Collaborative Research: Hf-Isotopes as Tracers of Highly Depleted Oceanic Mantle

合作研究：铪同位素作为高度耗尽的大洋地幔的示踪剂

基本信息

批准号：
1155721
负责人：
Henry Dick
金额：
$ 13.53万
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：
2012
资助国家：
美国
起止时间：
2012-02-15 至 2015-01-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1155721&HistoricalAwards=false
关键词：
Collaborative Research Hf Isotopes Tracers

项目摘要

Volcanic activity on mid-ocean ridges constitutes one of the largest scale and most important chemical differentiation processes on earth. Magmas, created from the selective melting of Earth's mantle, bring some elements and elemental ratios to Earth's surface and leave others behind as residues in Earth's mantle. Of all the potential geochemical tracers examined to date, Hafnium (Hf) and Neodymium (Nd) appear to be the most powerful in helping us understand not only the chemical evolution of the mantle but also the ages and process of melt segregation and mid-ocean ridge volcanism. This research will use samples of abyssal peridotite from various mid-ocean ridges, emphasizing samples from the recently discovered ultra-slow spreading Gakkel Ridge in the Arctic, where mantle rocks outcrop on the seafloor. It will focus on determining the fraction of the mantle source that melts to form the vast majority of volcanic rocks erupted on the seafloor. To make this determination, trace elements and Hf and Nd isotopes will be measured, with the Hf isotopes illuminating the melting process and Nd providing age constraints. This work complements, but does not overlap with, a geochemical study of Gakkel abyssal peridotites. Broader impacts of the work include student training in state-of-the art geochemical analytical techniques and engaging high school students and their teachers in the research. It will also involve the high school participants in the laboratory and its activities.

海洋中脊上的火山活动构成了地球上最大和最重要的化学分化过程之一。岩浆是由地球地幔选择性融化产生的，将一些元素和元素比带到了地球表面，并将其他元素比作为地球披架的残留物抛在后面。在迄今为止检查的所有潜在地球化学示踪剂中，Hafnium（HF）和Neododimium（ND）似乎是最有力的，它不仅可以帮助我们了解地幔的化学演化，而且还可以理解融化隔离的年龄和过程。这项研究将使用来自各种海洋山脊的深渊橄榄岩样品，强调来自最近发现的北极地区超慢的gakkel山脊的样品，在海层上地幔岩石露出海底。它将着重于确定地幔源的比例，这些地幔源融化，形成在海底爆发的绝大多数火山岩。为了做出这一确定，将测量痕量元素以及HF和ND同位素，HF同位素照明熔融过程并提供年龄约束。这项工作是对Gakkel Abyssal橄榄岩的地球化学研究的补充，但并不重叠。这项工作的更广泛影响包括在最先进的地球化学分析技术中培训学生，并吸引高中生及其老师参与研究。它还将涉及实验室及其活动的高中参与者。