GEOL-1021EL Lecture 10: volcanoes lecture 10
16 Jun 2018
School
Department
Course
Professor
GEOL-1021
November 16th, 2017
Volcanoes
•About Volcanoes
•windows to which we see the interior of the earth
•help us understand the plate tectonic process and mantle convection
•connected to the earth’s hydrosphere and atmosphere
•Volcano: hill or mountain made up of lavas and other erupted materials
•main thing is that its something that can erupt
•As geosystems:
•Parts:
•rocks
•magmas and lavas
•gasses and hydrous fluids
•Eruptions often reflect replenishment of a magma chamber at depth
The grey layers are all previous eruptions!
•Eruptive styles and landforms
•Central eruptions:
•Shield volcanoes (basaltic magmas)
•built by the accumulation of thousands of thing basaltic flows that spread as gently
sloping sheers. magmas can erupt on the flanks of a volcano as well as flow from the
central vent.
•Volcanic domes
•bulbous masses of felsic lava, which are so viscous that instead of flowing, they pile up
over the vent.
•Cinder-cone volcanoes
•formed when ejected material is deposited as layers that dip away from the crater at
the summit. the vent beneath the crater is filled with fragmental debris.
•Monogenetic volcanoes// only erupt once
•Stratovolcanoes (felsic magmas) ((mt fuji))
•built from alternating layers of pyroclastic material and lava flows. lava that has
solidified in fissures form rib like dikes that strengthen the cone
•volcanic craters
•found at the summits of most volcanoes. After an eruption, lava often sinks back into
the vent and solidifies, to be blaster out by a later pyroclastic explosion
•calderas (collapsed volcanic system)
•result when a violent eruption empties a volcano’s magma chamber, which then cannot
support the overlying rock. it collapses, leaving a large steep-walled basin.
•Diatremes (kimberlites)
•cone that is narrow and makes a hole in the planet.
•gasses explode
•Carrot-shaped
•approx. 2 km deep
•Approx. 1 km crater diameter
•3 different facies
•crater facies
•Diatreme facies
•hypabyssal facies
