High-Resolution 230Th Profiles in Carbonate Sediments: A Signal from Steady-State Dissolution?

碳酸盐沉积物中的高分辨率 230Th 剖面：来自稳态溶解的信号？

• 批准号: 0099016
• 负责人: William Martin
• 金额: $ 24.52万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0099016&HistoricalAwards=false
• 关键词: Resolution; 230Th; Profiles; Carbonate; Sediments

ABSTRACTOCE-0099016The problem being addressed in this proposal, dissolution mechanisms in deep sea carbonate sediments, is essential to the interpretation of paleo-climate records and to provide a robust assessment of the role of the carbonate pump in the global carbon cycle. The approach suggested here is an extension of the PI's previous NSF award investigating non-homogeneous carbonate dissolution. Since the rain-rates of CaCO3 and 230Th to sediments should remain constant over time, variations in the 230 Th normalized accumulation rate of CaCO3 should provide a sensitive and independent indicator of any variable CaCO3 dissolution.. The PI proposes to use this at a number of selected and well-characterized sites (e.g. Ontong-Java Plateau in western Eq..Pac; Ceara Rise in west. Eq. Atl; Sierra Leone Rise and Cape Verde Plateau in east. Eq. Atl.) which he has sampled during the past decade. Correlation of the high spatial resolution (2 -3mm) 230Th analyses with those factors thought to control CaCO3 dissolution (such as sediment composition, sediment mixing rates, pore water chemistry, pH, dissolved oxygen and organic carbon etc) will be undertaken for these sediment cores. Radiocarbon (14C) ages of calcite dissolving at the sea floor provides a centennial to millennial timescale with which to observe and interpret more complex mixing models for carbonate dissolution occurring in the deep sea sedimentary record. The interpretation of past climatic change through studying carbonate sediment accumulation in the deep ocean is recognized as being an important component of climate change research.

深海碳酸盐沉积物的溶解机制是解释古气候记录和评估碳酸盐泵在全球碳循环中作用的关键。这里提出的方法是PI之前研究非均质碳酸盐溶解的NSF奖励的延伸。由于CaCO3和230Th对沉积物的降雨速率应随时间保持恒定，因此CaCO3的2aco3标准化积累速率的变化应提供任何可变CaCO3溶解的敏感和独立指标。PI建议在一些选定的和具有良好特征的地点使用这种方法（例如，东部的onong - java高原，西部的Pac，西部的Ceara Rise）。Eq。Atl;东部为塞拉利昂高地和佛得角高原。Eq. Atl.)，他在过去十年中对其进行了采样。将对这些沉积物岩心进行高空间分辨率（2 -3mm） 230Th分析与那些被认为控制CaCO3溶解的因素（如沉积物组成、沉积物混合速率、孔隙水化学、pH值、溶解氧和有机碳等）的相关性。海底方解石溶解的放射性碳（14C）年龄为观察和解释深海沉积记录中发生的碳酸盐溶解的更复杂的混合模式提供了一个百年到千年的时间尺度。通过研究深海碳酸盐沉积来解释过去的气候变化是气候变化研究的重要组成部分。