Hydrothermal Vents Flashcards
How does mantle convention cause seafloor spreading
The mantle churns in circular convection currents and this drags tectonic plates along allowing the seafloor plates to spread apart
Movement of plates at a divergent boundary
Moving away from eachother
Mid-ocean ridge
Divergent boundary that allows magma to reach surface and seafloor spreading
65% of vents are on this
How do hydrothermal vents form?
seawater percolates down through fissures is crust
seawater is heated by magma and reemerges
As the seawater is heated some chemicals are removed (Mg, SO2), and others are transferred from crust to water (S, Cu, Zn, Fe)
Super-heated metal-infused hydrothermal fluids rise and mix with near-freezing seawater
Rapid chemical reactions cause S and other chemicals to precipitate
Precipitate forms chimneys and mineral rich deposits on the seafloor
How are unknown vents discovered?
Imaging
CTD profiles
Water samples
Direct Visualisation
How many vents discovered
Currently 600 discovered but research suggests 700 more on mid-ocean ridge alone
What is chemosynthesis
synthesis of organic compounds using energy derived from reactions of inorganic molecules, in the absence of light
Hydrothermal sulfur chemosynthesis
Oxidize hydrogen sulfide, add O2 and CO2 to produce sugar (CH2O) sulfur (S) and water (H2O)
Steps of hydrothermal vent chemosynthesis
Hot water from vents is saturated with dissolved chemicals
Microbes absorb hydrogen sulfide and carbon dioxide from vent and oxygen from water
Microbes use the energy released from oxidizing sulphur to make organic molecules
Microbes grow and reproduce, and are eaten by an animal or hosted as internal symbionts
Vent-associated polymetallic sulfides
Largely base metal (Cu, Zn, Fe, Pb)
Precipate from hydrothermal fluid
These are of interest for mining
Environmental risks to mining vents
Destruction of habitat
Sediment plumes (smother)
Waste water
Noise and light pollution
Marine biopharmaceuticals
35 000 compounds known and 1000 discovered yearly
