Chapter 04 Vocab Flashcards
Assimilation
The process of magma contamination in which blocks of wall rock fall into a magma chamber and dissolve.
Batholith
A vast composite, intrusive, igneous rock body up to several hundred km long and 100 km wide, formed by the intrusion of numerous plutons in the same region.
Bowen’s Reaction Series
The sequence in which different silicate minerals crystallize during the progressive cooling of a melt.
Dike
A tabular (wall-shaped) intrusion of rock that cuts across the layering of country rock.
Extrusive Igneous Rock
Rock that forms by the freezing of lava above ground, after it flows or explodes out (extrudes) onto the surface and comes into contact with the atmosphere or ocean.
Flood Basalt
Vast sheets of basalt that spread from a volcanic vent over an extensive surface of land; they may form where a rift develops above a continental hot spot, and where lava is particularly hot and has low viscosity.
Fractional Crystallization
The process by which a magma becomes progressively more silicic as it cools, because early-formed crystals settle out.
Geotherm
The change in temperature with depth in the Earth.
Glassy Igneous Rock
Igneous rock consisting entirely of glass, or of tiny crystals surrounded by a glass matrix.
Hot-Spot Volcano
An isolated volcano not caused by movement at a plate boundary, but rather by the melting of a mantle plume.
Igneous Rock
Rock that forms when hot molten rock (magma or lava) cools and freezes solid.
Intrusive Igneous Rock
Rock formed by the freezing of magma underground.
Large Igneous Province (LIP)
A region in which huge volumes of lava and/or ash erupted over a relatively short interval of geologic time.
Lava
Molten rock that has flowed out onto the Earth’s surface.
Lava Flow
Sheets or mounds of lava that flow onto the ground surface or sea floor in molten form and then solidify.
Liquidus
The lowest temperature at which all the components of a material have melted and transformed into liquid.
Magma
Molten rock beneath the Earth’s surface.
Magma Chamber
A space below ground filled with magma.
Obsidian
An igneous rock consisting of a solid mass of volcanic glass.
Partial Melting
The melting in a rock of the minerals with the lowest melting temperatures, while other minerals remain solid.
Pegmatite
A coarse-grained igneous rock containing crystals of up to tens of centimeters across and occurring in dike- shaped intrusions.
Pillow Basalt
Glass-encrusted basalt blobs that form when magma extrudes on the sea floor and cools very quickly.
Pluton
An irregular or blob-shaped intrusion; can range in size from tens of m across to tens of km across.
Pumice
A glassy igneous rock that forms from felsic frothy lava and contains abundant (over 50%) pore space.
Pyroclastic rock
Rock made from fragments that were blown out of a volcano during an explosion and were then packed or welded together.
Scoria
A glassy, mafic, igneous rock containing abundant air-filled holes.
Sill
A nearly horizontal tabletop-shaped tabular intrusion that occurs between the layers of country rock.
Solidus
The highest temperature at which all the components of a material are solid; at the solidus temperature, the material begins to melt.
Stoping
A process by which magma intrudes; blocks of wall rock break off and then sink into the magma.
Superplume
A huge mantle plume.
Tuff
A pyroclastic igneous rock composed of volcanic ash and fragmented pumice, formed when accumulations of the debris cement together.
Ultramafic Rock
An igneous rocks that is rich in iron and magnesium and very poor in silica.
Vesicles
Open holes in igneous rock formed by the preservation of bubbles in magma as the magma cools into solid rock.
Viscosity
The resistance of material to flow.
Volcanic Arc
A curving chain of active volcanoes formed adjacent to a convergent plate boundary.
Volcanic Ash
Tiny glass shards formed when a fine spray of exploded lava freezes instantly upon contact with the atmosphere.
Volcano
(1) A vent from which melt from inside the Earth spews out onto the planet’s surface; (2) a mountain formed by the accumulation of extrusive volcanic rock.
Xenolith
A relict of wall rock surrounded by intrusive rock when the intrusive rock freezes.
