Timescales of South Atlantic ridge flank hydrothermal exchange; UK-IODP Moratorium Award for Thomas Belgrano - Shipboard Scientist, Expedition 393.

南大西洋洋脊侧翼热液交换的时间尺度；

• 批准号: NE/X003485/1
• 负责人: Damon Teagle
• 金额: $ 7.07万
• 依托单位: University of Southampton
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX003485%2F1
• 关键词: Timescales; South; Atlantic; ridge; flank

About two thirds of the Earth's surface is made up oceanic crust produced by tectonic plate spreading and magmatism along the global network of mid-ocean ridges. Chemical interaction between this newly formed ocean crust and seawater has regulated ocean chemistry throughout geological history. In particular, minerals precipitated in the crust from this interaction provide a means for geologically, biologically, and societally important substances such as carbon dioxide, water, sulfur, and potassium to be sequestered for many millions of years before eventual redelivery to the mantle.Despite this understanding, the rates and specifics of such uptakes by oceanic crust are not particularly well known, especially for 'middle aged' crust between 20-60 million years old. A well-known deficit between the amount of heat measured at the surface and that predicted by models based purely on conductive heat loss indicates that substantial seawater cooling of the crust occurs over this interval. Similarly, a measured gradual increase in the speed of seismic waves through oceanic crust over the same timeframe suggests mineral reactions continue over this middle aged period. Defining what these sub-surface changes are and how they develop with time - smoothly or in pulses, quickly or slowly - is prerequisite to integrating this component of the Earth system into global models for biogeochemical cycling. This study aims to determine the rate and the uniformity with which seawater-ocean crust exchange develops over the 20-60 million year stage of crustal maturation. The International Ocean Drilling Program (IODP) South Atlantic Transect Expeditions 390/393 were specifically planned to sample this age interval, with six drill holes into upper oceanic crust of 6-61 million years age. This will be achieved by dating the decay of natural, weakly radioactive elements in hydrothermal minerals. By dating material from all of the holes, we will assess whether hydrothermal fluid flow persisted over the 20-60 million time interval. Comparison of ages from drill holes with different thicknesses of blanketing sediments and different amounts of nearby basement outcrops will further allow the influence of these factors on prolonging hydrothermal circulation to be assessed. Finally, the chronological reference points for features in the drill core such as mineral veins will allow other expedition scientists studying the origin and microbial colonisation of these features to place their results in a temporal context.

大约三分之二的地球表面是由沿大洋中脊全球网络的构造板块扩张和岩浆作用形成的海洋地壳。这个新形成的海洋地壳和海水之间的化学相互作用在整个地质历史中调节着海洋化学。特别是，由于这种相互作用，地壳中沉淀的矿物质为二氧化碳、水、硫和钾等重要的地质、生物和社会物质提供了一种被隔离数百万年的手段，然后才最终被重新输送到地幔。尽管有了这样的认识，海洋地壳吸收碳的速率和具体情况还不是特别清楚，特别是对于年龄在2000万到6000万年之间的“中年”地壳。在地表测量到的热量与纯粹基于导热损失的模型所预测的热量之间有一个众所周知的差距，这表明在这段时间内，海水对地壳进行了大量冷却。同样，在同一时间范围内，地震波通过海洋地壳的速度逐渐增加，这表明矿物反应在这个中年时期仍在继续。定义这些地下变化是什么，以及它们如何随时间发展——平稳还是脉冲，快速还是缓慢——是将地球系统的这一组成部分整合到生物地球化学循环的全球模型中的先决条件。本研究旨在确定在2000 - 6000万年的地壳成熟阶段，海水-海洋地壳交换发展的速率和均匀性。国际海洋钻探计划（IODP）南大西洋样带探险390/393专门计划在这个年龄区间取样，在600 - 6100万年的海洋上部地壳中钻6个孔。这将通过测定热液矿物中天然弱放射性元素衰变的年代来实现。通过对所有孔洞的材料定年，我们将评估热液流体是否在2000万到6000万的时间间隔内持续流动。对比不同覆盖层厚度和附近基底露头数量的钻孔年龄，可以进一步评价这些因素对延长热液循环的影响。最后，钻芯中矿物矿脉等特征的时间参考点将允许其他考察科学家研究这些特征的起源和微生物定植，将他们的结果置于时间背景下。

项目成果

South Atlantic Transect

南大西洋横断面

• 发表时间: 2024
• 期刊: Proceedings of the International Ocean Discovery Program Expedition reports
• 作者: Coggon, R.M.;Teagle, D.A.H.;Sylvan, J.B.;Reece, J.;Estes, E.R.;Williams, T.J.;Christeson, G.L.
• 通讯作者: Christeson, G.L.

Expedition 393 Preliminary Report: South Atlantic Transect 2

• DOI: 10.14379/iodp.pr.393.2023
• 发表时间: 2023-01
• 期刊: International Ocean Discovery Program Preliminary Report
• 作者: D. Teagle;J. Reece;R. Coggon;J. Sylvan;G. Christeson;T. Williams;E. Estes

Expedition 390 Preliminary Report: South Atlantic Transect 1

• DOI: 10.14379/iodp.pr.390.2022
• 发表时间: 2022-10
• 期刊: International Ocean Discovery Program Preliminary Report
• 作者: R. Coggon;J. Sylvan;D. Teagle;J. Reece;G. Christeson;E. Estes;T. Williams