Respuesta :

The particles are predominantly very fine-grained sulfide minerals formed when the hot hydrothermalfluids mix with near-freezing seawater. ... The cold seawater is heated by hot magma and reemerges to form the vents. Seawater in hydrothermal vents may reach temperatures of over 700° Fahrenheit 
evelina15

The answer is:

Friction heats the water as it seeps into holes and cracks on the ocean floor.