volcanic field polygenetic volcanic field A volcanic field of scattered volcanic vents. These volcanic fields, containing numerous polygenetic volcanoes, are noted for having more than one eruptive event from the same vent(s), rather than the more common monogenetic volcanic field. Polygenetic volcanic fields generally occur where there is a high-level magma chamber. These volcanic fields may show lithological discontinuities due to major changes in magma chemistry, volcanotectonic events, or long erosional intervals, and may last >10 million year period. ENVO ENVO:00000462 Wikipedia:Polygenetic_volcanic_field