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40Ar/39Ar data from the Richardson mining district, Big Delta Quadrangle, Alaska

Metadata Updated: November 10, 2020

During the 2017 and 2018 field seasons, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted geologic mapping and sampling in the Richardson mining district southeast of Fairbanks, including parts of the Big Delta B-4, B-5, B-6, and C-6 quadrangles. The project area has produced approximately 122,000 ounces of gold, mostly from placer mines, and it includes the Uncle Sam, Montecristo, Richardson, Tower, and Hilltop lode gold exploration properties. The goal of DGGS's work in this area is to conduct a mineral-resource assessment and to build an improved understanding of the area's geology and controls on gold mineralization to facilitate industry exploration targeting. The four 40Ar/39Ar ages reported here are all from samples at or near mid-Cretaceous intrusion-related gold prospects. Skarn hornblende from the Banner Creek area (18RN069) yielded an age of 104.0 +/- 1.6 Ma, which places its formation relatively early in the magmatic history of the district. Fine-grained, holocrystalline granodiorite in the immediate vicinity of the Democrat prospect yielded a biotite cooling age of 96.9 +/- 2.0 Ma (18RN568), slightly older than the white mica age reported for the nearby mineralized rhyolite dike (89.4 +/- 0.7 M). White mica from a sericite-pyrite altered, quartz-feldspar porphyry dike in the Rosa Pass area yielded an age of 87.0 +/- 1.5 Ma (17MBW526). Sericite-altered intrusive rock from drill core at the Lone Tree prospect yielded an age of 93.2 +/- 1.2 Ma (18ET057), somewhat younger than the 40Ar/39Ar age determined for presumably magmatic white mica from a dike at the nearby Naosi prospect on the Montecristo property (100.0 +/- 0.7 Ma). The complete report and digital data are available through the DGGS website: http://doi.org/10.14509/30530.

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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 September 11, 2020
Metadata Created Date November 10, 2020
Metadata Updated Date November 10, 2020
Reference Date(s) January 1, 2020 (publication)
Frequency Of Update notPlanned

Metadata Source

Harvested from Alaska Division of Geological and Geophysical Surveys

Additional Metadata

Resource Type Dataset
Metadata Date September 11, 2020
Metadata Created Date November 10, 2020
Metadata Updated Date November 10, 2020
Reference Date(s) January 1, 2020 (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 -146.160105
Bbox North Lat 64.526155
Bbox South Lat 64.301195
Bbox West Long -146.359570
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 2017-01-01
Temporal Extent End 2020-01-01

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