What is source of hot water in deep sea thermal vents?

Question

What is source of hot water in deep sea thermal vents?

Answer 1

In some areas along the Mid-Ocean Ridge, the gigantic plates that form the Earth’s crust are moving apart, creating cracks and crevices in the ocean floor. Seawater seeps into these openings and is heated by the molten rock, or magma, that lies beneath the Earth’s crust. Magma is a complex high-temperature fluid substance. Temperatures of most magmas are in the range 700°C to 1300°C,

As the water is heated, it rises and seeks a path back out into the ocean through an opening in the seafloor.  As the vent water bursts out into the ocean, its temperature may be as high as 400°C (750°F).