, ALASKA.

Author

Twelker, Evan, Freeman, Larry K., Sicard, Karri R., and Busk, Alexandra C.

Subjects
*GEOPHYSICAL surveys, *RIVERS, *MINERAL processing, *MINES & mineral resources
Abstract

The article presents results of a preliminary report conducted by the State of Alaska, Department of Natural Resources, which explores the geological and geophysical survey on mineral occurrences at the Tok River Area in Alaska. A brief overview on the geophysical structure of the area is mentioned. It also notes on the Kennecott Exploration on surface exploration and drilling in 1997 and 1998.

Published
2016

19. MAJOR-OXIDE AND TRACE-ELEMENT GEOCHEMICAL DATA FROM ROCKS COLLECTED IN 2015 IN THE WRANGELLIA MINERAL ASSESSMENT AREA, ALASKA.

Author

Wypych, Alicja, Twelker, Evan, Freeman, Larry K., Lande, Lauren, Newberry, Rainer J., Reioux, David A., and Sicard, Karri R.

Subjects
*ROCKS, *PALLADIUM, *INDUCTIVELY coupled plasma mass spectrometry, *RARE earth metals
Abstract

The article offers information on a report by the Department of Natural Resources of Alaska on data of trace elements found in rocks of Wrangellia mineral assessment area in Alaska. Topics discussed include determination of rare-earth element in rock samples by inductively-coupled plasma-mass spectroscopy, analysis of palladium by inductively coupled plasma mass spectrometry (ICP-MS), and analysis of minor oxides by lithium metaborate fusion digestion.

Published
2015

20. EXPLANATION OF MAP UNITS: Geologic map of the Talkeetna Mountains C-4 Quadrangle and adjoining areas, central Alaska (1:50,000 scale).

Author

Twelker, Evan, Hubbard, Trent D., Wypych, Alicja, Sicard, Karri R., Newberry, Rainer J., Reioux, David A., Freeman, Lawrence K., and Lande, Lauren L.

Subjects
*MAPS -- Symbols, *ALLUVIUM, *RHYOLITE, *SANDSTONE, *SILICA
Abstract

The article offers information on the symbols used in map units. Topics discussed include use of Qa to describe undifferentiated floodplain alluvial deposits, use of Trrp to show high silica rhyolite, use of Kg indicates granite rocks and, use of KJmf to show metamorphosed and interbedded sandstone in the area.

Published
2015

21. MAJOR-OXIDE AND TRACE-ELEMENT GEOCHEMICAL DATA FROM ROCKS COLLECTED IN 2014 IN THE WRANGELLIA MINERAL ASSESSMENT AREA, TALKEETNA MOUNTAINS C-4, C-3, AND B-4 QUADRANGLES, ALASKA.

Author

Wypych, Alicja, Twelker, Evan, Freeman, Larry K., Lande, Lauren, Newberry, Rainer J., Reioux, David A., and Sicard, Karri R.

Subjects
*RARE earth metals, *MAGMAS, *METHODOLOGY, *TRACE elements, *MINERALIZATION
Abstract

The article discusses the exploration for rare-earth elements by the Alaska Division of Geological & Geophysical Surveys at the Talkeetna Mountains C-4, C-3, and B-4 quadrangles off the western Wrangellia terrane. Sample collection and geopositioning for prospective Late Triassic magmatic Ni-Cu-Co-PGE deposits is described. Also included is the analytical methodology for specimen prepared with the PREP-31 package by ALS Minerals group under ISO/IEC 17025-2005 guidelines for trace element test.

Published
2014

22. MAJOR-OXIDE, MINOR-OXIDE, AND TRACE-ELEMENT GEOCHEMICAL DATA FROM ROCKS AND STREAM SEDIMENTS IN THE WRANGELLIA MINERAL ASSESSMENT AREA, GULKANA, HEALY, MOUNT HAYES, AND TALKEETNA MOUNTAINS QUADRANGLES, ALASKA.

