Partial melting

Definition

Partial melting is the process by which only a portion of a solid material melts, resulting in a liquid phase that can separate from the solid residue. This process is crucial in understanding the formation of different types of magmas and can lead to the creation of various intrusive igneous features, as well as affecting magma composition and properties.

5 Must Know Facts For Your Next Test

1. Partial melting commonly occurs in subduction zones where water is introduced into the mantle, lowering the melting point of rocks.
2. The extent of partial melting can influence the overall composition of the resulting magma, leading to variations in volcanic rock types.
3. Different minerals have different melting points, so partial melting can result in a liquid that is richer in silica compared to the original rock.
4. The process of partial melting plays a key role in the generation of intermediate magmas, which have characteristics between basaltic and granitic compositions.
5. Partial melting can also contribute to the formation of ore deposits as certain metals may preferentially concentrate in the molten phase.

Review Questions

• How does partial melting influence the formation and characteristics of magmas?
  • Partial melting influences magma formation by determining its composition based on which minerals melt and to what extent. As different minerals have varying melting points, only certain components may transition into the liquid phase while others remain solid. This selective melting affects the chemical properties of the magma, leading to different volcanic rock types based on how much partial melting occurred and which minerals were involved.
• Discuss the role of partial melting in the creation of intrusive igneous features like plutons.
  • Partial melting plays a vital role in forming intrusive igneous features such as plutons. When magma generated by partial melting rises into cooler regions of the crust, it can accumulate and solidify slowly, forming large bodies known as plutons. The composition of these plutons will reflect the minerals that underwent partial melting, often resulting in a variety of rock types depending on their location and the original source material.
• Evaluate how partial melting can lead to economic benefits through ore deposit formation.
  • Partial melting can lead to economic benefits by concentrating valuable metals in molten phases during the process. As certain elements preferentially dissolve into the melt during partial melting, they can become concentrated in specific areas. When this molten material later cools and solidifies, it may form economically significant ore deposits, providing resources such as copper, gold, or other metals that are critical for various industries.

Related terms

Magma: Magma is a molten rock material beneath the Earth's surface, composed of liquid rock, crystals, and dissolved gases.

Pluton: A pluton is a large, intrusive igneous body that forms when magma cools and solidifies below the Earth's surface.

Fractional crystallization: Fractional crystallization is the process by which different minerals crystallize from cooling magma at different temperatures, altering the composition of the remaining liquid.