Glossary - The Solid Earth - page 659

intrusive rock igneous rock that solidified within the Earth.

ion atom that is not electrically neutral; an atom with fewer than the normal number of
electrons is a positive ion; an atom with more than the normal number of electrons is a
negative ion.

island arc chain of islands above a subduction zone (e.g., Japan, Aleutians).

isostasy the way in which the lithosphere 'floats' on the asthenosphere.

isotherm line or surface of constant temperature.

isotopes forms of an element with differing numbers of neutrons in their nucleus. For
hydrogen, for example, the nucleus of hydrogen, 1 H, consists of one proton; the nucleus of the
hydrogen isotope deuterium, 2 H, consists of one proton and one neutron; the nucleus of
tritium, 3 H, has one proton and two neutrons.

kbar kilobar, 0.1 GPa of pressure.

kerogen organic material that can be transformed into oil and gas.

kimberlite type of peridotite that erupts from great depth in a so-called pipe and occasionally
contains diamonds.

kinematic viscosity dynamic viscosity of a fluid divided by its density; unity of kinematic
viscosity, m 2 s − l ; symbol, ν .

kinetic energy energy that something has by virtue of its motion.

komatiite highly magnesian lava.

large-ion lithophile (LIL) elements elements such as Rb, K, Ba, Th, Sr that have large

ionic radii.

latent heat or heat of fusion the amount of heat which must be supplied to a unit quantity of
agiven solid material at its melting point to change it into a liquid; conversely, the (same)
amount of heat released when a unit quantity of the given liquid material at its melting
temperature is changed into a solid.

latitude angular distance north or south of the equator of a point on the Earth's surface.

Laurasia former continent that comprised present-day North America, Greenland, Europe
and part of Asia; broke up during the Cretaceous, about 90 Ma ago.

lava molten rock when it is erupted at the Earth's surface.

left-lateral fault, sinistral fault fault on which the displacement is such that, to an observer
on the ground, the opposite side is displaced to the left.

lherzolite peridotite composed of olivine, clinopyroxene and orthopyroxene.

liquidus surface in temperature-pressure space above which the system is totally liquid.

lithology physical character of rocks.

lithophile element element usually found in silicate minerals.