High-resolution chronostratigraphic and biofacies analysis of the marine Cretaceous on the North American Pacific coast

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This study has its aims to establish chronostratigraphy and international correlation of the Cretaceous deposits in the north Pacific regions as well as to consider the establishment of the north Pacific bioprovince from analysis of yielded macro faunas. For this purpose, international field expedition has been carried out in 2002-2004 for the marine Cretaceous deposits on the U.S.Pacific coast. The marine Cretaceous deposits (Great Valley Sequence) widely exposed along the Sacramento Valley, northern California and those in the Talkeetna Mountains, southern Alaska have been studied from the lithostratigraphic, biostratigraphic and magnetostratigraphic points of view. As a result of our field and laboratory studies successively collected fossil samples and sediment core samples, detailed mega-and microfossil biostratigraphic frameworks have been established for the Barremian to Turonian sequence in the North Fork Cottonwood Creek, northern California. Also, five magnetostratigraphic stages, i.e., M5,M3,M1,M0r,C34n (with M-1r reversal horizon) were recognized in the Barremian to Lower Albian sequence. This is the first report of the high-resolution Early to Middle Cretaceous biochronology and magnetostraligraphy in the North pacific regions. We have also recognized the continuous highly fossiliferous marine Campanian to Maastrichtiain strata from the Talkeetna Mountains, southern Alaska.