This is a Non-Federal dataset covered by different Terms of Use than Data.gov.

40Ar/39Ar data from the Tok River area, Tanacross A-5 and A-6 quadrangles and adjoining areas, eastern Alaska Range

Metadata Updated: November 10, 2020

This report presents 40Ar/39Ar step-heating geochronology results for igneous and metamorphic rocks from the Alaska Division of Geological & Geophysical Surveys' (DGGS) geologic mapping project in the Tanacross A-5 and A-6 quadrangles and adjoining areas. Our results indicate the Hona granodiorite pluton intruded the area in the Late Cretaceous between 76 and 71 Ma. We determined Cretaceous metamorphic ages from 126 to 121 Ma for hornblende, biotite, sericite and muscovite from multiple samples of upper greenschist to amphibolite grade rocks. This is consistent with regional argon results that imply this area is in the upper plate of the Yukon Tanana Terrane (Hansen and Dusel-Bacon, 1998). Basaltic andesite dikes returned Late Cretaceous (99.0 +/- 0.5 Ma) and Tertiary (58.4 +/- 0.3 Ma) ages from biotite; these constrain late brittle faulting in the area. Finally, we obtained a Late Cretaceous age (71.5 +/- 0.5) for a basaltic andesite flow; these ages constrain the timing of displacement on some of the faults in the map area. Analyses were performed by the University of Alaska Fairbanks (UAF) Geochronology Laboratory, and results were reported by Jeff Benowitz and Paul Layer. 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 and Ca/K and Cl/K ratios.

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Non-Federal: This dataset is covered by different Terms of Use than Data.gov. License: No license information was provided.

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Dates

Metadata Date August 22, 2017
Metadata Created Date November 10, 2020
Metadata Updated Date November 10, 2020
Reference Date(s) January 1, 2017 (publication)
Frequency Of Update notPlanned

Metadata Source

Harvested from Alaska Division of Geological and Geophysical Surveys

Additional Metadata

Resource Type Dataset
Metadata Date August 22, 2017
Metadata Created Date November 10, 2020
Metadata Updated Date November 10, 2020
Reference Date(s) January 1, 2017 (publication)
Responsible Party Alaska Division of Geological & Geophysical Surveys (Point of Contact)
Contact Email
Guid
Access Constraints Use Constraints: 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., Access Constraints: This 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).
Bbox East Long -143.212748
Bbox North Lat 63.249459
Bbox South Lat 63.028463
Bbox West Long -144.300013
Coupled Resource
Frequency Of Update notPlanned
Licence The State of Alaska makes no expressed 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.
Metadata Language eng; USA
Metadata Type geospatial
Progress completed
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True
Temporal Extent Begin 2016-01-01
Temporal Extent End 2017-01-01

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