Contact aureole

Article By:

Speer, J. Alexander Department of Marine, Earth, and Atmospheric Sciences, School of Physical and Mathematical Sciences, North Carolina State University, Raleigh, North Carolina.

Last reviewed:November 2019

DOI:https://doi.org/10.1036/1097-8542.158600

The zone of alteration surrounding a body of igneous rock caused by heat and volatiles given off as the magma crystallized. Changes can be in mineralogy, texture, or elemental and isotopic composition of the original enclosing (country or wall) rocks, and progressively increase closer to the igneous contact. The contact aureole is the shell of metamorphosed or metasomatized rock enveloping the igneous body (Fig. 1). The ideal contact aureole forms locally around a single magma after it is emplaced. Metamorphism over a much larger area can result from coalescing of several contact aureoles. This is termed a contact-regional metamorphic aureole and is thought responsible for the regional metamorphism of several mountain areas. Other contact aureoles develop at greater depths and may be physically emplaced to shallower levels along with the igneous body. These are termed dynamothermal aureoles. See also: Igneous rocks; Magma; Metamorphic rocks; Metamorphism; Metasomatism; Pluton

The content above is only an excerpt.