DEB BERGFELD

	U.S. Geological Survey MS #434 345 Middlefield Rd. Menlo Park, CA 94025 Tel: (650) 329-4657 dbergfel@usgs.gov

 

Education
B.S., Geology University of Missouri-Columbia (1991)

M.S., Geochemistry University of Missouri-Columbia (1994)

Ph.D., Geochemistry University of New Mexico-Albuquerque (2001)

Research Interests
My research interests focus on using data from surface degassing features in geothermal and volcanic regions to assess the source of gas emissions, quantify the flux of magmatic volatiles, estimate heat fluxes, and examine the relationship of ground water flow to the gas emissions. In the field I collect water and gas samples from thermal and cold springs, fumaroles, low-temperature gas vents, and diffuse gases from areas of vegetation kill. Typical sample analyses include trace and major element chemistry, ¹⁴C-CO₂, d¹³C-CO₂, dD and d¹⁸O. For much of my work I also use a field-portable infrared CO₂ analyzer to measure the flux of diffuse CO₂ emissions from the soil. This instrument allows me to locate areas of excess degassing and quantify total emissions of CO₂.

 

Research Projects

Long Valley caldera, CA

Since Feb. 2003 we have investigated 13 areas of vegetation kill in and around the resurgent dome at Long Valley caldera, CA. Results from CO₂ flux measurements and gas geochemistry have been used to quantify anomalous CO₂ emissions and refine thermal fluid flow paths around the resurgent dome. Recent work includes a heat flow study from two sites near the Casa Diablo power plant.

Cascades Range Volcanoes

Investigations of gas emissions and CO₂ fluxes in young volcanic terrains. Recent field studies include Mt. St. Helens , WA and Mt. Hood, OR. Future work may include Lassen CA .

• Gas and water samples collected on Mt. St. Helens in Aug. 2002 were more dilute than samples collected from the same features in 1994 but showed the continued presence of magmatic volatiles. We hope to resample these locations in 2005 to see if there are post-eruptive changes in the composition of the thermal springs.
• Diffuse flux measurements made on Mt. Hood indicate that CO₂ emissions from thermal ground near the summit of Mt. Hood are only around 6 to 7 tons per day.

Alaska

In June 2004 we initiated gas surveys at Shrub Mud Volcano in the Wrangell Mts. AK and in the vicinity around Gas Rocks, on the south shore of Becharof Lake on the Alaskan peninsula. The Shrub field site had recently collapsed into a single pool so our flux measurements were mostly confined to sites around the circumference of the pool.

Other areas of interest

Although most of my work involves studies in volcanic areas I am interested in understanding CO₂ emissions in other natural systems. I have recently returned from a field investigation of diffuse CO₂ and Hg emissions at the Dixie Valley geothermal field in west-central Nevada and I have completed three soil-gas surveys to investigate leakage of CO₂ from natural reservoirs Colorado Plateau. Sites over large CO₂ reservoirs in UT and AZ were chosen as analogues for downhole geologic sequestration of anthropogenic CO₂. This work was done in conjunction with the Utah Geological Survey and the Energy and Geoscience Institute at the University of Utah.

Publications

Bergfeld, D., Evans, W. C., Howle, J. F., and Farrar, C. D., 2006, Carbon dioxide emissions from vegetation-kill zones around the resurgent dome of Long Valley caldera, eastern California, USA: Journal of Volcanology and Geothermal Research, 152 (1-2) 140-156. abstract

Lewicki, J.L., Bergfeld, D., Cardellini, C., Chiodini, G., Granieri, D., Varley, N., Werner C. 2005. Comparative soil CO₂ flux measurements and geostatistical estimation methods on Masaya volcano, Nicaragua Bulletin of Volcanology, 68 (1) 76-90. abstract

Bergfeld, D., Howle, J.F., and Schmidt, M.E., 2004. Diffuse CO₂ degassing from summit areas on Mt. Hood , Oregon , USA . In: Wanty, R.B., and Seal, R.R., II, eds., Water Rock Interaction, v. 1, Proceedings of the Eleventh International Symposium on Water, Saratoga Springs, New York, July 2004: New York, A.A. Balkema, p. 83-86.

White, S.P, Allis, R.G., Bergfeld, D., Moore, J.N., Chidsey, T.C., Morgan, C., McClure, K., and Rauzi, S., 2004. Evaluating the seal integrity of natural CO₂ reservoirs of the Colorado Plateau, Third Annual Conference on Carbon Sequestration, 3-6 May, Alexandria , VA.

Bergfeld, D., Goff, F.E., and Janik, C.J., 2001. Elevated Carbon Dioxide Flux at the Dixie Valley Geothermal Field, Nevada: Relations Between Surface Phenomena and the Geothermal Reservoir. Chemical Geology, (2) 177, 43-66. abstract

Bergfeld, D., Goff, F.E., and Janik, C.J., 2001. Carbon Isotope Systematics and CO₂ Sources in The Geysers-Clear Lake Region, Northern California. Geothermics, 30 (2/3) 303-331. abstract

Labotka, T. C., Bergfeld , D. ,Nabelek, P. I., 2000. Two diamictites, two cap carbonates, two d13C excursions, two rifts: The Neoproterozoic Kingston Peak Formation, Death Valley , California ; Comment. Geology, 28 (2), 191-192.

Bergfeld, D., Bruton, C., Goff, F.E., and Counce, D., 1999. Preliminary Evaluation of Geothermal Potential at the Cheyenne River Sioux Reservation, South Dakota. Geothermal Resources Council Transactions 23, 453-459.

Bergfeld, D., Goff, F.E., and Janik, C.J., 1998. CO₂ Flux Measurements Across Portions of the Dixie Valley Geothermal System, Nevada. Geothermal Resources Council Transactions 22, 107-111.

Bergfeld, D., Nabelek, P.I., Labotka, T.C., 1996. Carbon Isotope Exchange During Polymetamorphism in the Panamint Mountains, California. Journal Metamorphic Geology 14, 199-212. abstract