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

本提案所涉及的问题是深海碳酸盐沉积物中的溶解机制，这对于解释古气候记录和对碳酸盐泵在全球碳循环中的作用提供强有力的评估是至关重要的。这里建议的方法是美国国家科学基金会之前研究非均质碳酸盐溶解的NSF奖项的延伸。由于CaCO3和230Th对沉积物的降雨速率应随时间保持不变，因此，CaCO3的230Th归一化累积速率的变化应提供一个敏感而独立的指标来指示CaCO3的溶解。PI建议在一些精选的和具有良好特征的地点使用这一点(例如，西部Eq.Pac的Ontong-Java高原；西部的Ceara Rise)。情商。塞拉利昂隆起，东临佛得角高原。情商。ATL.)在过去的十年里，他对这些数据进行了采样。高空间分辨率(2-3 mm)230分析将与被认为控制CaCO3溶解的因素(如沉积物成分、沉积物混合速度、孔隙水化学、pH、溶解氧和有机碳等)进行对比。方解石在海底溶解的放射性碳(14C)年龄提供了一个百年至千年的时间尺度，用来观察和解释深海沉积记录中碳酸盐溶解的更复杂的混合模式。通过研究深海碳酸盐沉积堆积来解释过去的气候变化被认为是气候变化研究的重要组成部分。

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.