Small and short-lived magma batches at composite volcanoes: time windows at Tongariro volcano, New Zealand

any are volcanoes are characterized by frequent eruptions of small (<0.1km( 3)) volume. A keg question is do such small events represent discrete magma batches or do these magmas share a partial common history and to what dept hs? The last 1000 years of eruptions at Tongariro volcano, New Zealand, off er a series of time-calibrated 'snap shots' of an are magmatic system. Comp lex and abrupt changes in magma chemistry at Tongariro attest to the small size (<1 km(3)) and short Life span (years to decades) of many magma batche s and a powerful role for shallow level assimilation, fractional crystalliz ation and mingling in modifying magma compositions on time scales as short as a year.