GEOB 103 Chapter Notes - Chapter 11: Volcanic Arc, Shield Volcano, Gabbro

• School: UBC
• Department: Geographical Biogeosciences
• Course: GEOB 103
• Professor: Brett Eaton

Document Summary

Mid-oceanic ridges fig 11. 1 (map&xs: crustal creation (basalt, gabbro) fig. 11. 2, ages @ ridge: shape depends on spreading rate. Volcanic arcs (fig 11. 3 x sec: subduction (introduces h2o, ocean island arc vs. continental arc, melt occurs @ 100 km, +/, cascade volcanic arc: mt. Hot, low silica magma low viscosity (basalt, gabbro) High silica magma high viscosity & gas content (water) (andesite, rhyolite) Result: different magmas produce different volcanoes (fig. 11. 4) (ph 11. 8a) basaltic lava shield volcanoes, large low gradient (ph 11. 6a) (ph 11. 8b) andesite lava strato volcanoes, combine ash layers & flows (ph 11. 6c) Fig 11. 3: convergent margins explosive, eruptive, high relief landforms (ph. Volcanic gasses: co2, so2 (global climate, 1816), h2o. Eruption sizes & types (fig 11. 7): depend on [si], [h2o] Hawaiian as above + cinders (weakly explosive) Strombolian sporadic explosive eruptions (still basaltic magma), scoria cones, common for island arcs (subduction zones) Plinian strato volcanoes, silica-rich magma, mostly landscapes of basaltic volcanism.