MAJOR-ELEMENT CHEMICAL-DISCRIMINATION OF MAGMA-BATCHES IN LAVAS FROM KILAUEA VOLCANO, HAWAII, 1954 - 1971 ERUPTIONS

Chemical distinction of magma-batches requires methods that account for the stoichiometry of all differentiation processes contributing to the chemical diversity. Intercepts on Pearce element-ratio diagrams that account for the stoichiometry of differentiation processes and ratios of conserved elements discriminate magma-batches within suites of lavas from Kilauea Volcano, Hawaii. These methods can effectively distinguish magma-batches if these are chemical systems closed to some constituents during their evolution. Compositions of material from thirteen historic eruption sequences of Kilauea Volcano between 1954 and 1971 are tested for within-suite and between-suite differences with Pearce element ratios. The within-suite variation, compared to analytical precision, measures whether the samples are from more than one magma-batch. Between-suite differences distinguish magma-batches in a set of eruptive sequences. The 1954-1971 Kilauea eruption sequences comprise a minimum of four magma-batches. The lavas from the Mauna Ulu sequence (erupted 1969-1971) can be shown to comprise more than one magma-batch. The lavas erupted in 1969 along the East Rift Zone (Aloi and Alae Craters) and the Mauna Ulu lavas have the same chemical characteristics, but differ from the lavas of the other eruptive sequences. The Kilauea Iki (1959) lava sequence represents a magma-batch that is chemically different from batches inferred for all the 1954-1971 lava sequences. One magma-batch can account for all other sequences in the period 1954-1968. The temporal and spatial relations of the delineated batches suggest that more than one batch can be in the volcanic edifice at one time and that one batch can simultaneously occupy more than one transport path.