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.

大洋中脊的火山活动构成了地球上规模最大、最重要的化学分异过程之一。岩浆是由地幔选择性熔化产生的，将一些元素和元素比例带到地球表面，而将其他元素和元素比例留在地幔中。在迄今为止检查的所有潜在地球化学示踪剂中，铪 (Hf) 和钕 (Nd) 似乎是最有力的，不仅可以帮助我们了解地幔的化学演化，还可以帮助我们了解熔体分离和大洋中部的年龄和过程。山脊火山活动。这项研究将使用来自各个大洋中脊的深海橄榄岩样本，重点是最近发现的北极超缓慢扩张的加克尔海脊（Gakkel Ridge）的样本，那里的地幔岩石露头于海底。它将重点确定融化形成海底喷发的绝大多数火山岩的地幔源的比例。为了做出这一决定，将测量微量元素以及 Hf 和 Nd 同位素，其中 Hf 同位素阐明熔化过程，Nd 提供年龄限制。这项工作补充了 Gakkel 深渊橄榄岩的地球化学研究，但并不重叠。这项工作的更广泛影响包括对学生进行最先进的地球化学分析技术培训以及让高中生及其老师参与研究。它还将让高中参与者参与实验室及其活动。