A piece of rock within an igneous mass which is not derived from the original magma but has been introduced from elsewhere, especially the surrounding country rock.
- ‘The granite contains abundant xenoliths of the country rock.’
- ‘However, rare xenoliths of sedimentary rocks occur in the granite.’
- ‘If the magma has risen quickly from the source region of the volcano, the xenoliths may represent country rock from all levels of the crust through which it has travelled.’
- ‘Partial melting models, isotopic studies and the petrology of entrained ultramafic xenoliths suggest that many basanitic magmas are sourced in the asthenosphere.’
- ‘The basalt, inferred to be of Miocene age, appears to be an alkali basalt that contains xenoliths of ultramafic rocks (peridotite and pyroxenite) up to a few centimeters in size.’
We take a look at several popular, though confusing, punctuation marks.