Geology and U-Pb zircon geochronology and Pb isotope geochemistry of mid-Cretaceous plutonic rocks in the Mount Nansen map area (NTS 115I/3 and part of 115I/2)

The geology in the Mount Nansen area, of the Dawson Range, comprises a metamorphic basement overlain and intruded by mid and Late Cretaceous magmatic rocks. Mid-Cretaceous epithermal deposits are recognized in the Brown-McDade cluster in the south, and Late Cretaceous porphyry and epithermal occurrences in the centrally located Klaza cluster. Here we report eight new U-Pb zircon crystallization ages, two CA-TIMS and six LA-ICPMS, and Pb isotopic data for igneous feldspar from six samples. A 199.06 ± 0.96 Ma crystallization age demonstrates the host rock to the Brown-McDade deposit is the Late Triassic to Early Jurassic Minto suite. We report crystallization ages of 111 ± 1.8 Ma for the Dickson Hill porphyry, 107.96 ± 0.03 and 107.86 ± 0.03 Ma for the central and border phases of the Bow Creek granite, respectively, and 107.0 ± 0.72, 107.0 ± 0.78 and 107.5 ± 0.67 Ma for equigranular and porphyritic phases of the Dawson Range granodiorite. These ages confirm a mid-Cretaceous Whitehorse suite affinity for these rocks with porphyritic textures suggesting high-level emplacement. Feldspar Pb isotopic data of igneous rocks in the Mount Nansen area become more radiogenic with time and are distinct for Late Triassic to Early Jurassic plutonic rocks versus Cretaceous rocks. Cretaceous feldspar isotopic data broadly overlaps Pb isotopic values of galena from deposits throughout the Dawson Range suggesting coeval magmatic rocks are a significant source of metals.

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Field	Value
Last Updated	October 20, 2025, 02:22 (UTC)
Created	October 20, 2025, 02:22 (UTC)
Domain / Topic Domain or topic of the dataset being cataloged.
Title Title for the Dataset.	Geology and U-Pb zircon geochronology and Pb isotope geochemistry of mid-Cretaceous plutonic rocks in the Mount Nansen map area (NTS 115I/3 and part of 115I/2)
Description A description of the dataset.	The geology in the Mount Nansen area, of the Dawson Range, comprises a metamorphic basement overlain and intruded by mid and Late Cretaceous magmatic rocks. Mid-Cretaceous epithermal deposits are recognized in the Brown-McDade cluster in the south, and Late Cretaceous porphyry and epithermal occurrences in the centrally located Klaza cluster. Here we report eight new U-Pb zircon crystallization ages, two CA-TIMS and six LA-ICPMS, and Pb isotopic data for igneous feldspar from six samples. A 199.06 ± 0.96 Ma crystallization age demonstrates the host rock to the Brown-McDade deposit is the Late Triassic to Early Jurassic Minto suite. We report crystallization ages of 111 ± 1.8 Ma for the Dickson Hill porphyry, 107.96 ± 0.03 and 107.86 ± 0.03 Ma for the central and border phases of the Bow Creek granite, respectively, and 107.0 ± 0.72, 107.0 ± 0.78 and 107.5 ± 0.67 Ma for equigranular and porphyritic phases of the Dawson Range granodiorite. These ages confirm a mid-Cretaceous Whitehorse suite affinity for these rocks with porphyritic textures suggesting high-level emplacement. Feldspar Pb isotopic data of igneous rocks in the Mount Nansen area become more radiogenic with time and are distinct for Late Triassic to Early Jurassic plutonic rocks versus Cretaceous rocks. Cretaceous feldspar isotopic data broadly overlaps Pb isotopic values of galena from deposits throughout the Dawson Range suggesting coeval magmatic rocks are a significant source of metals.
Tags / Keywords Keywords/tags categorizing the dataset.	Science and Technology ygs-import ygs-import-20250711 ygs-publications yukon-geological-survey
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Published Date Published date of the dataset.	2022-02-18
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Field	Value
Access category Type of access granted for the dataset (open, closed, service, etc).
License License used to access the dataset.	Open Government Licence - Yukon
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Location Location of the dataset.	https://open.canada.ca/data/en/dataset/731e7ca7-f83b-40ba-8338-9b1d5e953ec6
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Owner Owner of the dataset.	Government of Yukon | Gouvernement du Yukon
Contact Point Who to contact regarding access?	Yukon Geological Survey
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Publisher Email Email of the publisher.	[email protected]
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The Indigenous communities the dataset is about Indigenous communities from which data is derived.

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