Author

Twelker, Evan, Bachmann, Erik N., Freeman, Larry K., Newberry, Rainer J., Reioux, David A., Sicard, Karri R., Tuzzolino, Amy L., Wright, Thomas C., and Wypych, Alicja

Subjects
*GEOCHEMICAL prospecting, *MAFIC rocks, *GEOLOGICAL surveys, *PROSPECTING
Abstract

The article discusses the geochemical exploration of mafic intrusions in the Wrangellia terrane and the Talkeetna and Mount Hayes Quadrangles in Alaska. Collection and preparation protocols followed by the Division of Geological & Geophysical Surveys (DGGS) are indicated. Analytical procedures for each type of sample is presented.

Published
2014

23. FIELD STATION LOCATIONS AND MAGNETIC SUSCEPTIBILITY DATA COLLECTED IN 2019 FOR THE EASTERN TANACROSS PROJECT, TANACROSS AND NABESNA QUADRANGLES, ALASKA.

Author

Naibert, Travis J., Twelker, Evan, Wypych, Alicja, Athey, Jennifer E., Newberry, Rainer J., Lopez, Julian A., Regan, Sean P., Sicard, Karri R., Wildland, Alec D., and Wyatt, W. Chris

Subjects
*MAGNETIC susceptibility, *GEOLOGICAL surveys, *GEOLOGICAL mapping, *GEOPHYSICAL surveys, *MINES & mineral resources, *HYDROGEN as fuel
Published
2020

24. Cretaceous to Tertiary magmatism and associated mineralization in the Lime Hills C-1 Quadrangle, Western Alaska Range.

Author

Sicard, Karri R., Twelker, Evan, Freeman, Larry K., Wypych, Alicja, Benowitz, Jeff A., and Kass, M. Andy

Subjects
*MINERALIZATION, *GEOLOGICAL maps
Abstract

Several maps which show cretaceous to tertiary magmatism and associated mineralization in the Lime Hills C-1 quadrangle of the Western Alaska range by the Alaska Miners Association Annual Convention on November 5, 2014 are presented.

Published
2014

25. NEW GEOCHEMICAL AND GEOPHYSICAL DATA FROM THE WESTERN WRANGELLIA MINERALS ASSESSMENT AREA.

Author

Twelker, Evan and Burns, Laurel

Subjects
*MINERALS, *GEOCHEMICAL prospecting, *GEOPHYSICAL surveys, *GEOLOGICAL surveys, *GEOCHEMISTRY
Abstract

The article presents the result of the geochemical and geophysical assessment conducted on the western Wrangellia minerals area by the Alaska Division of Geological & Geophysical Surveys. Findings highlighted include the project objectives, the components of the geological/geochemical program and the two challenges in the project. Also presented are the scenarios in the Ni-Cu-PGE deposit-forming processes.

Published
2014

26. Updates on DGGS Geologic Mapping Efforts in Eastern Interior Alaska.

Author

Naibert, Travis J., Wypych, Alicja, Twelker, Evan, Gavel, Michelle M., Wildland, Alec D., Newberry, Rainer J., Szumigala, David J., Barrera, Michael L., and Fessenden, Serena N.

Subjects
*GEOLOGICAL maps, *GEOLOGICAL mapping, *GOLD ores, *MUSCOVITE, *GEOLOGICAL surveys, *SHEAR zones
Published
2022

30. GEOCHEMISTRY AND ORIGIN OF METAMORPHOSED MAFIC ROCKS FROM THE LOWER PALEOZOIC MORETOWN AND CRAM HILL FORMATIONS OF NORTH-CENTRAL VERMONT: DELAMINATION MAGMATISM IN THE WESTERN NEW ENGLAND APPALACHIANS.

Author

COISH, RAYMOND, KIM, JONATHAN, TWELKER, EVAN, ZOLKOS, SCOTT, and WALSH, GREGORY

Subjects
*MAFIC rocks, *METAMORPHISM (Geology), *IGNEOUS rock analysis, *ANALYTICAL geochemistry, *GEOLOGICAL formations
Abstract

