Flux melting

Definition

Flux melting is a geological process that occurs when the addition of volatile components, like water or carbon dioxide, lowers the melting point of rocks, allowing them to melt at lower temperatures than they normally would. This process is crucial in generating magma in subduction zones, where oceanic plates descend into the mantle and introduce these volatiles into the surrounding mantle rock. By altering the physical conditions under which melting occurs, flux melting plays a key role in the formation of different types of magma and ultimately influences volcanic activity.

5 Must Know Facts For Your Next Test

1. Flux melting typically occurs in subduction zones where oceanic crust is forced down into the mantle, releasing water and other volatiles.
2. The presence of water lowers the melting temperature of mantle rocks from around 1300°C to approximately 800°C, significantly influencing magma generation.
3. This process leads to the formation of basaltic and andesitic magmas, which are often associated with explosive volcanic eruptions.
4. In addition to subduction zones, flux melting can occur at mid-ocean ridges and hotspots, though it is less common in those settings.
5. Understanding flux melting is essential for predicting volcanic eruptions and assessing volcanic hazards in regions near subduction zones.

Review Questions

• How does the addition of volatiles during flux melting affect the composition and behavior of generated magma?
  • The addition of volatiles like water significantly reduces the melting point of rocks, allowing them to melt at lower temperatures. This results in the production of magma that is richer in certain elements, which affects its composition. The presence of volatiles also influences the viscosity of the magma, making it more likely to erupt explosively due to the buildup of gas pressure.
• Discuss the role of subduction zones in facilitating flux melting and how this process impacts volcanic activity.
  • Subduction zones play a critical role in flux melting by enabling oceanic plates to descend into the mantle. As these plates sink, they release volatiles such as water into the surrounding mantle rock. This leads to melting at lower temperatures, creating magma that rises to form volcanoes. The nature of this volcanic activity can vary greatly depending on the specific characteristics of the melted material and its volatile content.
• Evaluate how understanding flux melting contributes to our overall knowledge of volcanic hazards associated with subduction zones.
  • Understanding flux melting enhances our knowledge of volcanic hazards by revealing how magma is generated under specific tectonic settings like subduction zones. By studying this process, scientists can better predict which volcanoes are likely to erupt and what type of eruptions may occur. This information is crucial for hazard assessment and disaster preparedness in regions prone to volcanic activity, as it allows for more accurate forecasting based on geological conditions.

Related terms

Subduction Zone:

A tectonic boundary where one plate moves under another, leading to significant geological activity including magma generation and volcanic eruptions.

Magma: A molten rock mixture found beneath the Earth's surface, which can solidify to form igneous rock when cooled.

Volatiles:

Substances that can easily become gas at relatively low temperatures and pressures, such as water vapor and carbon dioxide, which are crucial for flux melting.