Seafloor eruptions and evolution of hydrothermal fluid chemistry
Seafloor eruptions and evolution of hydrothermal fluid chemistry
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DOI：
10.1098/rsta.1997.0013
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发表时间：
1997-02-15
期刊：
影响因子：
5
通讯作者：
Delaney, JR
中科院分区：
文献类型：
--
作者：
Butterfield, DA;Jonasson, IR;Delaney, JR
地球化学家面临的一个主要挑战是如何将喷出的热液的化学性质与大洋中脊的局部或区域构造和火山状态联系起来。经过15年多的海底热液采样，温度和成分的时空变化的复杂情况正在显现。最近对确认最近有火山爆发的海脊段（胡安·德富卡海脊的同轴和北裂以及东太平洋海隆的北纬9-10度）进行了时间序列观测和取样，使人们对海底热液系统如何应对火山事件有了初步了解。相分离和增强的挥发性通量与火山爆发有关，在火山爆发后的最初阶段，以蒸汽为主的流体占主导地位，随后是以盐水为主的流体，这与海底以下暂时储存的盐水相一致。这里提供的同轴喷口的化学数据与这种演变是一致的。火山活动后热液产出量和组成的迅速变化可能对微生物生产、大型动物定居以及热液热量和质量通量产生深远影响。热源的大小和位置对于确定热量转移的速度以及海底微生物生产是否会蓬勃发展至关重要。同轴事件羽流可能是海底熔岩筑堤和喷发的直接结果。
A major challenge confronting geochemists is to relate the chemistry of vented hydrothermal fluids to the local or regional tectonic and volcanic state of mid-ocean ridges. After more than 15 years of sampling submarine hydrothermal fluids, a complex picture of spatial and temporal variability in temperature and composition is emerging. Recent time-series observations and sampling of ridge segments with confirmed recent volcanic eruptions (CoAxial and North Cleft on the Juan de Fuca ridge and 9-10 degrees N on the East Pacific Rise) have created a first-order understanding of how hydrothermal systems respond to volcanic events on the seafloor. Phase separation and enhanced volatile fluxes are associated with volcanic eruptions, with vapour-dominated fluids predominating in the initial post-eruption period, followed in time by brine-dominated fluids, consistent with temporary storage of brine below the seafloor. Chemical data for CoAxial vents presented here are consistent with this evolution. Rapid changes in output and composition of hydrothermal fluids following volcanic events may have a profound effect on microbiological production, macrofaunal colonization, and hydrothermal heat and mass fluxes. Size and location of the heat source are critical in determining how fast heat is removed and whether subseafloor microbial production will flourish. CoAxial event plumes may be a direct result of dyking and eruption of lavas on the seafloor.