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Self-assembling porous precipitate structures

Self-assembling porous precipitate structures: Submarine hydrothermal vents

 

 

Chemical garden in a laboratory beaker showing the tubular growths of a variety of metal salts placed in a solution of sodium silicate. (From Cardoso SSS, Cartwright JHE. 2017 On the differing growth mechanisms of black-smoker and Lost City-type hydrothermal vents. Proc. R. Soc. A 473: 20170387. http://dx.doi.org/10.1098/rspa.2017.0387)

 

Three small (~30 cm tall) spires sitting on top of one of the chimneys in the Black Forest vent field at the Mariana arc.  Black, mineral-rich fluids at 240ºC are expelled into the ocean. Credit: NOAA (https://oceanexplorer.noaa.gov/gallery/livingocean/livingocean_seafloor.html#Anchor-Photos-37945).

 

Black smokers and Lost City-type springs are varieties of hydrothermal vents on the ocean floors that emit hot, acidic water and cool, alkaline water, respectively. While both produce porous precipitation structures as the issuing fluid encounters oceanic water, Lost City-type hydrothermal vents exhibit a more distributed flow in contrast to the open channels seen at acidic vents. Some basic questions about these systems include what determines the growth of the solid structure and how does the fluid flow interact with it. Both chemical diffusive transport and thermal diffusion across the vent walls play a role, but so does osmosis because the porous solid is semi-permeable to some solutes.  We are interested in exploring these interactions to understand the flows issuing from these vents and the solid structures confining them.