Igneous Processes and Volcanoes

Igneous Processes and Volcanoes

• Bowen's Reaction Series: Key relationship between minerals and temperature in igneous rocks. Certain minerals always form together and exclude others, depending on cooling temperature. Bowen's experiments showed this. Mafic minerals crystallize at higher temperatures than felsic minerals.

• Magma Generation: Magma comprises melt, solids, and volatiles. Melt is minerals that liquefied; solids are crystallized minerals in the melt; volatiles include water vapor, carbon dioxide, sulfur, and chlorine. These components influence magma's behavior.

• Geothermal Gradient: Earth's temperature increases with depth. The average geothermal gradient in the upper 100 km of the crust is 25°C per kilometer of depth. The temperature at any depth depends on pressure. Higher pressure increases the melting temperature of rocks.

• Volcanism: Molten rock (lava) reaching Earth's surface. Volcanoes form where lava solidifies. Volcanoes are categorized based on location (interplate or intraplate), type, hazards, and monitoring.

• Interplate Volcanoes: Located at active plate boundaries (mid-ocean ridges, subduction zones, and continental rifts). These include most mid-ocean ridge volcanoes, with basalt being the most common type of rock.

• Intraplate Volcanoes: Located within tectonic plates, away from plate boundaries. Many are associated with hotspots. Hotspots are stationary sources of magma in the mantle.

• Volcano Features and Types: Volcanoes vary in shape, eruption style, and composition. Different types include shield volcanoes, stratovolcanoes, cinder cones, and calderas.

• Volcanic Hazards: Lava flows, pyroclastic flows (hot gas and rock), lahars (volcanic mudflows), landslides, and volcanic gases.

• Volcanic Monitoring: Techniques used to predict eruptions, such as analysis of earthquake activity, gas emissions, and ground deformation.