GEOCHEMICAL TRACING OF BASALT PROVINCES IN THE EARLY HISTORY OF THE YELLOWSTONE HOT SPOT

Previous studies have linked the Miocene-aged Columbia River Basalt Group (CRBG) with the 17 Ma effusion of the Yellowstone hotspot. The paleolocation of the Yellowstone Hot Spot correlates to the divergent margins of the Kula, Farallon and Pacific plates, suggesting a potential plume component to the 60-50 Ma Crescent formation of the Olympic Peninsula and the 70 Ma Carmacks Group of the Yukon. The Crescent Formation shows a distinct geochemical relationship with the early-erupted members of the CRBG, supporting a plume component to Crescent volcanism and a potential common source region between the provinces. The trace element geochemistry of the Carmacks Group, however, lacks conclusive evidence in favor of correlation with the Yellowstone hotspot. In this study, new major and trace element data are presented for the Grande Ronde Basalts and for the upper member of the Crescent formation. Pb, Sr and Nd isotope analyses are reported for selected Crescent samples.