Mantle plume

Deep inside the Earth, things get very hot.

Very hot material forms near the center. This hot material rises up through the middle of the Earth. It looks like a big bubble.

These bubbles are shaped like mushrooms. They have a long, thin neck. They also have a wide head.

When the bubble gets close to the top, it melts. This melted rock rises to the surface. It can make volcanoes.

These volcanoes can form long chains of islands. This is how some islands in the sea were made.

Deep inside the Earth, heat moves in a special way.

Scientists call these moving parts mantle plumes. They start at the core-mantle boundary. This is the place where the hot core meets the mantle. The core is very hot. It is about 1,000 degrees Celsius hotter than the mantle.

This heat makes material rise up.

A plume looks like a mushroom. It has a long, thin neck. It also has a wide head. This head grows as it rises. The head can be 2,000 km wide.

When the plume head hits the top layer of the Earth, it flattens out. This causes the rock to melt. This melting makes magma. The magma rises to the surface to form hotspots.

Hotspots can make many volcanoes. Some form long chains of islands. The Hawaiian Islands are a great example. As the Earth's crust moves, the plume stays in one place. This leaves a trail of old volcanoes behind. Some plumes also make huge areas of lava called flood basalts. These can happen in the ocean or on land.

Deep inside our planet, heat moves in a way that shapes the world above. Scientists use the term mantle plume to describe these rising columns of hot material. These plumes help move energy from the Earth's deep interior to the surface. They are a key part of how the Earth stays active. Without this heat transfer, our planet would look very different.

A plume begins at the core-mantle boundary, which is about 3,000 km deep. At this boundary, the core is about 1,000 degrees Celsius hotter than the mantle. This heat makes the material more buoyant, so it starts to rise. The plume looks like a mushroom with a long, thin neck and a wide head. As the head rises, it can expand to about 2,000 km in diameter.

When the head hits the upper layer of the Earth, it flattens out and melts. This process, called decompression melting, creates huge amounts of magma.

People first thought about these plumes many years ago. J. Tuzo Wilson proposed the idea in 1963. Later, W. Jason Morgan developed the idea further in 1971 and 1972. Scientists even used small fluid-filled tanks to simulate plumes in the early 1970s. These experiments helped show how the mushroom shape works. Now, computers use numerical modelling to predict how these plumes behave.

Mantle plumes create famous volcanic sites called hotspots. One famous example is the Hawaiian-Emperor seamount chain in the Pacific Ocean. As a tectonic plate moves over a fixed plume, it leaves a trail of old volcanoes. Plumes can also cause massive eruptions called flood basalts. These have created the Deccan Traps in India and the Siberian Traps in Asia. In the ocean, they form large areas like the Ontong Java Plateau.

You can think of a mantle plume like a hot air balloon. The heat at the bottom provides the lift to make it rise. Just as a balloon moves upward through the air, the plume moves through the mantle. Some scientists use special gases to track these plumes. They look for Helium-3, which is a gas from the Big Bang. Finding this gas helps prove that the material came from very deep inside the Earth.

A mantle plume is a proposed mechanism for convection within the Earth's mantle. This process helps explain why certain areas of the planet experience unusual volcanic activity. Scientists believe these plumes transport heat and material from the deep interior to the surface. They are part of a larger system that moves energy through the Earth. While most volcanic activity happens at the edges of tectonic plates, plumes explain why volcanoes appear in other places.

The process begins at the core-mantle boundary, located about 3,000 km deep. This boundary is a major thermal discontinuity, meaning there is a sharp change in temperature. The Earth's core is approximately 1,000 degrees Celsius hotter than the overlying mantle. Because this material is super-heated, it becomes more buoyant. This buoyancy causes the material to rise through the mantle in a narrow column.

Researchers describe the structure of a plume as resembling a mushroom. It consists of two distinct parts: a long, thin conduit and a bulbous head. The conduit is a narrow vertical channel that connects the plume base to its top. As the plume rises, the head expands in size. This happens because the hot material moves upward through the conduit faster than the plume itself rises through the surrounding mantle. The bulbous head can reach a diameter of about 2,000 km.

When the plume head reaches the base of the lithosphere, it flattens out against this barrier. This contact leads to decompression melting. This occurs because the material rises to shallower depths where there is less pressure. This melting creates large volumes of basalt magma. This magma may then erupt onto the surface. Numerical modelling suggests these eruptions can last for several million years.

The concept of mantle plumes has a clear history of scientific development. J. Tuzo Wilson first proposed the idea in 1963. W. Jason Morgan further developed the theory in 1971 and 1972. In the early 1970s, scientists used laboratory experiments with small fluid-filled tanks to simulate these plumes. These experiments showed that thermal or compositional plumes could be modeled using fluid dynamics. Today, scientists use the transient instability theory of Tan and Thorpe to predict plume size and occurrence. This theory suggests a cycle time of about 2,000 million years between plume formation events.

Mantle plumes are responsible for several massive geological features. They create volcanic hotspots, such as the one beneath Hawaii. As a tectonic plate moves over a plume, it creates a time-progressive chain of volcanoes. The Hawaiian-Emperor seamount chain is the most famous example of this. Plumes also cause large igneous provinces through flood basalts. Notable examples include the Deccan Traps in India and the Siberian Traps in Asia. In the ocean, these processes create oceanic plateaus, like the Ontong Java Plateau in the western Pacific.

Scientists use several methods to study these deep processes. They look at the chemical and isotopic composition of basalts. For example, they track the ratio of Helium-3 to Helium-4. Helium-3 is a primordial isotope formed during the Big Bang. Finding high ratios of this gas suggests the material comes from a deep, ancient reservoir. They also use seismic tomography to see how material moves. This helps them understand how subducted oceanic slabs sink into the mantle.