Hydrothermal circulation

Hydrothermal circulation is the movement of hot water within the Earth. The word comes from ancient Greek, where "hydor" means water and "therme" means heat. This process happens mostly near places where the Earth is warm, such as areas with volcanic activity.

You can find hydrothermal circulation close to the surface or deep inside the Earth. It may occur where faults—the cracks in the Earth's surface—allow water to move, or where hot granite forms deep underground. It can also happen during major mountain-building events known as orogeny or when rocks change under heat and pressure, a process called metamorphism.

This movement of hot water is important because it can create valuable mineral deposits. Over time, these deposits can become sources of important materials like copper, gold, and other metals, which are used in many things we use every day. Hydrothermal circulation is a key part of shaping the Earth's surface and creating natural resources.

Seafloor hydrothermal circulation

Hydrothermal circulation in the oceans is the movement of water through mid-oceanic ridge systems. This includes both hot water near the ridge crests and cooler water flowing through sediments and buried basalts farther away. In both cases, cold seawater sinks into the seafloor, gets heated deep down, and then rises back up because it becomes less dense.

Hydrothermal vents are places on the seafloor where this hot water mixes with the ocean. The most famous of these are natural chimneys called black smokers. The heat for the hot vents comes from newly formed basalt and, in the hottest vents, from an underlying magma chamber. The cooler vents are heated by older basalts that are still cooling.

Volcanic and magma related hydrothermal circulation

Hydrothermal circulation happens where there is heat from magma or volcanic vents near groundwater. This can create interesting features like geysers and hot springs. Scientists study these systems, especially where deep wells are used for geothermal energy.

Volcanic lakes show these processes well. Cold lake water seeps down, mixes with heated groundwater, and rises to form hot springs. These systems need a balance of cold water and geothermal heat to work, and they can create their own boundaries through gas release and mineral buildup.

Deep crust

Hydrothermal circulation is the movement of water inside the Earth's deep crust. It moves from hot rocks to cooler places. This process can happen because of magma, heat from radioactive rocks, heat deep inside the Earth, pressure from mountains like the Great Artesian Basin, and water released from certain rocks and sediments.

This movement helps create mineral deposits. Scientists study these deposits. They look at things like temperature and pressure, and where the water comes from, such as magma or seawater. Examples include porphyry copper deposits and Mississippi Valley-type deposits.