This study attempts to determine the nature and source of the volatiles emitted during the 1963 eruption of Gunung Agung, utilizing the petrologic method of estimation of volatile release, as well as careful examination of the petrography and chemistry of the 1963 juvenile magmatic eruption products. The 1963 eruption of Gunung Agung produced 0.95 km (super 3) dense rock equivalent (DRE) of basaltic andesite tephra and lava, of which about 0.65 km (super 3) of juvenile tephra may have contributed to the estimated (from atmospheric loading) 7X10 (super 12) g of SO (sub 2) injected into the stratosphere. Application of the petrologic method yields an estimate of 5X10 (super 12) g each of SO (sub 2) and HCl released during the eruption. The 2X10 (super 12) g difference between the two independent estimates of SO (sub 2) released can be most simply accounted for by degassing of about 0.25 km (super 3) DRE of unerupted magma containing a similar pre-eruption S concentration. Glass inclusions, analyzed by electron microprobe, contain an average of 660 ppm S and 3150 ppm Cl, as compared to 90 ppm and 2190 ppm, respectively, in the matrix glass. Maximum S and CI contents of glass inclusions are 1790 and 5330 ppm, respectively. The presence of resorbed hornblende in some samples suggests a pre-eruption, water-rich vapor phase which may have carried S and Cl. Strong evidence for magma mixing presented here suggests a possible basaltic source for some of the S and Cl emitted in the eruption. Comparison of this study, in which the petrologic method yielded a reasonable minimum estimate of SO (sub 2) emissions, with studies of high-S-release eruptions for which the petrologic method failed (El Chichon, Pinatubo), suggests that vapor bubbles within glass inclusions may play an important role in petrologic estimates. Another, unrelated petrologic and geochemical study I completed at the University of Hawaii is included in Appendix B. Central Pacific mid-ocean ridge basalts (MORB) collected by the Ocean Drilling Program near Hawaii, may be representative of the oceanic basement on which the Hawaiian islands were built. Basalts exhibiting only slight, low-temperature, seawater alteration were analyzed for major element, trace element, and isotopic composition. They are characterized by enrichment in the high field strength elements relative to normal MORB (N-MORB), by a distinct positive Eu anomaly, and by Ba/Nb and La/Nb ratios that are much lower than those of other crustal or mantle-derived rocks, but their isotope ratios are similar to those of present-day N-MORB from the East Pacific Rise. petrographic and trace-element evidence indicates that the Eu anomaly was the result of neither plagioclase assimilation nor seawater alteration, and that the enrichments in Eu, Ta, Nb, and possibly U and K relative to N-MORB apparently are characteristic of the mantle source. Age-corrected Nd and Sr isotopic ratios indicate that the source for the lavas recovered at ODP Site 843 was similar to the source for Southeast Pacific MORB. An enriched component within the Cretaceous mantle source of these basalts is suggested by their initial (super 208) Pb/ (super 204) Pb- (super 206) Pb/ (super 204) Pb and epsilon (sub Nd) - (super 206P) b/ (super 204) Pb ratios. The Sr-Pb isotopic trend of Hawaiian post-shield and post-erosional lavas cannot be explained by assimilation of oceanic crust with the isotopic composition of the Site 843 basalts;

West: 115.2800 East: 115.2800 North: -8.2000 South: -8.2000

West: NaN East: NaN North: NaN South: NaN

Provider: SEDIS Publication Catalogue

Data set link: http://sedis.iodp.org/pub-catalogue/index.php?id=1996-044043 (c.f. for more detailed metadata)

This metadata in ISO19139 XML format