Models for Kerogen Oxidation, the Carbon Cycle, and Atmospheric Oxygen over Phanerozoic Time

显生宙时期大气氧水平的变化既是生物进化的主要原因也是主要结果，因此，研究这种变化对地球科学和生物科学都有重要意义。随着时间的推移，控制大气中O2水平的四个基本过程之一是沉积岩中有机物（干酪根）的氧化风化去除O2。我们建议建立理论模型，定量评价O2在干酪根风化速率和机制中的作用，并有助于确定这种风化速率的限制步骤是否仅仅是新鲜干酪根的物理侵蚀暴露。作为对模型的检查，我们将转向干酪根风化的现场测量，这是在我们之前的国家科学基金资助下完成的。此外，我们建议将现有的关于过去5.5亿年（显生宙）大气O2演化的简单模型与已经发表的关于大气CO2演化的复杂得多的模型结合起来，该模型考虑了山脉隆起、大陆漂移和气候变化等过程。结合我们的干酪根风化模型结果，我们希望能够建立一个完整的大气中氧气和二氧化碳的演化模型，并将这两种气体的变化与生物演化和气候变化联系起来。

ABSTRACTModels for Kerogen Oxidation, the Carbon Cycle,and Atmospheric Oxygen over Phanerozoic TimeChange over geologic time in the level of atmospheric oxygen is both a principal cause and principal effect of biological evolution, and, thus, study of such change is of interest to both the earth and biological sciences. One the four basic processes controlling the level of atmospheric O2 over time is the removal of O2 by the oxidative weathering of organic matter (kerogen) in sedimentary rocks. We propose to construct theoretical models to quantitatively evaluate the role of O2 in the rate and mechanism of kerogen weathering and help decide whether or not the rate limiting step in such weathering is simply the exposure of fresh kerogen by physical erosion. As a check on the modeling we will turn to the field measurements of kerogen weathering that have been done under our previous NSF grant. In addition, we propose to combine already existing simple models for the evolution of atmospheric O2 over the past 550 million years (Phanerozoic time) with an already published much more complex model for the evolution of atmospheric CO2 that considers such processes as mountain uplift, continental drift, and climate change. Combined with our model results on kerogen weathering, we hope to be able to construct a complete model for the evolution of both atmospheric oxygen and carbon dioxide and to relate changes in the two gases to biological evolution and climate change.