The Moretown Formation, exposed as a north-trending unit that extends from northern Vermont to Connecticut, is located along a critical Appalachian litho-tectonic zone between the paleomargin of Laurentia and accreted oceanic terranes. Remnants of magmatic activity, in part preserved as metamorphosed mafic rocks in the Moretown Formation and the overlying Cram Hill Formation, are a key to further understanding the tectonic history of the northern Appalachians. Field relationships suggest that the metamorphosed mafic rocks might have formed during and after Taconian deformation, which occurred at ca. 470 to 460 Ma. Geochemistry indicates that the sampled metamorphosed mafic rocks were mostly basalts or basaltic andesites. The rocks have moderate TiO2 contents (1-2.5 wt %), are slightly enriched in the light-rare earth elements relative to the heavy rare earths, and have negative Nb-Ta anomalies in MORB-normalized extended rare earth element diagrams. Their chemistry is similar to compositions of basalts from western Pacific extensional basins near volcanic arcs. The metamorphosed mafic rocks o f this study are similar in chemistry to both the pre-Silurian Mount Norris Intrusive Suite o f northern Vermont, and also to some o f Late Silurian rocks within the Lake Memphremagog Intrusive Suite, particularly the Comerford Intrusive Complex of Vermont and New Hampshire. Both suites may be represented among the samples of this study. The geochemistry of all samples indicates that parental magmas were generated in supra-subduction extensional environments during lithospheric delamination. [ABSTRACT FROM AUTHOR]

Published
2015
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31. Alaska's Mineral Industry 2015.

Author

Athey, Jennifer E., Werdon, Melanie B., Twelker, Evan, and Henning, Mitch W.

Subjects
*MINERAL industries, *GOVERNMENT revenue, RED Dog Mine (Alaska)
Abstract

An industry report of the mineral industry in Alaska is presented from publisher Alaska Division of Geological & Geophysical Surveys (DGGS), with topics including government revenue from the state's mineral industry, primary metals production from 1880-2015, and the Red Dog Mine.

Published
2015

32. New Data and Insight on the Late Triassic Wrangellia Magmatic Ni-Cu-Co-PGE System in the Talkeetna Mountains, Central Alaska.

Author

Twelker, Evan, Wypych, Alicja, and Newberry, Rainer J.

Subjects
*MINERALIZATION, *METALLOGENIC provinces, *IGNEOUS intrusions, *MAGMAS, *PLATINUM group, *GEOPHYSICAL surveys
Abstract

Ni-Cu-Co-PGE mineralization occurs as magmatic sulfides in Late Triassic mafic-ultramafic intrusions of the Wrangellia terrane in Alaska and the Yukon. Parts of this metallogenic system have seen detailed study and exploration, notably at the Quill Creek Complex and Wellgreen deposit in the Yukon Territory, and at several prospects in the Eastern Alaska Range, including the Alpha Complex. Recent mapping in the Talkeetna Mountains showed that these mafic-ultramafic intrusions and their extrusive equivalent, the Nikolai Greenstone Large Igneous Province (LIP), continue at least 60 km to the southwest of the previously recognized extent. This opens up geologic potential for magmatic Ni-Cu-Co-PGE deposits to occur in the Talkeetna Mountains of central Alaska. As part of its ongoing Airborne Geophysical/Geological Mineral Inventory and Strategic and Critical Minerals Assessment programs, the Alaska Division of Geological and Geophysical Surveys (DGGS) initiated a multi-year project to improve the understanding of mineral potential in western Wrangellia. The project began in 2013 with acquisition of magnetic and electromagnetic (EM) geophysical data over unsurveyed portions of the terrane in the Clearwater and Talkeetna Mountains. DGGS geologists completed a three week field program of geologic mapping, rock, and stream sediment sampling in 2013, and followed up with 1:50,000-scale mapping of the Talkeetna Mountains C-4 Quadrangle during the 2014 field season. Gabbroic and ultramafic rocks of probable Late Triassic age were sampled across the project area. Previous work divides the Nikolai Greenstone into a stratigraphically lower, depleted mantle-derived, low TiO2 group and an upper, enriched mantle-derived, high TiO2 group. Both intrusive and extrusive members of this earlier petrogenetic suite occur throughout western Wrangellia. DGGS investigations indicate that PGE enrichment is associated only with the earlier, low TiO2 suite. Outside of the Mount Hayes Quadrangle, the most prominent low-TiO2 type mafic-ultramafic complex is the 16 km long, up to 700m-thick sill-form body in the northeastern Talkeetna Mountains south of Butte Creek. Mapping and analytical work indicate that this is a multiphase intrusive complex dominated by gabbro to olivine gabbro, with texture varying from fine-grained to pegmatitic. The thickest, most mafic section shows large-scale gradational variation in mineralogy from olivine-rich troctolite at the center to olivine gabbro above and below, apparent differentiation which is similar to that seen at the Quill Creek Complex. Microprobe results show that olivine grains near the base of this intrusive complex have Ni concentrations around 2900 ppm, whereas olivine in the center of the complex average 1100 ppm Ni. This apparent Ni depletion is comparable to that observed at Wellgreen. Sulfide grains, including intergrown pyrrhotite and pentlandite, were found to occur at grain interstices and as rare inclusions in Ni-depleted olivine. Analyses from the northeastern half of the study area yield values of PGE per 100 percent sulfide that are on par with values for the Wellgreen deposit. These data, along with the olivine Ni depletion, imply an early separation of a sulfide melt and a high degree of sulfide-silicate melt interaction, indicating that this part of Wrangellia has completed important prerequisites for the formation of Ni-Cu-Co-PGE deposits. [ABSTRACT FROM AUTHOR]

