U-Pb zircon data for igneous units related to mineralization in the eastern Yukon-Tanana upland, eastern Alaska

From 2017-2019, framework metallogenic studies were completed in the eastern Yukon-Tanana upland in eastern Alaska. Numerous previously undated plutons known or suspected to contain components of porphyry, epithermal, and intrusion-related gold systems and associated deposit types were sampled for age and zircon trace element determinations between the Black Mountain area and the Yukon border, north of the Tanana River and south of the Yukon River. A collection of 54 samples were collected by Douglas Kreiner (USGS, Alaska Science Center). Zircon grains were separated from each sample. The samples were examined by U-Pb analysis by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) in a USGS laboratory in Denver, CO. The samples contain evidence of several discrete periods of magmatic activity, with concordant zircon dates that range from ca. 53.3-2727 Ma. The bulk of analyzed samples are between ca. 68-72 Ma. Other specific periods of magmatism based on zircon dates range from ca. 55 Ma, ca. 100-112 Ma, ca. 130 Ma, and ca. 180-211 Ma. The ca. 340-365 Ma dates are likely inherited from host rocks that were previously unidentified in the field area but are known in the regional framework geology. Archean and Proterozoic zircon dates are not common, but likely represent inheritance from sedimentary and metasedimentary protoliths from the region.