Basaltic magma

Definition

Basaltic magma is a type of low-viscosity molten rock that is rich in iron and magnesium, typically resulting from partial melting of the mantle. It forms primarily at divergent boundaries and hotspots, leading to the creation of basalt rock when it cools. Due to its lower silica content compared to other magmas, basaltic magma can flow more easily, influencing volcanic activity and landform development.

5 Must Know Facts For Your Next Test

1. Basaltic magma typically has a temperature range of about 1000°C to 1200°C (1832°F to 2192°F) when it forms.
2. This type of magma is commonly associated with shield volcanoes, which have gentle slopes and are formed by the accumulation of low-viscosity lava flows.
3. Basaltic magma contains less than 52% silica, which contributes to its fluidity and ability to flow over long distances before solidifying.
4. The eruptions of basaltic magma are generally less explosive than those of more viscous magmas, making them relatively safe for nearby human populations.
5. Basaltic lava is often responsible for creating new oceanic crust at mid-ocean ridges through the process of seafloor spreading.

Review Questions

• How does the composition of basaltic magma influence its behavior during volcanic eruptions?
  • The composition of basaltic magma, characterized by its lower silica content and higher iron and magnesium levels, leads to lower viscosity. This allows it to flow easily and spread over large areas during eruptions. Consequently, basaltic eruptions tend to be less explosive compared to those involving more viscous magmas like rhyolitic magma. The fluid nature of basaltic lava results in the formation of broad shield volcanoes instead of steep stratovolcanoes.
• Discuss the environmental impact of basaltic magma eruptions compared to those from more viscous magmas.
  • Basaltic magma eruptions typically have a lower environmental impact due to their non-explosive nature. They create extensive lava flows that can cover large areas without causing catastrophic destruction. In contrast, eruptions from more viscous magmas can result in explosive events that emit ash clouds and pyroclastic flows, which pose greater risks to nearby ecosystems and human populations. The gradual formation of new land from basaltic lava can also create habitats for colonization by plants and animals.
• Evaluate the role of basaltic magma in shaping the geological features of the Earth’s crust, especially at divergent boundaries.
  • Basaltic magma plays a crucial role in shaping the geological features of the Earth's crust, particularly at divergent boundaries where tectonic plates move apart. When basaltic magma rises to fill the gap between these plates, it cools and solidifies, forming new oceanic crust through processes like seafloor spreading. This continuous creation of new crust not only contributes to the formation of mid-ocean ridges but also influences global tectonics and ocean circulation patterns. The balance between volcanic activity and plate tectonics driven by basaltic magma is essential for maintaining the dynamic nature of our planet’s surface.

Related terms

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

Rhyolitic magma: Rhyolitic magma is a type of magma that has a higher silica content than basaltic magma, resulting in greater viscosity and typically more explosive volcanic eruptions.

Volcanism:

Volcanism refers to the processes by which magma rises to the Earth's surface and erupts, forming volcanic features and affecting the planet's geology.