Collaborative Research: Interpreting the record of Antarctic sediment influenced by metal-rich hydrothermal deposits from their accumulation through early diagenesis and burial

南极地区被扩张中心包围，海底地区火山喷发和猛烈的热液喷发是典型的环境。热液喷口将金属释放到水柱中。作为一种自然资源，这些金属具有一定的经济价值，它们可以影响生物圈，包括影响在该区域占主导地位的动物组成和微生物过程。此外，热液金属与其他沉积物一起沉积到海底。海洋沉积物提供了一个了解过去的窗口，因为它们积累起来，每一层都包含有关沉积时海洋条件的信息。然而，随着热液在沉积物和洋壳中循环，沉积物中微量金属的数量和组成可能会发生变化，从而影响这一地质记录。该项目的目标是在R/V Polarstein号考察船的海上考察期间收集样本，并确定热液流体对沉积环境的影响。这一结果将加深我们对热液喷口如何影响沉积物中的地球化学信号以及它们在恢复古环境条件方面的应用的认识。该项目支持对一名研究生的培训。在过去几年中，在南大洋进行的几次考察的重点是重建地球上这一气候敏感区域的古海洋条件。在以前的工作中，沉积物中氧化还原敏感元素分布的变化被认为是揭示生产力和水柱中氧化还原条件随时间变化的有价值的工具。然而，富金属沉积物对这一古海洋记录的潜在影响仍未得到研究。该项目的目标是破译南极地区热液系统对经常用于古氧化还原重建的沉积痕迹金属特征的潜在影响。为此，我们将参加R/V Polarstein上的国际探险队(第119页)。将使用水下机器人制导的推芯和活塞芯回收热液沉积物和沉积物。沉积信号将与两个喷口热液中的痕量金属信号进行比较，并与该地区典型的富含远洋蛋白石的背景沉积物进行比较。为此，将在固相和孔隙水中分析硫、铁和锰相以及选定的微量金属。将对船上选定的成分进行样本分析。所有其他分析将在国内研究所进行，并将相应地准备和储存样品。这些数据将加深我们对初级代理信号的变化以及热液流体对这些代理信号的潜在影响的理解，因此可能对其作为热液输入附近地点的氧化还原代理的应用至关重要。此外，这些结果将补充在这个地点进行的平行计划研究，旨在了解热液喷口对这些极端环境中的动物组成和微生物过程的作用。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Antarctic region is surrounded by spreading centers, areas on the seafloor where volcanic eruptions and vigorous hydrothermal venting typify the environment. Hydrothermal venting releases metals into the water column. These metals are of some economic interest as a natural resource, and they can impact the biosphere, including affecting faunal composition and microbial processes that dominate in the region. Additionally, hydrothermal metals settle onto the seafloor along with other sediments. Marine sediments provide a window into the past as they accumulate, with each layer containing information about oceanographic condition at the time of their deposition. However, the amount and composition of trace metals in the sediment can change as hydrothermal fluids circulate through the sediment and oceanic crust, thereby impacting this geologic record. The goal of this project is to collect samples during a sea-going expedition on the research vessel R/V Polarstern and identify the impact of hydrothermal fluids on the sedimentary environment. The results will advance our knowledge on how hydrothermal vents impact the geochemical signals in sediment deposit and with that their application to reconstruct paleoenvironmental conditions. The project supports the training of a graduate student.During the last few years several expeditions in the Southern Ocean have focused on reconstructing paleoceanographic conditions in this climate-sensitive region of the planet. In this previous work, variations in redox-sensitive element distributions in the sediment were proposed as a valuable tool for unravelling changes in productivity and redox conditions in the water column over time. However, the potential effect of metal-rich sediment on this paleoceanographic record has remained unstudied. The goal of this project is to decipher the potential impact of hydrothermal systems in the Antarctic region onto the sedimentary trace metal signatures frequently applied for paleo redox reconstructions. For this purpose we will join an international expedition on the R/V Polarstern (P119). Hydrothermal deposits and sediments will be recovered using ROV-guided push cores and piston cores. The sedimentary signal will be compared with the trace metal signal in the hydrothermal fluids from two vent sites and background pelagic opal-rich sediment typical for this area. For this purpose, sulfur, iron and manganese phases and selected trace metals will be analyzed in the solid phase and pore waters. Samples will be analyzed for selected constituents onboard the ship. All other analyses will be carried out at home institutes and samples will be prepared and stored accordingly. The data will enhance our understanding of the alteration of primary proxy-signals and the potential impact of hydrothermal fluids on these proxies and could thus be crucial for its application as redox proxy for sites in vicinity to hydrothermal input. Additionally, the results will complement parallel planned research at this location aimed at understanding the role of hydrothermal vents on faunal composition and microbial processes in these extreme environments.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.