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

最近，230 Th恒定通量代理（CFP）剖面法计算沉积物积累率（AR）已成为一个有争议的话题，特别是关于沉积物聚焦及其量化的问题。 根据是否得出AR使用年龄模型或CFPs导致在古海洋学研究中有很大不同的解释。 根据该奖项，PI将调查沉积物再分布过程，以确定230 Th 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）和其中包含的外星3 He。 230 Th和3 He之间的协议在不同的沉积环境和良好的研究在北大西洋的变化将构成进一步支持使用CFPs通量归一化。在已知沉积物聚集量和筛选量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吸附230 Th的沉积物的影响，并将提供对这些颗粒的流体动力学分选程度的见解。当结合14 C和配对的3 He和230 Th测量的沉积物的细粒组分的各种分离的馏分，PI将测试的假设，1）3 He是不敏感的比230 Th沉积物集中，2）沉积物再分布过程的程度，从沉积物的230 Th含有部分压裂含3 He的IDPs。今后，支持者希望开发一种新的代用指标（3 He/230 Th比率），以反映与过去气候变化有关的深海洋流强度变化。 该项目将使学生参与教学、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.