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Smithsonian Contributions to the Earth Sciences • Number 12 Serial Publications of the Smithsonian Institution

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Smithsonian Contributions to the Earth Sciences • Number 12 Serial Publications of the Smithsonian Institution GRANT HEIKEN aSa-$T?-x-7-0087) AN ATLAS OFVOLCANIC N74-25882 ASH (Wasa) -5 p HC ~e CSCL 08P Unclas G3/13 40342 SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES • NUMBER 12 SERIAL PUBLICATIONS OF THE SMITHSONIAN INSTITUTION The emphasis upon publications as a means of uuiubing ln ,.w0 dg .... a ...... by the first Secretary of the Smithsonian Institution. In his formal plan for the Insti- tution, Joseph Henry articulated a program that included the following statement: "It is proposed to publish a series of reports, giving an account of the new discoveries in science, and of the changes made from year to year in all branches of knowledge." This keynote of basic research has been adhered to over the years in the issuance of thousands of titles in serial publications under the Smithsonian imprint, com- mencing with Smithsonian Contributions to Knowledge in 1848 and continuing with the following active series: Smithsonian Annals of Flight Smithsonian Contributions to Anthropology Smithsonian Contributions to Astrophysics Smithsonian Contributions to Botany Smithsonian Contributions to the Earth Sciences Smithsonian Contributions to Paleobiology Smithsonian Contributions to Zoology Smithsonian Studies in History and Technology In these series, the Institution publishes original articles and monographs dealing with the research and collections of its several museums and offices and of profes- sional colleagues at other institutions of learning. These papers report newly acquired facts, synoptic interpretations of data, or original theory in specialized fields. These publications are distributed by mailing lists to libraries, laboratories, and other in- terested institutions and specialists throughout the world. Individual copies may be obtained from the Smithsonian Institution Press as long as stocks are available. S. DILLON RIPLEY Secretary Smithsonian Institution -Z SMITHSONIAN CONTRIBUTIONS TO THE EARTH SCIENCES * NUMBER 12 An Atlas of Volcanic Ash Grant Heiken %ON . SMITHSONIAN INSTITUTION PRESS City of Washington 1974 / ABSTRACT Heiken, Grant. An Atlas of Volcanic Ash. Smithsonian Contributions to the Earth Sciences, number 12, 101 pages, 15 figures, 33 plates, 3 tables, 1974.- Volcanic ash samples collected from a variety of recent eruptions were studied, using petrography, chemical analyses, and scanning electron microscopy to characterize each ash type and to relate ash morphology to magma composition and eruption type. The ashes are best placed into two broad genetic categories: magmatic and hydrovolcanic (phreatomagmatic). Ashes from magmatic eruptions are formed when expanding gases in the magma form a froth that loses its coherence as it approaches the ground surface. During hydrovolcanic eruptions, the magma is chilled on contact with ground or surface waters, resulting in violent steam eruptions. Within these two genetic categories, ashes from different magma types can be characterized. The "pigeon hole" classification used here is for convenience; there are eruptions which are driven by both phreatic and mag- matic gases. The morphology of ash particles from magmatic eruptions of high-viscosity magma is governed primarily by vesicle density and shape. The vitric ash par- ticles are generally angular, vesicular pumiceous fragments, or thin vesicle wall fragments. The morphology of lithic fragments is dependent on the texture and mechanical properties of the rock units broken up during the eruption; most of the samples studied contain equant, angular to subrounded lithic fragments. Ash particles from eruptions of low-viscosity magmas are mostly droplets; droplet shape is in part controlled by surface tension, acceleration of the droplets leaving the vent, and air friction. Shapes range from perfect spheres to a variety of twisted, elongate droplets, with smooth, fluidal surfaces. The morphology of ash particles from hydrovolcanic eruptions is controlled by stresses within the chilled magma which result in fragmentation of the glass to form small blocky or pyramidal ash particles. Vesicle density and shape play only a minor role in determining the morphology of these ash particles. OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Smithsonian Year. SI PRESS NUMBER 4983. SERIES COVER DESIGN: Aerial view of Ulawun Volcano, New Britain. Library of Congress Cataloging in Publication Data Heiken, Grant An atlas of volcanic ash. (Smithsonian contributions to the earth sciences, no. 12) 1. Volcanic ash, tuff, etc. I. Title. II. Series: Smithsonian Institution. Smithsonian contribu- tions to the earth sciences, no. 12. QE1.227 no. 12 [QE461] 552'.2 73-13519 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 - Price $2.00 // Contents Page Introduction ............. .................................... 