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Identification of Dacitic Tephra by Activation Analysis of their Primary Mineral Phenocrysts1

Published online by Cambridge University Press:  20 January 2017

M.J. Dudas ,
M.E. Harward  and
R.A. Schmitt
M.J. Dudas
Affiliation:
Department of Soil Science, Oregon State University, Corvallis
M.E. Harward
Affiliation:
Department of Soil Science, Oregon State University, Corvallis
R.A. Schmitt
Affiliation:
Department of Chemistry and the Radiation Center, Oregon State University, Corvallis, Oregon 97331 USA
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Abstract

Primary mineral phenocrysts from eight different late Quaternary pyroclastic deposits were fractionated for neutron-activation analysis with the purpose of characterizing each of the deposits on the basis of trace and minor element compositions. In hornblende separates, contents of several rare earth and transition elements were found to be distinctive for the Mazama, Glacier Peak, and several St. Helens deposits. In magnetites, abundances of transition elements are characteristic and serve as good discriminants for the pyroclastic deposits examined in this investigation. Contents of transition and rare earth elements in hyperthenes also appear useful in distinguishing volcanic ash deposits. Trace and minor element abundances in plagioclase phenocrysts did not appear adequate for identification of pyroclastics due to elemental depletion and similarity of contents for feldspar separates. It was found that contents of Sm and Yb in hornblende phenocrysts would serve to distinguish between several pyroclastic deposits from the Pacific Northwest.

Type
Original Articles
Information
Quaternary Research , Volume 3 , Issue 2 , August 1973 , pp. 307 - 315
Copyright
University of Washington

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References

Berlin, R., Henderson, C.M.B., (1969). The distribution of Sr and Ba between the alkali feldspar, plagioclase and groundmass phases of porphyritic trachytes and phonolites. Geochimica et Cosmochimica Acta 33, 247–255.Google Scholar
Borchardt, G.A., Harward, M.E., Schmitt, R.A., (1971a). Correlation of volcanic ash deposits by activation analysis of glass separates. Quaternary Research 1, 247–260.Google Scholar
Borchardt, G.A., Harward, M.E., (1971b). Trace element correlation of volcanic ash soils. Soil Science Society America Proceedings 35, 626–631.Google Scholar
Czamanske, G.K., Porter, S.C., (1965). Titanium dioxide in pyroclastic layers from volcanoes in the Cascade Range. Science 150, 1022–1025.Google Scholar
Dudas, M.J., Schmitt, R.A., Harward, M.E., (1971). Trace element partitioning between volcanic plagioclase and dacitic pyroclastic matrix. Earth and Planetary Science Letters 11, 440–446.Google Scholar
Gast, P.W., (1968). Trace element fractionation and the origin of tholeiitic and alkaline magma types. Geochimica et Cosmochimica Acta 32, 1057–1086.Google Scholar
Gordon, G.E., Randle, K., Goles, G.G., Corliss, J.B., Beeson, M.H., Oxley, S.S., (1968). Instrumental activation analysis of standard rocks with high-resolution gamma-ray detectors. Geochimica et Cosmochimica Acta 32, 369–396.Google Scholar
Kohn, B.P., (1970). Identification of New Zealand tephra-layers by emission spectrographic analysis of their titanomagnetites. Lithos 3, 361–368.Google Scholar
Mullineaux, D.R., Hyde, J.H., Rubin, M., (1972). Preliminary assessment of upper Pleistocene and Holocene pumiceous tephra from Mount St. Helens, southern Washington. Geological Society of America Abstracts with Programs 4, 204–205.Google Scholar
Nagasawa, H., Schnetzler, C.C., (1971). Partitioning of rare earth, alkaline earth elements between phenocrysts and acidic igneous magma. Geochimica et Cosmochimica Acta 35, 953–968.Google Scholar
Osborn, T.W., Dudas, M.J., Schmitt, R.A., (1972). Trace-element variation of individual plagioclase and hornblende phenocrysts. Chemical Geology 10, 205–210.Google Scholar
Philpotts, J.A., Schnetzler, C.C., (1970). Phenocryst-matrix partition coefficients for K, Rb, Sr and Ba with application to anaorthosite and basalt genesis. Geochimica et Cosmochimica Acta 34, 307–322.Google Scholar
Powers, H.A., Wilcox, R.E., (1964). Volcanic ash from Mount Mazama (Crater Lake) and from Glacier Peak. Science 144, 1334–1336.Google Scholar
Randle, K., Gordon, G.G., Kittleman, L.R., (1971). Geochemical and petrological characterization of ash samples from Cascade Range volcanoes. Quaternary Research 1, 261–282.Google Scholar
Schmitt, R.A., Linn, T.A., Wakita, H., (1970). The determination of fourteen common clements in rocks via sequential instrumental activation analysis. Radiochimica Acta 13, 200–212.Google Scholar
Smith, D.G.W., Westgate, J.A., (1969). Electron probe technique for characterizing pyroclastic deposits. Earth and Planetary Science Letters 5, 313–319.Google Scholar
Taylor, S.R., (1965). The application of trace element data to problems in petrology. Ahrens, L.H., Press, F., Runcorn, S.K., Urey, H.C., Physics and Chemistry of the Earth vol. 6, Pergamon Press New York 133–213.Google Scholar
Theisen, A.A., Borchardt, G.A., Harward, M.E., Schmitt, R.A., (1968). Neutron activation for distinguishing Cascade Range pyroclastics. Science 161, 1009–1011.Google Scholar
Wilcox, R.E., (1965). Volcanic ash chronology. Wright, H.E., Frey, D.G., The Quaternary of the United States: Review Volume for the Seventh Congress of the International Association for Quaternary Research Princeton University Press Princeton, N.J 807–816.Google Scholar
Williams, H., (1942). The Geology of Crater Lake National Park, Oregon. Carnegie Institute of Washington, Publication No. 540 162Washington, D.C.Google Scholar