A hypabyssal intrusion refers to a shallow-level igneous intrusion, typically occurring at depths of less than a few kilometers below the Earth’s surface. These intrusions are often associated with dikes, sills, and laccoliths and are important in understanding the processes of magma emplacement and the formation of fine-grained igneous rocks.
Reference: Johannsen, A. (1931). A Descriptive Petrography of the Igneous Rocks. University of Chicago Press.