1. This is especially critical for komatiite lavas and ultramafic intrusive rocks . 2. Igneous intrusive rocks are generally not divided into formations. 3. The intrusive rocks ( late Precambrian ) are in part covered by sand. 4. The mineralogy changes with distance from the intrusive rock . 5. Granodiorite, tonalite and diorite are most common intrusive rocks found in continental arcs. 6. Magmatic fluids coming from the intrusive rock may also take part in the metamorphic reactions. 7. Intrusive rocks formed at greater depths are called plutonic or " abyssal ".8. The intrusive rocks of the area are composed of three types : ring intrusions and central plutons. 9. The quartz-porphyries are distinguished from the rhyolites by being either intrusive rocks or Palaeozoic lavas. 10. Alignment of tabular minerals in metamorphic rocks, igneous rocks and intrusive rocks may form a foliation.
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