Timing and magnitude of C02 uptake by ocean crust through seawater interaction and carbonate veining

海洋地壳通过海水相互作用和碳酸盐脉纹吸收二氧化碳的时间和幅度

• 批准号: 49046519
• 负责人: Privatdozent Dr. Andreas Klügel
• 金额: --
• 依托单位: Fachgebiet Petrologie der Ozeankruste
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2010-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/49046519?language=en
• 关键词: Timing; magnitude; C02; uptake; ocean

Fluid flow within the flanks of mid-ocean ridges is now recognized as one of the principal processes that control the budgets of many elements in the oceans and the aging ocean crust on long time scales. This includes CO2 for which carbonate veins in basalt crust impose an important sink, yet little is known about the respective global flux. In over thirty years of ocean drilling, ocean crust of all ages has been sampled to depths that allow an assessment of CO2 uptake in the uppermost crust, but flux estimates exisit only for a few sites. Old crust indicates global oceanic uptake fluxes of 2-4•1012 moles CO2/yr, whereas young crustal sections indicate uptake rates that are an order of magnitude smaller. These observations can only be reconciled if the crust takes up CO2 continuously throughout much of its life time, which is at odds with seismic and heat flow evidence suggesting progressive sealing of permeability and virtual shut down of circulation in crust older than 20-50 Myrs. We propose that this major conundrum in ocean floor research can be resolved by comprehensive and systematic analyses of carbonate veins from crustal sections that cover a range of ages of both slow and fast spread crust. Our approach is fourfold:(1) Logging of core archives to establish carbonate vein crustal inventories, (2) determination of trace element abundances in carbonate veins by laser ablation ICP-MS to determine the maturity of fluids from which the carbonate precipitated, (3) Sr isotope dating by laser ablation MC-ICP-MS analyses of suitable carbonate veins, and (4) determination of geochemical changes in vein halos. The expected results will lead to better estimates of the global CO2 flux between ocean crust and oceans and to a more comprehensive understanding of the timing and processes involved in setting this flux. The data will be merged with isotopic data (Ca, Sr, O, C) to be obtained within the framework of a companion proposal.

现在，中山脊的侧面的流体流动被认为是控制海洋中许多元素和长期尺度上的海洋衰老预算的主要过程之一。这包括谷壳中碳酸盐静脉的二氧化碳，对各自的全球通量却一无所知。在三十多年的海洋钻孔中，所有年龄段的海壳已被采样到深度，以评估最上层地壳中的二氧化碳吸收，但仅在几个地点就存在通量估计。旧地壳表明全球海洋吸收通量为2-4•1012摩尔二氧化碳/年，而年轻的地壳切片表明摄取速率较小。这些观察结果只有在地壳在其整个生命的大部分时间内都不断地占据CO2时才能进行调和，这与地震和热流动证据不一致，表明在20-50 MYR的外壳中逐渐密封了渗透性和虚拟循环的循环。我们建议，可以通过对碳酸脉静脉的全面和系统分析来解决海底研究中的这一主要难题，这些碳酸盐静脉是涵盖较慢和快速扩散地壳的一系列年龄范围的碳酸盐静脉。我们的方法是四倍：（1）通过激光消融ICP-MS确定碳酸盐静脉中的碳酸盐静脉库存库存的核心档案记录，（2）确定碳酸盐的成熟度以确定碳酸盐的成熟度，（3）通过激光级别的MC-SRATE MC-SRATE ANLATE CRATIENTINS，（3）静脉光环的地球化学变化。预期的结果将导致更好地估计海壳和海洋之间的全球二氧化碳通量，并对设定此通量所涉及的时间和过程有更全面的了解。数据将与同位素数据（CA，SR，O，C）合并，将在伴侣建议的框架内获得。