Insights into hydrothermal iron flux variability at slow-spreading ridges from deep drilling data and reaction-transport modeling

通过深钻数据和反应输运模型深入了解缓慢扩张山脊的热液铁通量变化

• 批准号: 428603082
• 负责人: Professor Dr. Lars Helmuth Rüpke
• 金额: --
• 依托单位: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/428603082?language=en
• 关键词: Insights; into; hydrothermal; iron; flux

Recent discoveries in chemical oceanography point to hydrothermal iron as an important modulator of global scale biogeochemical ocean cycles, as iron availability often limits phytoplankton growth and thereby the biological carbon pump. Interestingly, these new results from the GEOTRACES program re-confirm the preceding realization within the mid-ocean ridge community that hydrothermal activity and thereby the hydrothermal export flux along the Mid-Atlantic Ridge (MAR) is disproportionally higher than its slow-spreading rate would suggest. Yet, the controls of hydrothermal iron export and how those vary between mafic and ultramafic geological settings remain poorly understood.Here, we will combine reaction-transport models with IODP data to identify the critical combination of parameters that results in the venting of the most saline and iron-rich fluids at the TAG and Rainbow hydrothermal fields. When seawater is heated while cycling through a hydrothermal system, it may split into a dense and saline brine phase and a lighter low salinity vapor phase upon intersecting with the two-phase boundary, with the metals accumulating in the brine phase. Tracking the brine phase throughout the circulation system that feeds the vent sites is therefore one key to an improved assessment. Quantifying the re-deposition of Fe in hydrothermal minerals around the upflow zone is another. We propose to return to the unique ODP 158 data on the basaltic-hosted fault-controlled TAG hydrothermal system and to integrate it with reaction-transport models to provide new insights into brine formation and iron transport. This work will be complemented by a study on the ultramafic-hosted Rainbow hydrothermal field, for which an international effort of submitting an IODP drilling proposal is on the way. From these two case studies, we anticipate fundamental new insights into the key controlling factors of brine formation and hydrothermal iron export at slow-spreading ridges, which is now realized to be so important for global biogeochemical cycles.

化学海洋学中的最新发现表明，水热铁是全球生物地球化学海周期的重要调节剂，因为铁的可用性通常会限制浮游植物的生长，从而限制生物碳泵。有趣的是，这些新的结果来自Geotraces计划，重新确认了中山山脊社区内的先前认识，即沿中大西洋山脊（MAR）沿着水热出口通量（MAR）远高于其慢速速度的速度不成比例。然而，对水热铁出出口的控制以及镁铁质和超镁铁质地质环境之间如何变化的控制仍然很少理解。在这里，我们将将反应传播模型与IODP数据结合在一起，以识别参数的关键组合，从而导致标签和彩虹水热场处的盐水和铁富富集的液体和铁富的流体。当海水在通过热液系统循环时加热时，它可能会分成致密和盐水盐水相，并在与两相边界相交时较轻的低盐度蒸气相，而金属在盐水相中积聚。因此，在整个循环系统中跟踪盐水阶段，以供应通风口位点，这是改进评估的关键之一。量化FE在上流区域周围的热液矿物中的重新沉积是另一个。我们建议返回到玄武岩托管故障控制的标签水热系统上的独特ODP 158数据，并将其与反应传输模型集成在一起，以提供有关盐水形成和铁运输的新见解。这项工作将通过对超弱托管彩虹水热场的研究来补充，为此，国际努力提交了IODP钻井建议。从这两个案例研究中，我们预计对缓慢散布的山脊下盐水形成和热液铁出口的关键控制因素的基本见解，这对于全球生物地球化学周期至关重要。