12847 – Stable Isotopic Study of Sulfur Degassing during the Eruption of Mt. Mazama

Investigator’s Annual Reports (IAR’s) for Crater Lake National Park

Stable Isotopic Study of Sulfur Degassing during the Climactic and Pre-Climactic Eruption of Mt. Mazama, Crate Lake, Oregon


Report Number: 12847

Reporting Year: 1999

Permit Number: CRLA199902-006

Current Status: Checked in

Date Received: Jan 01, 2000

Principal Investigator: Charles W. Mandeville, Department of Planetary Sciences, American Museum of Natural History, New York, NY

Additional investigator(s): Dr. Charles R. Bacon, Dr. James D. Webster

Park-assigned Study Id. # CRLA199902-006

Permit Expiration Date: Jan 01, 2000

Permit Start Date: Jan 01, 2000

Study Starting Date: Jan 01, 1999

Study Ending Date: Jan 01, 2000

Study Status: Completed

Activity Type: Research

Subject/Discipline: Geothermal / Volcanology

Objectives: 1. 20-25 rock samples from Cleetwood pumice fall, Llao Rock pumice fall and Climactic pumice fall and ignimbrite. Total not to exceed 25 specimens (20-40 grams each).;2. 1-2 Crater Lake water samples (1-2 liter volume).

Findings and Status:  As of 12/16/99 we have entered into the second year of our study of sulfur degassing during the climactic and Pre-Climactic Eruption of Mt. Mazama. Bulk sulfur extraction via KIBA reagent was completed on 24 samples of Climactic rock samples during the period of 7/19-23/99. Sulfur concentrations in these samples range from 39 ppm to 244ppm. Extracted sulfur from these samples is presently in the form of silver sulfide Ag2S) and will be analyzed for its isotopic composition(34S/32S) by MILES laser probe in collaboration with Dr. Bruce Taylor of the Geological Survey of Canada during 2/00. Twenty rock samples from Mt. Mazama were collected during our first field season in CRLA NP during 9/13-22/99. Three water samples were taken at Vidae Falls, Cleetwood Cove, and a deep water sample was collected in collaboration with Dr. Robert Collier of OR St. Univ. Surfur from these water samples will be extrqacted via ion exchange resin and measured for its isotopic composition at the Geological Survey of Canada. ;Bulk surfur extractions on these samples was completed during 11/12-17/99 at the Univ. of Ottowa. Sulfur concentrations determined in ;these samples range from 30 ppm to 160 ppm and the silver sulfide will be analyzed for isotopic composition during the period Feb.-March 2000. ;Hydrogen isotopic analyses of pure glass ;separates from these 20 samples will be done ;during the months of Mar.-Apr. 2000.;Electron micorprobe analyses of the sulfur concentration in glass inclusions has been completed at the American Museum of Natural History. Sulfur concentrations in Mazama rhyodacitic glalss inclusions reach a max. of 450 ppm, thus indicating extensive (70-94%) sulfur degassing when compared to sulfur concentrations determined in pure matrix glass separates via bulk extraction. Chlorine concentrations in rhyodacitic inclusions reaches a maximum of approx. 3500 ppm indication 50% degassing of Cl. Sulfur concentrations in andesitic glass inclusions from andesitic scoria reach a max. of 2700 ppm and chorine concentrations range up to 4000 ppm. Sulfur degassing from this magmatic component was at least 98-99%. I have recently begun Infra-red spectroscopic studies of dissolved water and carbon dioxide in Mazama glass inclusions. A minimum estimate of sulfur degassing during the Climactic eruption of Mt. Mazama is 3.1 x 10 (to the 13th power)gS.

For this study, were one or more specimens collected and removed from the park but not destroyed during analyses? No

Funding provided this reporting year by NPS: 0

Funding provided this reporting year by other sources: 0

Full name of college or university:  n/a

Annual funding provided by NPS to university or college this reporting year: 0


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