S-EPR: Biogeochemical Evolution in Intense Hydrothermal Plumes Emanating from a Superfast Spreading Center

在加勒特变换和复活节微板块之间的南东太平洋隆起(S EPR)段是全球海脊系统中扩张速度最快的地区之一，也是迄今研究过的所有大洋中脊(MOR)系统中最强烈的热液活动地点，反映在喷口和水柱的密度上。法国和日本/美国(PMEL NOAA)最近对该地区的潜水艇和水面舰艇访问发现，在14/50‘到18/40’之间，热液羽流覆盖了超过60%的海脊。此外，喷口流体化学成分的剧烈变化导致羽流水域出现了明显和不寻常的特征。S EPR这一段的热液系统具有强烈的、几乎连续的和动态的性质，为全球海脊系统对海洋地球化学和生物圈的任何地方提供了最集中的影响。集中在该系统的热液喷发和羽流的研究工作将通过两个由美国国家科学基金会资助的合作项目继续进行。M.Lilley、K.Von Damm和J.Lupton已获得资助，将在S EPR上执行25次潜水计划，重点是从17公尺以南几个已记录的喷口区域收集喷口流道。S.R.Collier已获得资金，将对热液喷口特征的潜水观测扩展到局部(喷口区域)的水柱热液羽流。此外，日本/太平洋海洋和大气层管理局正在继续对加勒特南部EPR轴线上热液喷发/羽流的分布和组成进行跨学科的联合调查。与上述资助项目合作，将对S EPR强烈热液羽流的地球微生物学进行研究。本提案的目标高度补充并将扩展Lilley/Collier计划的主要目标；这些研究将评估不断演变的羽流中微生物种群和生物地球化学过程的变化率。与日本太平洋海洋和大气层管理局(海脊通量)S项目合作，将能够确定一些相同地点的典型热液矿物和有机碳垂直通量，并将这些通量与热液成分的生物地球化学转化速率以及含金属沉积物的分布和积累速率联系起来。转变过程和通量速率的分析和解释将与M.Lilley(UW)(以及K.Von Damm和J.Lupton)、R.Collier(俄亥俄州立大学)、日本(T.Urabe、J.Ishibashi、H.Kawahata、K.Marumo、A.Marnya na及同事)和PMEL/NOAA(E.Baker、R.Feely、G.Massoth、D.Butterfield及同事)密切合作完成。

The section of the southern East Pacific Rise (S EPR) between the Garrett Transform and the Easter Microplate has one of the fastest spreading rates on the global ridge system and is the locus of the most intense hydrothermal activity, reflected in the density of venting sites and in the water column plumes, of all mid-ocean ridge (MOR) systems studied to date. Recent submersible and surface ship visits to this region by the French and Japanese/American (PMEL NOAA) have revealed that hydrothermal plumes overlay over 60% of the ridge crest between 14Ý50' and 18Ý40' S. Furthermore, dramatically variable vent fluid chemistries result in distinct, and unusual signatures in the plume waters. The intense, nearly continuous, and dynamic nature of the hydrothermal system over this section of the S EPR provides for the most focused impact anywhere of the global ridge system on the ocean geochemistry and biosphere. Research efforts focused on the hydrothermal venting and plumes of this system will continue with two NSF funded collaborative projects. M. Lilley, K.Von Damm, and J. Lupton have been funded to perform a 25 dive submersible program on the S EPR, focusing on the collection of vent fluds from several regions of documented venting south of 17ÝS. R. Collier has been funded to extend the submersible observations of the hydrothermal vent characteristics to the water column hydrothermal plume at the local (vent field) to segment scale. In addition, the Japanese/PMEL NOAA are continuing their joint, interdisciplinary investigation of the distribution and composition of hydrothermal venting/plumes along the EPR axis south of the Garrett. A study of the geomicrobiology of the intense S EPR hydrothermal plumes will be made in collaboration with the above funded programs. The goals of the present proposal are highly complementary to and will extend the primary goals of the funded Lilley/Collier programs; these studies will assess the rate of change of microbial populations and biogeochemical processes in an evolving plume. Collaboration with the Japanese/PMEL- NOAA (RIDGE Flux) S EPR project will allow the determination of representative hydrothermal mineral and organic C vertical fluxes at some of the same sites and to relate these fluxes to biogeochemical transformation rates of hydrothermal constituents and metalliferous sediment distributions and accumulation rates. Analyses and interpretation of transformation processes and flux rates will be completed in close collaboration with M. Lilley (UW) (and K.Von Damm and J. Lupton), R. Collier (OSU), Japanese (T.Urabe, J. Ishibashi, H. Kawahata, K. Marumo, A. Marnyarna, and colleagues) and PMEL /NOAA (E. Baker, R. Feely, G. Massoth, D. Butterfield and colleagues) scientists.