U-Pb detrital zircon geochronology of Cretaceous-Cenozoic sedimentary rocks in the Ladue River-Mount Fairplay area, Alaska

This report presents U-Pb detrital zircon dates from three sedimentary rock samples collected in the eastern Tanacross Quadrangle during 2019 geologic mapping by the Alaska Division of Geological & Geophysical Surveys. This geologic map is published concurrently by Twelker and others (2021). The data were collected to support the map interpretation by establishing maximum depositional ages (MDAs) for the sampled strata. Further, these results also bolster a regional detrital zircon dataset that will, collectively, further constrain the Cretaceous-Cenozoic paleogeography of the region. This work is of economic and scientific interest: placer gold in the Fortymile District originated in Jurassic orogenic veins and, in some areas, was transported and concentrated by Cretaceous-Cenozoic depositional systems prior to its deposition in modern placer deposits. This process is described for the Coal Creek and Woodchopper Creek placers between Circle and Eagle and may be relevant elsewhere in the eastern Yukon Tanana Uplands. The analytical data tables associated with this report are available in digital format. Users can access the complete report and digital data from the DGGS website: http://doi.org/10.14509/30683.