|Beebe black smoker image from previous HYBIS expedition|
The extraordinarily high pressure (of 500 x atmospheres) at the Beebe site, situated at nearly double the normal depth of most known hydrothermal systems, is important due to the physical changes that seawater undergoes at extremely high pressures and temperatures. Instead of being a liquid or vapour, the vent fluid becomes supercritical. These supercritical fluids are very reactive, dissolve metals at depth in the Earth’s crust, and transport them to the seafloor where they form spectacular hydrothermal vents and mineral deposits.
The Beebe site is also fascinating because it contains a history of hydrothermal activity represented by a series of older mounds. Sampling them will give us an idea of how the deposit has changed through time. The mineral deposits oxidise (like rusting) to a bright red colour, a process that greatly increases the concentration of valuable metals: a process known as ‘supergene enrichment’.
We are studying the Beebe site because it is a natural laboratory in which to study the effects of temperature and pressure on the composition of hydrothermal mineral deposits. Studying modern day hydrothermal systems like the Beebe Field allows us better to understand the formation of land-based ore deposits from which humankind gets all its essential metals.
By Matt Hodgkinson
|Verity teaches Matt a lesson|