The butterfly counts not months but moments, and has time enough. Rabindranath Tagore
Idea Transcript
Journal of Volcanology and Geothermal Research, 17 (1983) 31--63
31
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
~CWANI.qUR OF ~ O L O A N I C PTROCLA~T FOHNATION: GRAIN-SIZE, SCANNING ELECTRDNM[CRDGCOPY, AND EL"ERIRENTAL STUDIES
KENNETH H. WOHLETZ Earth and Space Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (U.S.A.) (Received September 15, 1982; revised and accepted December 20, 1982) ABSTRACT Wohletz, K.H., 1983. Mechanisms of hydrovolcanic pyroclast formation: grainsize, scanning electron microscopy, and experimental studies. In: M. F. Sheridan and F. Barberi (Editors), Explosive Volcanism. J. Volcanol. Geotherm. Res., 17: 31-63. Pyroclasts produced by explosive magma/water interactions are of various sizes and shapes. Data from analysis of over 200 samples of hydrovolcanic ash are interpreted by comparison with experimentally produced ash. Grain size and scanning electron microscopy (S~) reveal information on the formation of hydrovolcanic pyroclasts. Strombolian explosions result from limited water interaction with magma and the pyroclasts produced are dominant3~v centimetersized. With increasing water interaction, hydrovolcanism increases in explosivity to Surtseyan and Vulcanian activity. These eruptions produce millimeter- to micron-sized pyroclasts. The abundance of fine ash (