Collaborative Research: Th-230 as a Sediment Focusing Indicator: constraints from He-3 in Interplanetary Dust Particles

合作研究：Th-230 作为沉积物聚焦指标：行星际尘埃粒子中 He-3 的限制

• 批准号: 0840430
• 负责人: Jerry McManus
• 金额: $ 9.12万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2009-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0840430&HistoricalAwards=false
• 关键词: Collaborative; Research; Th; 230; Sediment

Recently, the 230Th constant-flux proxy (CFP) profiling method of calculating sediment accumulation rates (ARs) has become a topic of significant controversy, especially with respect to the issue of sediment focusing and its quantification. Depending on whether one derives ARs using age models or CFPs leads to vastly different interpretations in paleoceanographic studies. Under this award the PIs will investigate sediment redistribution processes to determine the veracity of the 230Th CFP. They will measure another CFP with an independent source term, namely interplanetary dust particles (IDPs), and the extraterrestrial 3He contained therein. Agreement between 230Th and 3He variations in varied and well-studied depositional environments in the North Atlantic would constitute further support for the use of both CFPs for flux normalization. The data generated on sites with known amounts of sediment focusing and winnowing will help constrain the influence of abyssal currents on IDPs and the sediments carrying adsorbed 230Th, and will provide insights into the extent of hydrodynamic sorting of these particles. When combined with 14C and paired 3He and 230Th measurement on various separated fractions of the fine-grained component of the sediment, the PIs will test the hypotheses that 1) 3He is less sensitive than 230Th to sediment focusing, and 2) the degree to which sediment redistribution processes fractionate 3He-containing IDPs from the 230Th containing portion of the sediment. In the future, the proponents hope to develop a new proxy (3He/230Th ratio) for changes in the strength of deep-sea currents in association with past climatic changes. This project will involve students in their teaching, training and learning.

最近，计算沉积物堆积率（AR）的第230th恒定通量代理（CFP）剖面方法已成为一个重大争议的话题，特别是在沉积物聚焦及其量化问题方面。 根据是否使用年龄模型或 CFP 推导 AR 会导致古海洋学研究中截然不同的解释。 根据该奖项，PI 将调查沉积物重新分布过程，以确定第 230 个 CFP 的准确性。 他们将测量另一个具有独立源项的CFP，即行星际尘埃粒子（IDP），以及其中包含的外星3He。 北大西洋各种经过充分研究的沉积环境中 230Th 和 3He 变化之间的一致性将进一步支持使用两种 CFP 进行通量标准化。在已知沉积物聚集和风选数量的地点生成的数据将有助于限制深海流对 IDP 和携带吸附 230Th 的沉积物的影响，并将提供对这些颗粒的水动力分选程度的见解。当与 14C 结合并配对 3He 和 230Th 对沉积物细粒成分的各种分离部分进行测量时，PI 将检验以下假设：1) 3He 对沉积物聚焦的敏感性低于 230Th，以及 2)沉积物重新分布过程从沉积物的含 230Th 部分中分离出含 3He 的 IDP。未来，支持者希望开发一种新的替代指标（3He/230Th比率），用于反映与过去气候变化相关的深海洋流强度的变化。 该项目将让学生参与教学、培训和学习。