Foraminiferal Paleoecology and Paleoceanography of the Cretaceous Western Interior Seaway: Northern San Juan Basin

浮游有孔虫种群结构的显著波动，特别是来自陆缘海洋的组合，被认为是导致水团性质变化的原因。白垩纪西部内陆海道代表了变化很大的水团对海平面波动、幕式构造作用和下沉以及气候变化的反应之间的动态界面。白垩纪海相层序富含有孔虫，是严格评价有孔虫古生态的难得机会。假设保存完好的有孔虫组合记录了水团边界的变化和/或水团性质的结构随时间的变化，PI将检验这一假设，即西部边缘的幕式海岸线迁移影响了海道的古海洋学，并可在近海泥岩相观察到。对浮游和底栖有孔虫种群结构的详细分析，结合粘土矿物学和其他沉积学和地球化学技术，将用于建立西部内海白垩纪有孔虫的可靠古生态模型。这些模型将有助于评估未勘探地区的资源潜力。

Marked fluctuations in the population structure of planktonic foraminifera, particularly in assemblages from epicontinental seas, are believed to recrod changes in water-mass properties. The Cretaceous Western Interior Seaway represented a dynamic interface between widely varying water masses responding to eustatic sealevel fluctuations, episodic tectonism and subsidence, and climatic variability. The Cretaceous marine sequences are rich in foraminifera and represent a rare opportunity to rigorously evaluate foraminiferal paleoecology. With the assumption that well-preserved foraminiferal assemblages recrod shifts in water mass boundaries and/or changes in water mass structure of properties through time, PIs will test the hypothesis that episodic shoreline migrations of the western margin influenced the paleoceanography of the seaway, and can be observed as such in offshore mudrock facies. Detailed analyses of planktonic and benthic foraminiferal population structure, coupled with clay mineralogy and other sedimentologic and geochemical techniques, will be used to develop robust paleoecologic models for Cretaceous foraminifera of the Western Interior Seaway. Such models will be useful for evaluating the resource potential of unexplored areas.