Published
2014

34. Alaska's Mineral Industry 2015.

Author

Athey, Jennifer E., Werdon, Melanie B., Twelker, Evan, and Henning, Mitch W.

Subjects
*MINERAL industries, *EMPLOYMENT, *MINERALS
Abstract

An industry report for the mineral industry in Alaska for 2015 is presented from the Alaska Department of Natural Resources, Division of Geological & Geophysics Surveys, with topics including employment, minerals-related government activities, and development and production.

Published
2015

35. 40AR/39AR DATA FROM ROCKS COLLECTED IN 2013 IN THE WRANGELLIA MINERAL ASSESSMENT AREA, GULKANA, HEALY, MOUNT HAYES, AND TALKEETNA MOUNTAINS QUADRANGLES, ALASKA.

Author

Benowitz, Jeff A., Layer, Paul W., and Twelker, Evan

Subjects
*GEOCHRONOMETRY, *CRYSTALLINE rocks, *METAMORPHIC rocks, *JURASSIC Period, *CRETACEOUS Period
Abstract

This DGGS Raw Data File presents 40Ar/39Ar age dating results from selected mafic to intermediate intrusions encountered during a geological and geochemical resource assessment project in the Gulkana, Healy, Mount Hayes, and Talkeetna Mountains quadrangles. Three intrusions returned mid-Cretaceous crystallization ages, while one olivine gabbro returned a Late Triassic crystallization age. Two altered or metamorphosed samples yielded Late Jurassic and Early Cretaceous ages. Analyses were performed by the University of Alaska Fairbanks Geochronology Laboratory, and results were reported by Paul Layer and Jeff Benowitz. Products included in this data release are: a summary of sample collection methods, the laboratory report, analytical data tables and associated metadata, and plots of the 40Ar/39Ar age spectra, Ca/K and Cl/K ratios. All components of this data release are available on the DGGS website. [ABSTRACT FROM AUTHOR]

Published
2014
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36. MAJOR-OXIDE, MINOR-OXIDE, AND TRACE-ELEMENT GEOCHEMICAL DATA FROM ROCKS IN THE STYX RIVER AREA, LIME HILLS C-1 QUADRANGLE, LIME HILLS, MCGRATH, TALKEETNA, AND TYONEK QUADRANGLES, ALASKA.

Author

Sicard, Karri R., Wypych, Alicja, Twelker, Evan, Bachmann, Erik N., Freeman, Larry K., Newberry, Rainer J., Reioux, David A., Tuzzolino, Amy L., and Wright, Thomas C.

Subjects
*GEOLOGICAL surveys, *RARE earth metals, *PRECIOUS metals, *IGNEOUS intrusions
Abstract

The article discusses a survey for rare-earth elements and precious minerals conducted by the Alaska Division of Geological & Geophysical Surveys (DGGS) along Styx River in the Lime Hills C-1 Quadrangle. Plutonic complexes in the area are noted. Collection, preparation and analysis of rock samples are described.

