GEOL 103 Lecture Notes - Lecture 6: Mantle Plume, Igneous Rock, Continental Crust

• School: College of Charleston
• Department: Geology and Environmental Geosciences
• Course: GEOL 103
• Professor: Hall

Document Summary

Basalt is a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. The difference between basalt and gabbro is that basalt is a fine-grained rock while gabbro is a coarse-grained rock. Most of the basalt found on earth was produced in just three rock-forming environments: Convection currents deliver hot rock from deep in the mantle. This hot rock melts as the divergent boundary pulls apart, and the molten rock erupts onto the sea floor. These submarine fissure eruptions often produce pillow basalts. Small plume of hot rock rises up through the mantle from a hotspot on. Basalt production at these locations begins with an eruption on the ocean floor.