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Zircon Trace Element Data for Igneous Units Related to Mineralization in the Eastern Yukon-Tanana Upland and nearby areas, Eastern Alaska

May 20, 2022

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. These geochronologic data are reported in a separate USGS data release. The zircon samples were later analyzed for trace element characteristics by Douglas Kreiner using the Sensitive High Resolution Ion Microprobe with Reverse-Geometry (SHRIMP-RG) at the Stanford-USGS laboratory in Palo Alto, California. The samples represent several discrete periods of magmatic activity, ranging from 56.5-360.3 Ma. The Paleozoic ages are of host rocks that were previously unidentified and collected for regional framework geology. The bulk of analyzed samples are between 68-72 Ma. Other specific periods of mineralization range from 100-112 Ma and 180-211 Ma.

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