Igneous Rocks Flashcards
What is the difference between lava and magma
Lava is molten rock that has reached the earth’s surface while magma is molten rock stored in the earths crust
What causes magma to form
Decompression melting and a volatile
Decompression melting
When rock in the mantle starts to move up toward the crust causing a large decrease in pressure which results in the rock partially melting
Volatiles
A substance that evaporates easily and exists as a gas on earth’s surface
What are assimilation and contamination, and how do they differ
The parts of rocks that are taken by magma rise and become magma as well. Assimilation is when large chunks of rock are incorporated into the magma, while contamination is a partial melt of the wall of the magma rise that slowly incorporates.
Where does magma form
convergent boundaries, divergent boundaries, and hot spots
What types of magmas exist
Felsic, intermediate, mafic, and ultramafic
What changed in the different types of magma
Silica content
What six factors control magma composition
Source rock, partial melting, crystal settling, magma mixing, assimilation, and contamination
What generally happens to the composition of magma over time
Becomes more felsic because mafic minerals slowly extract
What affects how fast molten is able to cool
Depth of the magma, size, and shape of the magma body, and presence of groundwater
What are the two different types of igneous rock (one forms on the surface the other form under the surface)
Extrusive and intrusive
What does texture describe in igneous rocks
Crystal size, porosity, and if it’s made up of fragments of volcanic debris
What are the six common textures when talking about igneous rocks
Glassy, aphanitic, phaneritic, porphyritic, pyroclastic, and vesicular
What is an igneous composed of
An igneous rock composition is inherited by the molten rock it came from
What does Bowen’s Reaction Series tell us about the minerals on the table
It identifies at what temperature the minerals in the table crystalize
What does Bowen’s Reaction table tell us about different igneous rocks types
It identifies generally what minerals are found in the different types of igneous rocks
What are the two names for a felsic rock based on where it cooled and which is which
Rhyolite (extrusive) and Granite (intrusive)
What are the two names for an intermediate rock based on where it cooled and which is which
Andesite (extrusive) and diorite (intrusive)
What are the two names for an mafic rock based on where it cooled and which is which
Basalt (extrusive) and Gabbro (intrusive)
What is it called when an ultramafic rock is cooled intrusively
Peridolite
What tends to happen to rocks that cause them to become more and more felsic overtime
Partial melting (more felsic minerals melt first and rise from the more mafic minerals) and crystal settling
What minerals are in felsic rocks? (6)
Orthoclase, Quartz, Plagioclase (Na-rich), Biotite, Muscovite, Amphibole (only a little bit)
What minerals are in intermediate rocks? (5)
Biotite, Amphibole, Plagioclase, Pyroxene (only a little), Quartz (only a little)
What minerals are in mafic rocks? (4)
Plagioclase (Ca-rich), Amphibole, Pyroxene, Olivine
What minerals are in ultramafic rocks? (2)
Pyroxene, Olivine
