Case studies on the origin of basalt: III. Petrogenesis of the Mauna Ulu eruption, Kilauea, 1969?1971

摘要: During the Mauna Ulu flank eruption on Kilauea, Hawaii, concentrations in lavas of minor elements K, P, Na and Ti, incompatible trace (analyzed by isotope dilution) Rb, Cs, Ba, Sr, REE (except Yb) decreased monotonically linearly with time (or date) eruption. At same time, major Yb, ratios K/Rb, K/Cs, Ba/Rb, 87Sr/86Sr 143Nd/144Nd remained constant. Most scatter raw concentration data is removed a simple correction for olivine (plus chromite) fractionation previously established Wright et al. (1975). These results are explained equilibrium partial melting uniform source. The degree increased about 20% initial value during course element inverted method originated Minster Allegre (1978) simplified Hofmann Feigenson (1983). source has following isotope) ratios: K/Rb=501±7, Ba/Rb=14.0±0.5, Rb/Cs=95±7, Rb/Sr=0.0193 (+0.0045, −0.0090), (Ce/Ba)CN= 1.1±0.1, (Sr/Ba)CN=1.19 (+0.30, −0.19), 87Sr/86Sr=0.703521±0.000016, 143Nd/144Nd=0.512966±0.000008. pattern nearly flat or slightly negative slope (=relative LREE enrichment) between Ce Dy strongly positive Yb. However, this relative HREE enrichment poorly constrained analytical data, highly model dependent may not be true feature. Yb particularly because it essentially constant melts. On other hand, special feature demonstrates that must buffered mineral phase high partition coefficient namely garnet. calculated clinopyroxene/garnet ratio roughly equal to one. In contrast, Kohala volcano had been found contain little no