Subglacial Chemical Weathering under East Antarctica

东南极洲冰下化学风化作用

基本信息

批准号：
1744879
负责人：
Kathy Licht
金额：
$ 35.97万
依托单位：
Indiana University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-07-01 至 2024-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1744879&HistoricalAwards=false
关键词：
Subglacial Chemical Weathering under East

项目摘要

Nontechnical DescriptionChemical weathering is the process by which rocks and minerals are turned to clay, oxides, and chemical nutrients. Most of these weathering reactions consume atmospheric gases, such as oxygen and carbon dioxide, and therefore chemical weathering can drive natural, long-term changes in atmosphere chemistry. The nutrients released from rocks by chemical weathering are transported to the oceans and are necessary for the maintenance of life on Earth. The principal aim of this project is to assess how much chemical weathering occurs beneath Antarctica's largest ice sheet. Elsewhere in the world, chemical weathering is assessed by analyzing the outflow of rivers, but such direct measurements of chemical outflow are not possible because nearly all of Antarctica is covered by ice. In Antarctica investigators use samples from the Transantarctic Mountains where the interaction of flowing ice with mountain peaks causes rock and mineral material to emerge from the glacier base. This project will assess the degree to which this emerging mineral material has been chemically weathered compared to the underlying rock and the time scale at which such weathering occurs. Technical DescriptionPreliminary data from a Transantarctic Mountain site strongly suggests that the mineral products of chemical weathering (clays and oxides) are more abundant in the emerging material than in the underlying rocks. However, the chemical alteration of this material could have occurred recently or prior to glaciers forming in Antarctica. To constrain the timeline of weathering and thereby assess modern rates of weathering in Antarctica, this p[project will analyze two rare, radioactive isotopes within the weathered minerals. Because these isotopes are lost through radioactive decay, they act as clocks that can time the formation of the clays and oxides that form during chemical weathering. Minerals that pre-date the ice will have these isotopes clinging to their surface but not in their crystal structure. By first chemically removing the elements on the surface on the clays and oxides and then analyzing the minerals themselves, the project investigators will determine whether the minerals formed recently under the ice or beforehand in an ice-free environment. By calculating how recently these minerals formed and by analyzing the rate at which ice transports them off the continent, they will be able to calculate chemical weathering rates at locations up and down the Transantarctic Mountains. The result will be an estimate the impact of weathering under the East Antarctic ice sheet on the chemistry of the Earth's ocean nutrients. This research will provide valuable training for the next generation of polar scientists.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术描述化学风化是岩石和矿物转化为粘土、氧化物和化学养分的过程。大多数风化反应都会消耗大气中的气体，例如氧气和二氧化碳，因此化学风化可以驱动大气化学的自然长期变化。化学风化从岩石中释放的营养物质被输送到海洋，是维持地球生命所必需的。该项目的主要目的是评估南极洲最大冰盖下发生的化学风化程度。在世界其他地方，化学风化是通过分析河流的流出量来评估的，但这种直接测量化学流出量的方法是不可能的，因为几乎整个南极洲都被冰覆盖。在南极洲，研究人员使用来自横贯南极山脉的样本，其中流动的冰与山峰的相互作用导致岩石和矿物质从冰川底部出现。该项目将评估与底层岩石相比，这种新兴矿物材料被化学风化的程度以及这种风化发生的时间尺度。技术描述来自横贯南极山区的初步数据强烈表明，化学风化的矿物产物（粘土和氧化物）在新兴物质中比在下面的岩石中更丰富。然而，这种材料的化学变化可能发生在最近或在南极洲冰川形成之前。为了限制风化的时间表，从而评估南极洲的现代风化速率，该项目将分析风化矿物中的两种稀有放射性同位素。由于这些同位素会通过放射性衰变而丢失，因此它们充当时钟，可以对化学风化过程中形成的粘土和氧化物的形成进行计时。早于冰形成的矿物会将这些同位素附着在其表面，但不在其晶体结构中。通过首先用化学方法去除粘土和氧化物表面的元素，然后分析矿物质本身，项目研究人员将确定这些矿物质是最近在冰下形成的还是之前在无冰环境中形成的。通过计算这些矿物的形成时间和分析冰将它们运出大陆的速率，他们将能够计算横贯南极山脉上下位置的化学风化率。结果将估计东南极冰盖下的风化对地球海洋营养物质化学的影响。这项研究将为下一代极地科学家提供宝贵的培训。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（3）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Meteoric 10Be speciation in subglacial sediments of East Antarctica

东南极洲冰下沉积物中的流星 10Be 形态

DOI：
10.1016/j.quageo.2023.101458
发表时间：
2023-07
期刊：
Quaternary Geochronology
影响因子：
2.7
作者：
Arnardóttir, Eiríka Ö.;Graly, Joseph A.;Licht, Kathy J.;Bish, David L.;Caffee, Marc W.
通讯作者：
Caffee, Marc W.

Chemical weathering signatures at Mt. Achernar, Central Transantarctic Mountains II: Surface exposed sediments

横贯南极山脉中部阿赫纳尔山的化学风化特征 II：地表暴露沉积物

DOI：
10.1016/j.gca.2022.06.024
发表时间：
2022-06
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
Graly, Joseph A;Licht, Kathy J;Bader, Nicole A;Kassab, Christine M;Bish, David L;Kaplan, Michael R
通讯作者：
Kaplan, Michael R

Chemical weathering signatures from Mt. Achernar Moraine, Central Transantarctic Mountains I: Subglacial sediments compared with underlying rock

跨南极山脉中部阿赫纳尔冰碛山的化学风化特征 I：冰下沉积物与下伏岩石的比较