CAREER : A Research and Education Plan in Global Biogeochemical Cycles: Seawater Calcium Isotopes and Carbonate Deposition History

通过对海洋重晶石中Ca含量和Ca同位素的研究，可以研究全球海洋地球化学循环，进而利用这些数据更好地了解海洋中Ca循环和CaCO 3沉积历史，并最终将其与构造和气候变化联系起来。这将是一个两部分的调查。首先，将箱形岩心顶部的重晶石的钙同位素组成（δ 44 Ca值）与现代海水的已知常数δ 44 Ca进行比较，以确定重晶石和海水之间的分馏，并评估这种分馏在一系列现代环境中的恒定性。然后，将利用现有的深海岩心以大约50万年的分辨率制作大约1.3亿年的重晶石三角洲44 Ca记录，在几个关键间隔内进行更高分辨率的采样。在教育方面，PI将在斯坦福大学开展以学生为中心的问题为基础的课程和全校范围的教育推广计划。这一研究领域可以提供有关钙的来源和汇的有价值的信息，包括碳酸盐的产生/埋藏和热液交换反应。鉴于碳酸盐和碳循环之间的联系，这项工作也可以产生对海洋pH值和大气CO2的长期历史的宝贵观点。

PaytanAbstractFunds are provided for a study of Ca concentrations and Ca isotopes in marine barite to study global biogeochemical cycles back to the last glacial maximum, and then use this data to better understand the Ca cycle and CaCO3 depositional history in the oceans and to ultimately relate them to tectonic and climate changes. This will be a two-part investigation. First, the calcium isotopic composition (delta 44Ca values) of barite in box core-tops will be compared with the known constant delta 44Ca of modern seawater to determine the fractionation between barite and seawater, and to evaluate the constancy of this fractionation in a range of modern environments. Then, a roughly 130 million year record of barite delta 44Ca will be produced, using existing deep-sea cores at a resolution of about 0.5 m.y., with higher-resolution sampling in a few key intervals. On the education side the PI will develop student-focused problem-based classes and a school-wide education outreach program at Stanford.This field of study could provide valuable information regarding the sources and sinks of Ca, including carbonate production/burial and hydrothermal exchange reactions. Given linkages between the carbonate and carbon cycles, this work could also yield valuable perspectives on the long-term history of ocean pH and atmospheric CO2.