Geoscience Reference
In-Depth Information
electron capture
absorption of an electron by a nucleus.
endothermic reaction
chemical reaction that requires heat in order to take place.
epicentre
location of an earthquake specified by latitude and longitude. Full location
including depth is termed the focus or hypocentre.
epicentral distance
distance from the epicentre of an earthquake to some other point on the
Earth's surface, measured along a great circle in degrees or kilometres.
erosion
process by which rock is worn away and the material removed.
extrusion
eruption of magma.
exothermic reaction
chemical reaction that releases heat.
facies
character of a rock; can be applied to the appearance, composition or physical
environment in which the rock originated.
fault
fracture in a rock body, along which motion has occurred or is still occurring.
feldspar
mineral family (XAl)(AlSi)
3
O
8
,where X
=
K, Na, Ca; plagioclase feldspars have
X
=
Na, Ca; alkali feldspars have X
=
Na, K.
fore-arc basin
sedimentary basin on the trench side of the volcanic arc of a subduction zone.
foreland basin
sedimentary basin on the trench side of a continent-continent collision zone.
fractionation
separation of components in a magma (e.g., by precipitation of crystals).
free oscillation
vibration of the whole Earth after a major earthquake.
frequency
number of oscillations per unit time; unit is Hertz (Hz), which equals one cycle
per second.
Ga
10
9
years, giga-annum.
gabbro
coarse-grained intrusive equivalent of basalt; composed of calcic plagioclase,
clinopyroxene, with or without olivine, and/or orthopyroxene.
gamma decay
radioactive decay by emission of a gamma ray or photon (a short-wavelength
electromagnetic wave).
geotherm
temperature-depth curve within the Earth.
gneiss
foliated metamorphic rock rich in quartz and feldspar; can be derived from igneous or
sedimentary rocks.
Gondwanaland
former continent that comprised present-day South America, Africa, India,
Australia and Antarctica; started to break up about 150 Ma ago.
granite
type of plutonic rock with quartz together with plagioclase-feldspar, the plagioclase
making up between 10% and 65% of total feldspar.
granitoid
family of granite-like rocks.
granodiorite
type of plutonic rock with quartz together with plagioclase-feldspar, the
plagioclase making up between 65% and 90% of total feldspar.
