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