UK-IODP Moratorium Award for Lewis Grant - Shipboard Scientist Expedition 390: The role of ridge flank dolomitization in the ocean Mg budget

英国 IODP 暂停奖授予 Lewis Grant - 船上科学家第 390 次探险：山脊侧翼白云石化在海洋镁预算中的作用

• 批准号: NE/X002446/1
• 负责人: Damon Teagle
• 金额: $ 3.52万
• 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%2FX002446%2F1
• 关键词: UK; IODP; Moratorium; Award; Lewis

Ocean crust is created at submarine volcanic mid-ocean ridges and spreads away over time to form the ocean basins that cover two thirds of Earth's surface. Seawater circulates through cracks in the cooling crust, removing heat and chemically interacting with the rocks. This 'hydrothermal circulation' influences both the composition of the oceans and Earth through time. As the crust ages, sediment accumulates above it, and seawater flows along the contact between these sediments and the underlying crust, making this an important site for seawater-rock chemical exchange. Magnesium (Mg) is the second most abundant cation in seawater and is supplied to the oceans by rivers, before being removed during hydrothermal alteration of ocean crust and precipitation of Mg-rich carbonates (i.e., dolomite) in the sediments. These same processes also directly influence the global carbon budget, making Mg a useful proxy when reconstructing past climate change, which is key to understanding the future evolution of our planet.In the geological 'rock record', dolomite was a major store for oceanic Mg, although the extent of dolomite formation has decreased significantly over the last 150 million years. However, dolomite has been found within the sediments immediately overlying the volcanic crust, where hydrothermal fluid-rock exchange is occurring. It is important to decipher the timing, temperature, and the source of Mg of this dolomite formation to determine how and why it forms, and whether it is an important Mg reservoir. Mg isotopes provide a geochemical fingerprint of the source of the Mg in different reservoirs in the Earth. However, the Mg isotopic composition of dolomites formed close to the sediment-basement interface has not yet been determined.Scientific ocean drilling allows us to sample marine sediments and the oceanic crust buried deep below them. International Ocean Discovery Program (IODP) Expeditions 390 and 393 will drill a transect of six sites across the South Atlantic, recovering ocean crust formed at the Mid-Atlantic ridge between 7 and 61 million years ago and providing a unique opportunity to investigate dolomite formation along the contact between sediments and the ocean crust. I will use the recovered cores to reassess the Mg budget of the oceans over the last 60 million years and determine whether dolomite formation still exerts a significant control on modern seawater chemistry.

洋壳是在海底火山洋中脊形成的，随着时间的推移，洋壳逐渐扩散，形成了覆盖地球表面三分之二的海洋盆地。海水通过冷却地壳的裂缝循环，带走热量并与岩石发生化学反应。这种“热液循环”会随着时间的推移影响海洋和地球的组成。随着地壳年龄的增长，沉积物在其上方积累，海水沿着这些沉积物与下伏地壳之间的接触面流动，使这里成为海水-岩石化学交换的重要场所。镁（Mg）是海水中第二丰富的阳离子，并且在海洋地壳的热液蚀变和富镁碳酸盐（即，白云岩）中。这些过程也直接影响全球碳收支，使镁成为重建过去气候变化的有用替代物，这是了解地球未来演变的关键。在地质“岩石记录”中，白云石是海洋镁的主要储存，尽管白云石形成的程度在过去1.5亿年中显著减少。然而，在直接覆盖火山地壳的沉积物中发现了白云石，那里正在发生热液-岩石交换。重要的是要破译的时间，温度，镁的来源，以确定如何和为什么它的形成，以及它是否是一个重要的镁储层。Mg同位素提供了地球上不同储层中Mg来源的地球化学指纹。然而，在沉积物-基底界面附近形成的镁橄榄石的Mg同位素组成尚未确定，科学的海洋钻探使我们能够对海洋沉积物和深埋在其下的海洋地壳进行取样。国际海洋发现计划（IODP）第390号和第393号探险队将钻探横跨南大西洋的六个地点的横断面，恢复700万年至6100万年前在中大西洋海脊形成的洋壳，并提供一个独特的机会来研究白云石的形成。沉积物和洋壳之间的接触。沿着。我将使用回收的岩心来重新评估过去6000万年来海洋的镁预算，并确定白云石的形成是否仍然对现代海水化学产生重大控制。

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