Climate Forcing, Ocean Circulation, and the Geologic Record of Global Change Across the Cenomanian/Turonian Boundary, Western Interior Seaway of North America

在全球温暖、稳定的白垩纪沉积的地层保存了一项独特的自然实验记录，这将有助于我们更好地了解完整地球系统的动力学行为。西部内陆白垩纪海道(WIKS)的地层记录提供了一个无与伦比的研究机会，因为可以获得大量的数据集，这些数据集已经成熟，可以进行合成和分析。利用WIKS作为一个工作的“实验室”，我们建议：(1)了解全球气候系统及其在极端温暖时期的变异性；(2)验证气候模式，以适应与当今有本质不同的条件；(3)确定跨越C/T边界的WIKS对全球和区域强迫因子的海洋、生物和化学响应；以及(4)更好地确定这些海道响应与西部内陆盆地地质记录之间的联系。在这项研究中，一系列受不同WIKS数据集约束的分层大气和海洋模式模拟将被执行三次切片，代表主要的二阶海平面循环(Greenhorn Cycle)的不同阶段。对于每个时间切片，我们将：(1)从文献中确定全球古地理、古地形、海平面和大气PCO2；(2)使用NCAR社区气候模式(CCM)进行全球气候的基线数值实验；(3)进行一系列CCM对海平面变化、低地形和高地形、可变轨道参数和可变PCO2的敏感性实验；(4)利用逐日风应力和蒸发减去CCM的降水量来驱动一个三维湍流近岸海洋模式，研究WIKS对CCM变化的敏感性；(5)利用环流模型中的化学示踪剂和营养物、氧、盐度的箱模型，研究这些环流变化对有机碳的产生和碳、氧同位素的影响；以及(6)通过组合岩相图、底栖生物相/氧梯度图以及推断的温度、古盐度和有机碳分布图来检验这些预测。

Strata deposited during the globally warm, equable, Cretaceous period preserve the record of a unique natural experiment which will help us better understand the dynamical behavior of the integrated earth system. The stratigraphic record of the Western Interior Cretaceous Seaway (WIKS) provides an unparalleled opportunity for study because of the availability of substantial data sets that are ripe for synthesis and analysis. Using the WIKS as a working "laboratory" we propose to: (1) understand the global climate system and its variability during a period of extreme warmth; (2) validate climate models for conditions substantially different from the present day; (3) determine the oceanographic, biological, and chemical responses of the WIKS across the C/T boundary to both global and regional forcing factors; and (4) better define the links between these seaway responses and the geologic record of the Western Interior Basin. In this study a series of hierarchical atmospheric and ocean model simulations constrained by the diverse WIKS dataset will be performed for three times slices representing different stages of a major second order sea level cycle (Greenhorn cyclothem). For each time slice we will: (1) determine the global paleogeography, paleotopography, sea level, and atmospheric pCO2 from the literature; (2) perform baseline numerical experiments of global climate using the NCAR Community Climate Model (CCM); (3) perform a series of CCM sensitivity experiments to sealevel changes, low versus high topography, variable orbital parameters, and variable pCO2; (4) investigate the sensitivity of the WIKS to CCM variation by using daily wind stresses and evaporation minus precipitation from the CCM runs to drive a three-dimensional, turbulent flow, coastal ocean model; (5) investigate the influence these circulation changes might have on organic carbon production, and carbon and oxygen isotopes by following chemical tracers in the circulation model and developing box models of nutrients, oxygen, and salinity; and (6) test these predictions by assembling lithofacies maps, benthic biofacies/oxygen gradient maps, and maps of inferred temperature, paleosalinity and organic carbon distribution.