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Oxygen Isotope Evidence for Chemical Interaction of Ki lauea Historical Magmas with Basement Rocks |
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| Authors: | Garcia Michael O; Ito Emi; Eiler John M |
| Institution: | 1Department of Geology & Geophysics, University of Hawai’i, Honolulu, HI 96822, USA 2Department of Geology & Geophysics, University of Minnesota, Minneapolis, MN 55455, USA 3Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA |
| Abstract: | K lauea historical summit lavas have a wide range in matrix  18OVSMOWvalues (4·9–5·6 ) with lower values in rockserupted following a major summit collapse or eruptive hiatus.In contrast, 18O values for olivines in most of these lavasare nearly constant (5·1 ± 0·1). The disequilibriumbetween matrix and olivine 18O values in many samples indicatesthat the lower matrix values were acquired by the magma afterolivine growth, probably just before or during eruption. BothMauna Loa and Klauea basement rocks are the likely sources ofthe contamination, based on O, Pb and Sr isotope data. However,the extent of crustal contamination of Klauea historical magmasis probably minor (< 12%, depending on the assumed contaminant)and it is superimposed on a longer-term, cyclic geochemicalvariation that reflects source heterogeneity. Klauea's heterogeneoussource, which is well represented by the historical summit lavas,probably has magma 18O values within the normal mid-ocean ridgebasalt mantle range (5·4–5·8) based on thenew olivine 18O values. KEY WORDS: Hawaii; Klauea; basalt; oxygen isotopes; crustal contamination |
| Keywords: | : Hawaii K |
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