SGER:A test for modern carbon in Paleozoic paleosols

SGER：古生代古土壤中现代碳的测试

• 批准号: 0501690
• 负责人: Paul Schroeder
• 金额: --
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-15 至 2006-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0501690&HistoricalAwards=false
• 关键词: SGER; test; modern; carbon; Paleozoic

ABSTRACTThis project will test for the presence of modern carbon in goethite found in paleosols of the Upper Ordovician Neda Formation, in Neda, Wisconsin and Iowa. Factors that lead us to think there may be live carbon (14C) in these deposits include the development of the technology to measure carbon occluded in hydroxide soil minerals and the idea that post-depositional alteration of the Neda Formation has occurred. The outcome of this test will have important ramifications for the reliability of paleo-PCO2 proxy work and modeling. If modern carbon is found, then this must be reconciled with all the assumptions of previous work. If modern carbon is not found, then this gives added credence to assumptions of all previous work.Logistics involve (1) a short field expedition to sample paleosol ironstone in various locations in Neda, Wisconsin and Iowa, (2) extraction of the carbon from goethite using well established chemical/thermal decrepitating protocols, and (3) isotopic measurement of 12C, 13C, and 14C of all associated carbon phases. Laboratory work will be conducted at the University of Georgia Department of Geology Stable Isotope Laboratory and the Center for Applied Isotope Spectroscopy AMS facility. Funds will be used for (1) travel to collect samples and present results, (2) isotope mass spectrometry, and (3) a summer assistantship for a first-year Ph.D. student.Intellectual merit: This study integrates the recent discovery of modern carbon occlusion in soil minerals with the idea that ancient paleosols may undergo recrystallization while exposed to near surface weathering.Broader impact resulting from proposed activity: If modern carbon is found, then this must be reconciled with all the assumptions of previous paleo-PCO2 proxy work and modeling.

摘要 该项目将测试威斯康星州内达和爱荷华州上奥陶统内达组古土壤中发现的针铁矿中是否存在现代碳。导致我们认为这些沉积物中可能存在活性碳（14C）的因素包括测量氢氧化物土壤矿物中碳吸藏技术的发展以及内达地层沉积后蚀变已经发生的想法。该测试的结果将对古 PCO2 代理工作和建模的可靠性产生重要影响。如果发现现代碳，那么这必须与之前工作的所有假设相一致。如果没有发现现代碳，那么这就会增加之前所有工作的假设的可信度。后勤工作包括（1）在内达、威斯康星州和爱荷华州不同地点进行一次短途实地考察，对古土壤铁矿石进行采样，（2）从使用完善的化学/热爆裂方案对针铁矿进行分析，以及 (3) 所有相关碳相的 12C、13C 和 14C 同位素测量。实验室工作将在佐治亚大学地质系稳定同位素实验室和应用同位素光谱中心 AMS 设施进行。资金将用于（1）旅行收集样本和展示结果，（2）同位素质谱分析，以及（3）为一年级博士生提供暑期助学金。学生。智力价值：这项研究将最近在土壤矿物中发现的现代碳吸留与古代古土壤在暴露于近地表风化时可能会经历重结晶的想法结合起来。拟议活动产生的更广泛的影响：如果发现了现代碳，那么这必须与之前古 PCO2 代理工作和建模的所有假设相一致。