A subvolcanic rock, also known as a hypabyssal rock, is an intrusive igneous rock that is emplaced at medium to shallow depths within the crust, and has intermediate grain size and often porphyritic texture between that of volcanic and plutonic rocks. Subvolcanic rocks include diabase (also known as dolerite) and porphyry. Common examples of subvolcanic rocks are diabase, quartz-dolerite, micro-granite and diorite.
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Subvolcanic rock Wikipedia(Text) CC BY-SA