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Science 26 July 1996:
Vol. 273. no. 5274, pp. 490 - 493
DOI: 10.1126/science.273.5274.490
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Reports

Volatiles from the 1994 Eruptions of Rabaul: Understanding Large Caldera Systems

Kurt Roggensack, * Stanley N. Williams, Stephen J. Schaefer, dagger Roderic A. Parnell Jr.

The 1994 eruption of Rabaul, in Papua New Guinea, involved a small plinian eruption at Vulcan and a vulcanian eruption on the opposite side of the caldera at Tavurvur. Vulcan's ash leachates indicate seawater interaction that is consistent with earlier observations of low sulfur dioxide emissions and the presence of ice crystals in the initial plinian eruption cloud. In contrast, Tavurvur ash leachates indicate no seawater interaction, and later sulfur dioxide emissions remained high despite low-level eruptive activity. Silicic melt inclusions indicate that the andesitic melt contained about 2 weight percent water and negligible carbon dioxide. Mafic melt inclusions in Tavurvur ash have water and carbon dioxide contents that vary systematically over the course of the eruption. The mafic melt inclusions suggest that a mafic dike intruded from below the silicic chamber and provide further evidence that mafic intrusions drive caldera unrest.

K. Roggensack, S. N. Williams, S. J. Schaefer, Department of Geology, Box 871404, Arizona State University, Tempe, AZ 85287-1404, USA.
R. A. Parnell Jr., Department of Geology, Northern Arizona University, Flagstaff, AZ 86011, USA.
*   To whom correspondence should be addressed.

dagger    Present address: University Space Research Association, NASA/Goddard Space Flight Center, Code 921, Greenbelt, MD 20771, USA.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Are Arc Basalts Dry, Wet, or Both? Evidence from the Sumisu Caldera Volcano, Izu-Bonin Arc, Japan.
Y. TAMURA, K. TANI, O. ISHIZUKA, Q. CHANG, H. SHUKUNO, and R. S. FISKE (2005)
J. Petrology 46, 1769-1803
   Abstract »    Full Text »    PDF »
The subduction factory: its role in the evolution of the Earth's crust and mantle.
Y. Tatsumi and T. Kogiso (2003)
Geological Society, London, Special Publications 219, 55-80
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