Collaborative Research: Actualistic Calibration of the Sphaerosiderite Paleoclimate Proxy

拟议的研究解决了需要的经验，现实主义的研究现代网站的成壤菱铁矿形成，可以测试简化的假设，用于在原始配方的sphaerosiderite古气候代理。球铁陨石代用品现在被用于验证地球历史上过去温暖时期的大气环流模式模拟（与NSF-ATM计划中的其他人合作研究），拟议的研究将减少这种地球化学代用品应用中的不确定性。拟议的研究将在现代成壤菱铁矿形成的选定地点进行实地调查，并将涉及：（1）土壤样品的野外和实验室表征;（2）现代成壤菱铁矿样品的稳定同位素分析;（3）地下水中菱铁矿、土壤有机质和溶解无机碳的放射性碳定年;（四）现场和实验室表征原位地质微生物学和地下水化学，以了解低温过程和稳定同位素现代水成土壤的实地调查建议沿着美国东部得克萨斯州和路易斯安那州的墨西哥湾沿岸，以及新泽西南部松林地的沼泽铁矿。选定的网站被选中，因为最近的菱铁矿形成的早期报告，或因为他们是密切类似于其他网站的菱铁矿formation.The更广泛的影响，这项调查将包括改善研究生和本科生的研究培训机会，从代表性不足的群体在贝勒大学和堪萨斯大学。本研究的科学价值将包括：（1）现代淡水菱铁矿形成的文献和精确定年;（2）对氧同位素组成之间的关系的仔细检查在菱铁矿形成的美国东部沿海测站，降水和地下水δ 18 O值的（δ 18 O）;（3）在一定的沉积温度范围内，对几个已发表的菱铁矿-水~（18）O分馏方程进行了经验确定;（4）增进对自然环境中低温菱铁矿形成所涉及的地球化学过程的了解;（5）为球铁古气候代用指标应用于目前正在开发的地球历史暖期大气环流模式模拟（在国家科学基金-大气环流模式方案中）开发一个改进的经验基础，从而推进基础大气研究。

The proposed research addresses a need for empirical, actualistic studies of modern sites of pedogenic siderite formation that can test the simplifying assumptions that were used in the original formulation of the sphaerosiderite paleoclimate proxy. The sphaerosiderite proxy is now being used for validation of General Circulation Model simulations of past warm periods in Earth History (collaborative research by others in the NSF-ATM program), and the proposed research would reduce uncertainties in the application of this geochemical proxy.The proposed research will carry out field investigations at selected sites where modern pedogenic siderite is forming, and will involve: (1) field and laboratory characterizations of sampled soils; 2) stable isotopic analyses of sampled modern pedogenic siderites; (3) radiocarbon dating of the siderite, soil organic matter, and dissolved inorganic carbon in the groundwater; (4) field and laboratory characterizations of the in situ geomicrobiology and groundwater chemistry to understand the low temperature processes and stable isotope fractionations related to siderite formation.Field investigations of modern hydromorphic soils are proposed along the U.S. Gulf coast in eastern Texas and Louisiana, and in the bog iron ores of the pinelands of southern New Jersey. Selected sites were chosen because of earlier reports of recent siderite formation, or because they are closely analogous to other sites of siderite formation.The broader impacts of this investigation will include improvements in the research training opportunities for graduate and undergraduate students from underrepresented groups at both Baylor University and the University of Kansas.The scientific merits of this study will include: (1) Documentation and precise dating of modern fresh water siderite formation; (2) Close examination of the relationship between the oxygen isotope composition (delta18O) of precipitation and groundwater delta18O values in coastal stations in the eastern United States where siderite is forming; (3) Empirical determination of the most appropriate of several published siderite-water 18O fractionation equations over a range of sedimentary temperatures; (4) Improved understanding of the biogeochemical processes involved in low-temperature siderite formation in natural environments; (5) Development of an improved empirical foundation for application of the sphaerosiderite paleoclimate proxy to currently developing general circulation model simulations of warm periods in Earth History (in NSF-ATM program), thereby advancing basic atmospheric research.