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

本研究的目的是建立北太平洋地区白垩纪沉积的年代地层和国际对比，并从产出的大型动物群分析中考虑北太平洋生物省的建立。为此，2002-2004年对美国太平洋沿岸的白垩纪海相沉积进行了国际野外考察。从岩石地层学、生物地层学和磁性地层学的角度对加州北部萨克拉门托河谷和阿拉斯加南部塔尔基特纳山脉广泛出露的海相白垩纪沉积(大谷层序)进行了研究。由于我们的野外和实验室研究先后收集了化石样品和沉积物岩心样品，建立了加州北部北福克棉花溪Barremian-Turonian层序的详细的巨型和微型体生物地层格架。在巴雷米统-下阿尔比统层序中识别出5个磁性地层阶段，即M5、M3、M1、M0r、C34n(具有M-1R反转层位)。这是北太平洋地区早、中白垩世高分辨率生物年代学和磁层序的首次报道。我们还发现了阿拉斯加南部塔尔基特纳山脉持续不断的高化石海相坎帕尼亚到马斯特里赫蒂安地层。

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.