Published
2014

37. Oligocene-Neogene lithospheric-scale reactivation of Mesozoic terrane accretionary structures in the Alaska Range suture zone, southern Alaska, USA.

Author

Waldien, Trevor S., Roeske, Sarah M., Benowitz, Jeffrey A., Twelker, Evan, and Miller, Meghan S.

Subjects
*SUTURE zones (Structural geology), *MESOZOIC Era, *FAULT zones, *METAMORPHIC rocks, *GEOLOGICAL mapping, *SHEAR zones
Abstract

Terrane accretion forms lithospheric-scale fault systems that commonly experience long and complex slip histories. Unraveling the evolution of these suture zone fault systems yields valuable information regarding the relative importance of various upper crustal structures and their linkage through the lithosphere. We present new bedrock geologic mapping and geochronology data documenting the geologic evolution of reactivated shortening structures and adjacent metamorphic rocks in the Alaska Range suture zone at the inboard margin of the Wrangellia composite terrane in the eastern Alaska Range, Alaska, USA. Detrital zircon uranium-lead (U-Pb) age spectra from metamorphic rocks in our study area reveal two distinct metasedimentary belts. The Maclaren schist occupies the inboard (northern) belt, which was derived from terranes along the western margin of North America during the mid- to Late Cretaceous. In contrast, the Clearwater metasediments occupy the outboard (southern) belt, which was derived from arcs built on the Wrangellia composite terrane during the Late Jurassic to Early Cretaceous. A newly discovered locality of Alaska-type zoned ultramafic bodies within the Clearwater metasediments provides an additional link to the Wrangellia composite terrane. The Maclaren and Clearwater metasedimentary belts are presently juxtaposed by the newly identified Valdez Creek fault, which is an upper crustal reactivation of the Valdez Creek shear zone, the Late Cretaceous plate boundary that initially brought them together. 40Ar/39Ar mica ages reveal independent post-collisional thermal histories of hanging wall and footwall rocks until reactivation localized on the Valdez Creek fault after ca. 32 Ma. Slip on the Valdez Creek fault expanded into a thrust system that progressed southward to the Broxson Gulch fault at the southern margin of the suture zone and eventually into the Wrangellia terrane. Detrital zircon U-Pb age spectra and clast assemblages from fault-bounded Cenozoic gravel deposits indicate that the thrust system was active during the Oligocene and into the Pliocene, likely as a far-field result of ongoing flat-slab subduction and accretion of the Yakutat microplate. The Valdez Creek fault was the primary reactivated structure in the suture zone, likely due to its linkage with the reactivated boundary zone between the Wrangellia composite terrane and North America in the lithospheric mantle. [ABSTRACT FROM AUTHOR]

Published
2021
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38. 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.

Author

Wypych, Alicja, Sicard, Karri R., Twelker, Evan, Freeman, Larry K., Lande, Lauren, and Reioux, David A.

Subjects
*ROCKS, *INDUCTIVELY coupled plasma spectrometry, *PALLADIUM, *INDUCTIVELY coupled plasma mass spectrometry
Abstract

The article offers information on a report by the Department of Natural Resources of Alaska on data of trace elements found in rocks of Tok area in Alaska. Topics discussed include testing of rock samples with inductively-coupled plasma-atomic emission spectrometry, analysis of palladium by inductively coupled plasma mass spectrometry (ICP-MS), and determination of rare earth elements by using lithium metaborate fusion digestion.

Published
2015

39. GEOCHEMICAL DATA FROM SAMPLES COLLECTED IN 2020 AND 2021 FOR THE WESTERN TANACROSS PROJECT, TANACROSS QUADRANGLE, ALASKA.

