Basaltic magma

Definition

Basaltic magma is a type of molten rock that is low in viscosity and contains a high proportion of iron and magnesium, resulting in its dark color and high temperature. This type of magma is primarily associated with divergent plate boundaries and hotspots, playing a crucial role in forming specific types of volcanoes characterized by their shape and eruption style.

5 Must Know Facts For Your Next Test

1. Basaltic magma typically forms at mid-ocean ridges or hotspots where tectonic plates are pulling apart or where mantle plumes rise.
2. The low viscosity of basaltic magma allows it to travel great distances from the volcanic vent, leading to the formation of broad shield volcanoes like Mauna Loa in Hawaii.
3. Eruptions of basaltic magma are generally non-explosive, characterized by effusive flows rather than violent explosions.
4. Basaltic lava flows can create unique landforms such as lava tubes and extensive sheet flows due to its ability to spread out over large areas.
5. The composition of basaltic magma can vary based on the source material and the depth at which it forms, impacting the minerals present in the resulting rock.

Review Questions

• How does the low viscosity of basaltic magma influence the types of volcanoes formed from it?
  • The low viscosity of basaltic magma allows it to flow easily, which contributes to the formation of shield volcanoes. These volcanoes have broad, gently sloping sides because the lava can travel long distances before cooling and solidifying. In contrast, more viscous magmas tend to create steep-sided stratovolcanoes due to their inability to flow as far, leading to explosive eruptions instead.
• Compare and contrast the eruption styles associated with basaltic magma versus other types of magma.
  • Basaltic magma is primarily associated with effusive eruptions, characterized by the gentle outpouring of lava flows. In contrast, more viscous magmas like andesitic or rhyolitic can lead to explosive eruptions due to their inability to release gas efficiently. This difference in eruption styles significantly affects the landforms created by each type; basaltic eruptions typically build wide shield volcanoes, while explosive eruptions often create steep stratovolcanoes with volcanic ash and pyroclastic materials.
• Evaluate the environmental impact of basaltic lava flows on surrounding ecosystems during an eruption.
  • Basaltic lava flows can significantly alter local ecosystems during an eruption by covering vegetation and altering landscapes. While the immediate effect may be destructive as habitats are buried under lava, over time, these areas can recover and become rich in nutrients as the basalt weathers. This can lead to new growth and increased biodiversity, demonstrating a dynamic interplay between volcanic activity and ecological succession in affected regions.

Related terms

Viscosity: A measure of a fluid's resistance to flow; basaltic magma has low viscosity, allowing it to flow easily and create broad, shield-shaped volcanoes.

Shield Volcano: A type of volcano built up by the flow of low-viscosity basaltic lava, resulting in a wide, gently sloping structure.

Hawaiian Eruptions: Effusive volcanic eruptions characterized by the gentle release of basaltic lava, often producing large amounts of lava fountains and extensive lava flows.