Hydrothermal vent

Hydrothermal vents are special openings on the deep ocean floor where very hot water comes out. These openings are usually found where the Earth's plates are moving apart, like at mid-ocean ridges, or near places that are volcanically active. When the hot water from these vents mixes with the cold ocean water, it creates clouds of minerals that rise up into the water.

Around these vents, there are many interesting creatures that have adapted to the extreme conditions. Unlike most plants and animals that need sunlight, the life around hydrothermal vents depends on special tiny organisms that can use chemicals from the vents to make food. These organisms form the base of a unique food chain that supports animals such as giant tube worms, clams, limpets, and shrimp.

Scientists think that hydrothermal vents might have played an important role in the very beginning of life on Earth. The conditions inside these vents could help create the basic building blocks needed for life.

Physical properties

Hydrothermal vents in the deep ocean form where two tectonic plates move apart, like at mid-ocean ridges such as the East Pacific Rise and the Mid-Atlantic Ridge. The water in these vents is mostly seawater that is pulled into the system near volcanoes, mixed with water from deep inside the Earth.

This water comes out much hotter than the cold ocean around it—sometimes as high as 464 °C! Because of the pressure in the deep ocean, the water can stay liquid even at these high temperatures. Scientists are still learning how this affects the ocean and the life there.

Black smokers and white smokers

Some hydrothermal vents make tall towers from minerals. These towers can grow up to 60 meters high. One famous tower named “Godzilla” was 40 meters tall before it fell over.

Black smokers are special vents on the ocean floor that look like dark chimneys. They release hot water from deep inside the Earth, carrying minerals that make dark smoke. These vents were found in 1979 and are now known in many parts of the ocean. They can be very deep, with some found 5,000 meters below the surface.

White smokers are another type of vent that release lighter-colored minerals like barium, calcium, and silicon. They usually have lower temperature water because they are farther from the main heat source. Both black and white smokers can be found in the same area, but white smokers often appear later when the heat source moves away.

Hydrothermal plumes

Hydrothermal plumes are clouds of hot water that rise from places on the ocean floor where hot water bursts out. These places are called hydrothermal vents. The water from these vents is very hot and has different chemicals than the surrounding ocean water. As this hot water rises, it mixes with the colder ocean water.

Scientists can find these vents by looking for special gases in the water. One gas, called helium-3, comes from deep inside the Earth and helps show where vents are. These plumes also carry important metals like iron and manganese.

Biology of hydrothermal vents

Life usually needs energy from the sun, but deep-sea creatures cannot use sunlight. Instead, life around hydrothermal vents uses nutrients from chemicals and fluids around them. These areas have more life than the areas around them on the sea floor.

Hydrothermal vents support life through a process called chemosynthesis. Here, special bacteria use chemicals like hydrogen sulfide from vent water to make food. These bacteria are important because they feed many other sea creatures, creating rich ecosystems even without sunlight. The vents also add iron to the ocean, which helps tiny plants called phytoplankton grow.

Discovery and exploration

See also: Volcanogenic massive sulfide ore deposit

In 1949, a deep water survey found very hot water in the middle of the Red Sea. Later work in the 1960s showed hot, salty water and mud under the sea. This water was too salty for most living things.

In June 1976, scientists found the first evidence of underwater hot water spots along the Galápagos Rift, a part of the East Pacific Rise, during the Pleiades II expedition. In 1977, the first scientific papers about these hot water spots were published. In 1979, very hot water spots called “black smokers” were discovered. These spots shoot out hot water and minerals from tall chimneys. Scientists have been studying these areas ever since.

Distribution

Hydrothermal vents are found along the edges where Earth's plates move. They can also appear in special spots called hotspot volcanoes. As of 2009, scientists knew of about 500 places where these vents are active under the sea. Some of these places were seen directly, while others were found by looking at clues in the water or on the ocean floor.

Rogers and others, in 2012, identified at least 11 different areas where these vents are found:

1. Mid-Atlantic Ridge province,
2. East Scotia Ridge province,
3. northern East Pacific Rise province,
4. central East Pacific Rise province,
5. southern East Pacific Rise province,
6. south of the Easter Microplate,
7. Indian Ocean province,
8. four provinces in the western Pacific and many more.

Exploitation

Hydrothermal vents can create areas rich in important minerals like cobalt, gold, copper, and rare earth metals. These minerals are useful for making electronic devices. Companies are looking at ways to collect these minerals from the ocean floor.

Some countries, like Japan, are interested in getting these minerals from the sea because they need to import most of their minerals. Scientists and companies are working to understand how to mine these areas safely, caring about the effects on sea life and the environment.

Conservation

People have talked about protecting hydrothermal vents for 20 years. Sometimes, scientists who study these vents might accidentally damage them. There are rules about how scientists should behave, but no worldwide law to protect these special places.

One big concern is taking minerals from the deep sea, called deep sea mining. Four main minerals are being looked at for this: manganese nodules, cobalt-rich crusts, seafloor massive sulfides, and phosphorite nodules. Seafloor massive sulfides are found near hydrothermal vents and contain important minerals like iron sulfides. However, we do not know much about how taking these minerals will affect the vents. Scientists are also worried about how climate change, like ocean acidification and rising temperatures, might affect these vents and the animals that live there.

Geochronological dating

Scientists have special ways to find out how old hydrothermal vents are. They study minerals like sulfide and sulphate, such as pyrite and baryte. Two common ways to find the age are radiometric dating and electron spin resonance dating. Each method can be tricky, but they help us learn about the vents.

History and formation of hydrothermal vents

Further information: Alternative abiogenesis scenarios § Deep sea alkaline vents

Hydrothermal vents are places in the deep sea where hot water flows out from the Earth’s crust. Scientists have found many of these vents, but we still don’t know where all of them are because most of the ocean floor has not been explored. Many vents are found where the Earth’s tectonic plates move apart, called mid-ocean ridges.

Long ago, movements in the Earth’s crust caused gases, liquids, and sediments to burst out. This created large craters on the seafloor. Over time, these craters became home to hydrothermal vents. These vents have special features like layers of rock that dip inward and tall structures called chimneys. The hot water from these vents changes the chemistry of the surrounding area, creating a rich environment where unique tiny living things can survive.