GISP2 (continued)

previous page

Volcanic glassOne method for dating the core is tephrochronolog, that is, locating fallout from known volcanic eruptions.

. Electrical conductivity measurements are made along the entire length of the core. Increases in celectrical onductivity indicate the presence of volcanic eruption fallout. Sections of the ice are melted and filtered through a capillary-pore membrane filter. An automated scanning electron microscope equipped for x-ray microanalysis is used to determine the size, shape and elemental composition of hundreds of particles on the filter

Cluster analysis, a multivariate statistical routine, of the elemental compositions of sodium, magnesium, aluminum, silicon, potassium, calcium, titanium and iron is done to identify the volcanic glass particles in the sample. Representative glass particles are re-located for photomicrography and more detailed chemical analysis.

Tephra collected from near the volcanic eruption that may have produced the fallout in the core is ground to a fine powder, dispersed in liquid and filtered through a capillary-pore membrane. Automated SEM analysis is used on the tephra sample to obtain representative elemental composition for the volcanic glass for compariuson with the glass particles found in the ice core. Fallout from several know volcanic eruptions have been found in Greenland.

Selected Bibliography
 Zdanowicz, C. M., Zielinski, G.A. and M. S. Germani, Mount Mazama eruption: Calendrical age verified and atmospheric impact assessed, Geology, 27(7), 621-624, 1999.
 Zielinski, G. A. and M. S. Germani, New ice-core evidence challenges the 1620s BC age for the Santorini (Minoan) eruption, J. Archaeological Sci., 25, 279 - 289, 1998.
 Zielinski, G. A., Dibb, J. E., Yang, Q., Mayewski P. A., Germani, M. S., Whitlow, S. and M. S. Twickler, Assessment of the record of the 1982 El Chichon eruption as preserved in Greenland snow, J. Geophys. Res. 102(D25), 30045 - 26640, 1997.
 Zielinski, G. A., Mayewski, P. A., Meeker, L. D., Gronvold, K., Germani, M. S., Whitlow, S., Twickler, M. S. and K. Taylor, Volcanic aerosol records and tephrochronology of the Summit, Greenland, ice cores, J. Geophys. Res. 102(C12), 26625 - 26640, 1996.
 Zielinski, G. A., Germani, M. S., Larsen, G., Baillie, M. G. L., Whitlow, S., Twickler, M. S., and K. Taylor, Evidence of the Eldgja (Iceland) eruption in the GISP2 Greenland ice core: relationship to eruption processes and climatic conditions in the tenth century, The Holocene 5(2), 129-140, 1995.
 Fiacco, R. J., Thordarson, T., Germani, M. S., Self, S., Palais, J. M., Whitlow, S. and P. Grootes, Atmospheric loading and transport due to 1783/1784 Laki eruption interpreted from ash particles and acidity in the GISP2 ice core, Quaternary Research 42(3), 231-240, 1994.
 Zielinski, G. A., Fiacco, R. J., Mayewski, P. A., Meeker, L. D., Whitlow, S., Twickler, M. S., Germani, M. S., Endo, E. and M. Yasui, Climatic impact of the AD 1783 Asama (Japan) eruption was minimal: Evidence from the GISP2 ice core, Geophysical Research Letters 21(22), 2365-2368, 1994.
 Fiacco, R. J., Palais, J. M., Germani, M. S., Zielinski, G. A. and P. A. Mayewski, Characteristics and possible source of 1479 AD volcanic ash layer in a Greenland ice core, Quaternary Research 39, 267-273, 1993.

top of page