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Your search keyword '"Twelker, Evan"' showing total 26 results
26 results on '"Twelker, Evan"'

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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9. 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

10. 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

11. 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

12. 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

16. 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

18. 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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19. 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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20. 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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24. 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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25. 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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26. 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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