1 Ash Formation ............ .................................... 1 M agm atic Eruptions ............................................ Hydrovolcanic (Phreatomagmatic) Eruptions ....................... 2 Acknowledgments .............................................. 2 M agm atic Eruptions ............................................... Ash of Basaltic Com position ..................................... Pacaya, Guatemala ............ ........................... 3 Fuego, Guatemala ....................................... 3 Cerro N egro, N icaragua ........................................ 3 E tn a, Italy ..................................... 4 Deception Island, Antarctica .................................... 4 Kilauea Iki, H awaii .......................................... 4 Kilauea, H awaii (reticulite) ................................... 5 Aloi-Alae Vent Area, H awaii ................................... 5 Oshima, Japan ............... ....................... 5 T aal, Philippines ........... 5.................................5 Ashlike Particles of Basaltic Composition .......................... 6 M akaopuhi Pele's Hair .................... 6 Flow Top Glass-Kilauea Crater, Hawaii ........................ Ash of Andesitic to Rhyolitic Composition ......................... 7 Ruapehu, N ew Zealand ....................................... 7 M erapi, Indonesia ...... ..................................... 7 Mayon, Philippines ........ .............................. 7 Krakatau, Sunda Straits, Indonesia . ........................... 8 Santiaguito, Guatem ala ........................... 8 K atmai, A laska .................................. 8 Mazama (Crater Lake) Ash .................................... 9 Ash of Carbonatite Composition .................................. 9 Oldoinyo Lengai, Tanzania .................................... 9 Hydrovolcanic (Phreatomagmatic) Eruptions ........................ 9 Ash of Basaltic Composition ......... ............................ 9 Capelinhos, Azore Islands ..................................... 9 Surtsey, Vestmann Islands, Iceland .............................. 10 T aal, Philippines ................................... 10 T able R ock, O regon ............... .......................... 10 Kilauea, H aw aii ........ .................................... 10 Ash of Rhyolitic Com position ................................... 11 Panum Crater, California ..................................... 11 Sugarloaf, San Francisco Mountains, Arizona ................... 11 Ash from Littoral Steam Eruptions ................................. 11 Basaltic Composition .... ...................................... 12 Puu Hou Littoral Cones, Hawaii ............................... 12 iii Page Sand Hills Littoral Cone, Hawaii (historic) ..................... 12 Ash-Size Particles of Meteorite Impact and High-Energy Explosion Origin .......................................... 12 Ries Basin, Germ any ............. .......... ................. 12 Dial-Pack Explosion, Alberta, Canada ................... ....... 13 Conclusions and Summary ................ ....................... 13 Literature Cited ........ ........................................ 13 Appendices ............................. ......................... 15 Appendix I: Chemistry of the Volcanic Ashes Studied for This Report .................................................... 15 Appendix 2: Gas Release Study of Selected Volcanic Ashes (by Everett K. Gibson, Jr.) ........... ...................... 15 iv An Atlas of Volcanic Ash Grant Heiken Introduction ized in the text with percentages of glass, tachylite, crystal fraction, lithic fragments. Morphologic descriptions of volcanic ash par- This is an expanded version of a paper by ticles are present in the literature, mostly as thin- Heiken (1972) on the morphology a petrography section descriptions. Shard shapes are rarely de- of volcanic ash. For a review of the mechanisms scribed as three-dimensional forms; analyses of this of ash formation and introductory text for each sort are generally restricted to bombs and other section of this atlas, see the paper by Heiken; there coarse-grained volcanic ejecta (Wentworth, 1938). is, however, some necessary duplication between Furthermore, only recently, Walker and Croasdale the two papers. ash mor- It is hoped (1972) and Heiken (1972) have related that the reader using this catalog as phology to the composition of the magma or type a reference can, on the basis of petrography and of eruption. ash morphology, infer the genesis of an ash sample. The purpose of this study was to analyze a large This catalog is potentially useful when working variety of volcanic
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