Author

Wypych, Alicja, Gavel, Michelle M., Naibert, Travis J., Avirett, Dylan F., Barrera, Michael L., Hubbard, Angela K., Newberry, Rainer J., Regan, Sean P., Twelker, Evan, Wildland, Alec D., and Wyatt, W. Chris

Subjects
*GEOLOGICAL surveys, *LOCATION data, *FIRE assay, *MINES & mineral resources, *GEOLOGICAL maps, *TRACE elements
Published
2022
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43. MAJOR-OXIDE AND TRACE-ELEMENT GEOCHEMICAL DATA FROM ROCKS COLLECTED IN 2018 FOR THE NORTHEAST TANACROSS PROJECT, TANACROSS C-1, C-2, D-1, AND D-2 QUADRANGLES.

Author

Wypych, Alicja, Naibert, Travis J., Athey, Jennifer E., Newberry, Rainer J., Sicard, Karri R., Twelker, Evan, Werdon, Melanie B., Willingham, Amanda L., and Wyatt, W. Chris

Subjects
*GEOCHEMISTRY, *GEOPHYSICAL surveys, *FINITE element method, *ORE deposits, *INDUCTIVELY coupled plasma atomic emission spectrometry
Published
2018

45. Oligocene-Neogene lithospheric-scale reactivation of Mesozoic terrane accretionary structures in the Alaska Range suture zone, southern Alaska, USA: Reply.

Author

Waldien, Trevor S., Roeske, Sarah M., Benowitz, Jeffrey A., Twelker, Evan, and Miller, Meghan S.

Abstract

The article informs about bedrock geologic mapping and geochronology data documenting the geologic evolution of reactivated shortening structures and adjacent metamorphic rocks in the Alaska Range suture zone at the inboard margin of Wrangellia composite terrane. Topics include Detrital zircon uranium-lead age spectra from metamorphic rocks in distinct metasedimentary belts; and ultramafic bodies within Clearwater metasediments provides an additional link to the Wrangellia composite terrane.

Published
2022
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46. FIELD STATION LOCATIONS AND MAGNETIC SUSCEPTIBILITY DATA COLLECTED IN 2020-2021 FOR THE WESTERN TANACROSS PROJECT, TANACROSS AND EAGLE QUADRANGLES, ALASKA.

Author

Gavel, Michelle M., Wypych, Alicja, Naibert, Travis J., Avirett, Dylan F., Barrera, Michael L., Hubbard, Angie K., Newberry, Rainer J., Regan, Sean P., Twelker, Evan, Wildland, Alec D., and Wyatt, W. Chris

Subjects
*MAGNETIC susceptibility, *GEOLOGICAL maps, *METALLOGENY, *GEOPHYSICAL surveys, *ACQUISITION of data, *GEOLOGICAL mapping, *HYDROTHERMAL deposits
Published
2022
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47. FIELD STATION LOCATIONS AND MAGNETIC SUSCEPTIBILITY DATA COLLECTED IN 2021 FOR THE TAYLOR MOUNTAINPROJECT, TANACROSS AND EAGLE QUADRANGLES, ALASKA.

Author

Gavel, Michelle M., Wypych, Alicja, Naibert, Travis J., Avirett, Dylan F., Barrera, Michael L., Hubbard, Angie K., Newberry, Rainer J., Regan, Sean P., Twelker, Evan, Wildland, Alec D., and Chris Wyatt, W.

Subjects
*MAGNETIC susceptibility, *GEOLOGICAL maps, *METALLOGENY, *GEOPHYSICAL surveys, *ACQUISITION of data, *GEOLOGICAL mapping, *HYDROTHERMAL deposits
Published
2022
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50. 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.

Author

Wypych, Alicja, Sicard, Karri R., Gillis, Robert J., Lande, Lauren L., Naibert, Travis J., Newberry, Rainer J., Twelker, Evan, Werdon, Melanie B., and Willingham, Amanda L.

Subjects
*GEOLOGICAL mapping, *GEOPHYSICAL surveys, *ROCK analysis, *FLUX (Metallurgy), *TRACE elements
Abstract

The article discusses the Division of Geological & Geophysical Surveys (DGGS) geochemical sampling project and geologic mapping in the Tok River area, Tanacross A-5 and A-6 quadrangles, Alaska in 2016. Topics including rock samples collection such as mineralized rock and igneous rock for trace-element geochemistry purposes, rock samples preparation by ALS Geochemistry, and sample type analysis using flux digestion and elemental tests.

Published
2016

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