USGS Radiogenic Isotope Facility Personnel

Wayne Premo – Research Geologist

bio image of Wayne  Premo

Wayne’s research interests include secular marine chemical and isotopic changes, mineral deposit systems that formed in long-lived and reactivated continent-scale tectonic zones, temporal and tectonic evolution of crustal blocks within southern California and evolution of Proterozoic terranes of the central and southwestern United States.



Leonid Neymark – Research Chemist

bio image of Leonid  Neymark



Leonid’s area of expertise is isotope geochemistry and geochronology





Jim Paces – Research Geologist

bio image of James  Paces

Jim is engaged in various studies of climate change, landscape evolution, paleoseismicity, paleontology, and water sources/flow processes using U-series- and Sr-isotope data obtained from opaline silica, tufa, travertine, speleothems, bone, paleosols, peat, and water.




Kathleen Simmons – Geologist

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Front Range Isotope Group