Geologic map of the Eagle A-1 Quadrangle, Fortymile mining district

Szumigala, D. J.; Newberry, R. J.; Werdon, M. B.; Athey, J. E.; Stevens, D. S. P.; Flynn, R. L.; Clautice, K. H.; Craw, P. A.

doi:10.14509/2863

Cited by 5 publications

(3 citation statements)

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“…3A-F). On the Pearce (1984) diagram they lie along the same trend. One difference between them is that the volcanic rocks have slightly lower Y and Nb concentrations compared to the Pika diorite (fig.…”

Section: Late Cretaceous Igneous Rocksmentioning

confidence: 57%

Geochemical interpretation of samples of igneous rocks from northeast Tanacross

Wypych¹

2020

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Section: Late Cretaceous Igneous Rocksmentioning

confidence: 57%

Geochemical interpretation of samples of igneous rocks from northeast Tanacross

Wypych¹

2020

View full text Add to dashboard Cite

Section: Late Cretaceous Igneous Rocksmentioning

confidence: 57%

Northeast Tanacross geologic mapping project, Alaska

2020

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“…Orthogneiss interlayered with metasedimentary units and amphibolites may have originated as sills or depositionally interlayered volcanic rocks. Volcanic protoliths were interpreted for fine-grained orthogneisses in this unit (Dusel-Bacon and others, 2015) and metavolcanics make up a significant portion of the correlative unit Mo in the adjacent Eagle Quadrangle (Szumigala, 2002). Zircon from undifferentiated orthogneiss in the Eagle A-1 Quadrangle yielded a U-Pb age of 343 ± 4 Ma (Day and others, 2002), and a sample from this map area yielded zircon age of 341.1 ± 2.3 Ma (Wypych and others, 2020).…”

Section: Orthogneiss (Mississippian To Devonian)-mentioning

confidence: 99%

Northeast Tanacross geologic map and map units and descriptions

Wypych¹,

Hubbard²,

Naibert³

et al. 2020

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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 (sheet 1). 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 Péwé 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 (2005aJackson ( , 2005b allowed comparisons with the distribution and character of deposits in Canada. Remotely Sensed ImagerySurficial geology was mapped by interpreting 2.5-m-resolution SPOT 5 color-infrared and natural color red-green-blue (RGB) imagery (©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. Field WorkWe conducted helicopter-supported surficial geology field work June 20-23, 2017, and July 3-4, 2018. During the field campaign we visited exposures and dug soil pits to examine material and gather information for unit descriptions and to check geologic mapping. We also measured the thickness of the active layer at several locations.

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Geologic map of the Eagle A-1 Quadrangle, Fortymile mining district

Cited by 5 publications

References 0 publications

Geochemical interpretation of samples of igneous rocks from northeast Tanacross

Geochemical interpretation of samples of igneous rocks from northeast Tanacross

Northeast Tanacross geologic mapping project, Alaska

Northeast Tanacross geologic map and map units and descriptions

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