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

近年来，计算泥沙淤积速率(ARs)的第230条恒流代理(CFP)剖面法成为一个有争议的话题，尤其是关于泥沙聚焦及其量化的问题。在古海洋学研究中，根据一个人是使用年龄模型还是使用CFP来推导ARs，导致了截然不同的解释。根据这项裁决，PIS将调查沉积物再分配过程，以确定第230次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(IDPs)，以及其中包含的外星3He。在北大西洋不同和研究充分的沉积环境中230和3He的变化之间的一致，将进一步支持使用这两个CFP进行通量标准化。在沉积物聚焦和筛选量已知的地点产生的数据将有助于限制深海洋流对国内流离失所者和携带被吸附的230 Th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洞察。当结合14C和成对的3He和230次对沉积物细粒组分不同分离部分的测量时，PI将检验以下假设：1)3He对沉积物聚焦的敏感性低于230次，以及2)沉积物重新分配处理来自230次含沉积物部分的部分3He的程度。在未来，支持者希望开发一个新的指标(3He/230比)来反映深海洋流强度的变化与过去气候变化的关系。这个项目将让学生参与他们的教学、培训和学习。

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.