Chemical and Physical Studies of Hydrothermal Plumes at the Mid-Ocean Ridge Axis

东太平洋海底扩张轴线上的热液喷口产生了暖水的浮柱，这些浮柱上升并与海底水混合。这些羽状物是热液输出和热化学物质扩散的重要指标，也是寻找新喷口田的指南，但人们对它们的物理结构和其中发生的化学过程知之甚少。Drs。Mottl和Von Herzen开发了一种方法，可以在单个喷口场的规模上测量和表征热液和化学物质的通量，使用50米高的系泊仪器阵列，通过漂浮悬浮在潜水器ALVIN上方。该装置于1984年在东太平洋隆起成功测试，他们可以测量羽流的三维温度场，并通过透光率收集流速、电导率、压力和颗粒浓度的二维剖面。再加上从喷口上方不同高度冒出的含有悬浮黑色硫化物“烟雾”颗粒的水样。他们建议将这项技术应用于沿着胡安·德·富卡山脊10公里长的一段连续的喷口区域，作为物理、化学和地质观测综合项目的一部分。他们的目标是表征喷口区域羽流的物理和化学结构，并将其与羽流理论进行比较。估计由局部温泉和弥漫性暖泉喷发引起的喷口场和沿总段的化学通量和热通量，确定羽状物内发生的化学过程，并确定这些过程对热液输入命运的重要性。他们还将编制一份地质图，描述该热泉和相关的大量硫化物矿床。

Hydrothermal venting along axes of seafloor spreading in the eastern Pacific gives rise to bouyant plumes of warm water which rise and mix with ocean bottom waters. These plumes are an important measure of hydrothermal output and dispersal of both heat and chemicals, and an exploration guide for new vent fields, yet little is known about their physical structure or the chemical processes which occur within them. Drs. Mottl and Von Herzen have developed a method for measuring and characterizing the hydrothermal flux of heat and chemicals on the scale of an individual vent field, using a 50 m high moored instrument array suspended above the submersible ALVIN via flotation. With this device, which was tested successfully on the East Pacific Rise in 1984, they can measure the three-dimensional temperature field of a plume and collect two-dimensional profiles of flow velocity, conductivity, pressure, and particle concentration via light transmittance, plus samples of water containing suspended particles of black sulfide "smoke" from various heights above the vents. They propose to apply this technique to a series of contiguous vent fields along a 10 km segment of the Juan de Fuca Ridge, as part of an integrated program of physical, chemical, and geologic observations their objectives are to characterize the physical and chemical structure of the vent field plumes, to compare these with plume theory, to estimate the chemical and heat fluxes from the vent fields and along the total segment due to both localized hot spring and diffuse warm spring venting, to identify chemical processes occurring within the plumes, and to determine the importance of these processes for the fate of the hydrothermal input. They will also compile a geologic map and description of the vent field and associated massive sulfide deposits.