HR: 0800h
AN: V51C-1498    [Abstracts]
TI: Carbon Fluxes from Submarine Arc Volcanoes - examples from the Mariana and Kermadec Arcs
AU: * Lupton, J
EM: john.e.lupton@noaa.gov
AF: NOAA, PMEL, Newport, OR 97365 United States
AU: Butterfield, D
V51C-1498 AF: JISAO, Univ. of Washington, Seattle, WA 98115 United States
AU: Lilley, M
V51C-1498 AF: School of Oceanography, Univ. of Washington, Seattle, WA 98115 United States
AU: Evans, L
V51C-1498 AF: CIMRS, Oregon State University, Newport, OR 97365
AU: Greene, R
V51C-1498 AF: CIMRS, Oregon State University, Newport, OR 97365
AU: Resing, J
V51C-1498 AF: JISAO, Univ. of Washington, Seattle, WA 98115 United States
AU: Embley, R
V51C-1498 AF: NOAA, PMEL, Newport, OR 97365 United States
AU: Massoth, G
V51C-1498 AF: Inst. of Geological and Nuclear Sciences, PO Box 31, Lower Hutt, 31-312 New Zealand
AU: Christenson, B
V51C-1498 AF: Inst. of Geological and Nuclear Sciences, PO Box 31, Lower Hutt, 31-312 New Zealand
AU: de Ronde, C
V51C-1498 AF: Inst. of Geological and Nuclear Sciences, PO Box 31, Lower Hutt, 31-312 New Zealand
AU: Olson, E
V51C-1498 AF: School of Oceanography, Univ. of Washington, Seattle, WA 98115 United States
AU: Proskurowski, G
V51C-1498 AF: Dept. of Marine Chemistry and Geochemistry, WHOI, Woods Hole, MA 02543 United States
AU: Nakamura, K
V51C-1498 AF: NAIST, Ibaraki, Tsukuba, 305-8567 Japan
AU: Schmidt, M
V51C-1498 AF: Inst. of Geosciences, Univ. of Kiel, Kiel, 24118 Germany
AU: Stoffers, P
V51C-1498 AF: Inst. of Geosciences, Univ. of Kiel, Kiel, 24118 Germany
AU: Worthington, T
V51C-1498 AF: Inst. of Geosciences, Univ. of Kiel, Kiel, 24118 Germany
AU: Hannington, M
V51C-1498 AF: Dept. of Earth Sciences, Univ. of Ottawa, Ottawa, K1N 6N5 Canada
AB: Recent investigations of volcanic arcs have revealed unusually high fluxes of CO₂ from several submarine arc volcanoes. In 2004 the ROPOS ROV was used to map and sample ~10 active volcanoes along the Mariana arc, and in 2005 a similar study of volcanoes along the Kermadec arc was conducted using the HURL Pisces submersible. Of particular interest are 3 volcanoes that, in addition to discharging hot vent fluid, were found to be venting a separate CO₂-rich phase in the form of gas bubbles or, in one case, droplets of liquid CO₂. The Champagne hydrothermal site situated at ~1600-m depth near the summit of NW Eifuku volcano (21.49°N, 144.04°E) in the northern Mariana Arc, was discovered in 2004 during NOAAs Submarine Ring of Fire (SROF) project. This unusual site was discharging two distinct fluids from the same vent field: a 103°C gas-rich hydrothermal fluid, and cold (4°C) droplets of liquid CO₂. The hot fluid contained ~2.2 moles/kg CO₂, the highest ever reported for submarine hydrothermal fluids and about twice the saturation value at that p,T. The carbon flux from this site was estimated to be ~23 moles CO₂/sec, about 0.1% of the global MOR carbon flux. Two similar but much shallower CO₂-rich systems were discovered on the Kermadec arc. Pisces dives on Giggenbach volcano (30.04°S, 178.71°W) in the Kermadec arc discovered a mixture of gas bubbles and 203°C fluid discharging at 164-m depth. The fluid contained 250 - 500 mM/kg total gas. At Volcano 1 (21.15°S, 175.75°W), Pisces found streams of gas bubbles rising from the seafloor at ~100 m depth. This vent area had areas of diffuse discharge (30 to 150°C) with gas contents up to 130 mM/kg. Although analyses are still in progress for these two sites, the gas bubbles are assumed to be mainly CO₂. It is notable that discharges of pure CO₂ have never been reported for MOR hydrothermal systems, and only one other submarine occurrence of liquid CO₂ has been reported (in the Okinawa Trough, a back-arc system). This suggests that such CO₂-rich systems occur much more frequently in subduction zone systems compared to MOR systems, probably due to the supply of subducted marine carbonates and organic matter. It seems likely that the high CO₂ levels arise from direct degassing from a magma chamber and/or de-volatilization of the subducting slab. The apparent high carbon flux from these sites suggests that submarine arc volcanoes may play a larger role in oceanic carbon cycling than previous realized.
DE: 1031 Subduction zone processes (3060, 3613, 8170, 8413)
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 4832 Hydrothermal systems (0450, 1034, 3017, 3616, 8135, 8424)
DE: 8424 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8135)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005