JOHN FOURNELLE
Director, Electron Microprobe Lab Ph.D. 1989, Johns Hopkins University
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Cameca SX50/51
Electron Microprobe
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One of my favorite images is on my card: "Save the Earth
Garden". Find out more about it and
download a 178 KB copy
(This page is somewhat "old"; more up-to-date information about research is at the Electron Microprobe Lab page
Research Interests and Projects
Volcanic eruptions and early peoples of the Alaska Peninsula:
Aleutian Volcanic Action
Akutan Volcano 3/96
198 KB image of Akutan
Photo by U.S.G.S. For more details on active Aleutian volcanoes: Alaska Volcano Observatory
Aleutian arc volcanism:
I have been studying Shishaldin
Volcano,
one of the largest Aleutian volcanic centers, since 1984. Unlike other
Aleutian volcanoes, Shishaldin has erupted a wide range of lavas and
pyroclastics -- 3 types of basalts as well as dacite, with apparently
little andesite. A major question in arc petrology concerns the
significance of high alumina basalts, which generally have abundant
plagioclase phenocrysts, and their relation to high magnesian basalts.
A variety of tools are used, including major and trace element
geochemistry, mineral chemistry, phase equilibria, plus the recently
developed crystal size distribution technique.
Shishaldin page with
photos
Sulfur-rich Volcanic Eruptions
and Magmatic Anhydrite
Some recent volcanic eruptions
have been recognized as having high sulfur contents, which may
have
significant climatic effects. I have been studying anhydrite-bearing
pumices from the 1985 eruption of Nevado del Ruiz (Colombia) and
the
1991 eruption of Mt. Pinatubo. As anhydrite phenocrysts rapidly
dissolve away after several rainy seasons, the presence of such
sulfur-rich eruptions in the geologic record is poorly known. The
discovery of anhydrite inclusions within other phenocrysts (e.g.,
plagioclase, hornblende, or orthopyroxene as shown in this BSE
image),
however, may provide a valuable clue to
discovering past sulfur-rich eruptions. The host minerals for the
inclusions can also provide important clues to the pre-eruption
magmatic conditions (e.g., pressure, temperature and melt water
content).
Magmatic anhydrite page
Courses Taught:
Syllabus, readings and software
Geology 777: Electron Microprobe Analysis This 2-credit course is taught once a year and provides a theoretical background to an understanding and appreciation of the operation of the electron microprobe. Actual hands-on training for running the SX50 is provided at the time that a user requires it.
Syllabus, readings and software
SELECTED PUBLICATIONS
Fournelle J, Carmody R and Daag A (1996) Anhydrite-bearing Pumices from the June 15, 1991 Eruption of Mount Pinatubo: Geochemistry, Mineralogy, and Petrology, in Fire and Mud: Eruiptions and Lahars from Mount Pinatubo, Philippines, Edited by Newhall and Punongbayan, PHIVOLCS-University of Washington, p. 845-863
Fournelle J, Marsh BD and Myers JD (1994) Age, character and significance of Aleutian Arc Volcanism, in Plafker and Berg (ed) Cordilleran Orogen: Alaska (Volume G-1 of The Decade of North American Geology, published by the Geological Society of America).
Fournelle J and Marsh BD (1991) Shishaldin Volcano: Aleutian high-alumina basalts and the plagioclase accumulation question. Geology 19:234-237.
Fournelle J (1990) Anhydrite in Nevado del Ruiz November 1985 pumice: relevance to the sulfur problem. Journal of Volcanology and Geothermal Research 42:189-201.
UW Electron Microprobe Lab
John's Picks to Other Home Pages
A plethora of links to other home pages, selected by yours truly
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