HR: 0800h
AN: V21D-0749    [Abstracts]
TI: Variable Basement Compostion and Magma Degassing Affecting Hydrothermal Systems in the Eastern Manus Basin
AU: * Bach, W
EM: wbach@uni-bremen.de
AF: University of Bremen Department of Geosciences, Klagenfurter Str. 2, Bremen, 28359, Germany
AU: * Bach, W
EM: wbach@uni-bremen.de
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Tivey, M
EM: mtivey@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Seewald, J
EM: jseewald@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Tivey, M
EM: mktivey@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Craddock, P
EM: pcraddock@whoil.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Yoerger, D
EM: dyoerger@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, United States
AB: In August 2006, hydrothermal activity within the eastern Manus Basin was investigated using a combination of mapping and sampling (using AUV ABE and ROV Jason2). Objectives included identifying geological settings, examining interactions of seawater with felsic rocks, and determining the extent of volatile magmatic inputs into these systems. Hydrothermal systems in the eastern Manus Basin show a range in (1) fluid composition, (2) massive sulfide composition, and (3) rock alteration style that all point to input of magmatic volatiles into the hydrothermal system that varied in space and time. Basement compostions range from fresh arc basalt to rhyolite, with compositions following a classic calc-alkaline trend. The most felsic rocks display a wide range in volatiles dissolved in glass. Rhyolitic lavas form the Roman Ruins Vent Field in the PACMANUS area have high chlorine contents that plot along a conservative trend. Rhyolites from North Su volcano, in contrast, show more variable but generally much lower Cl contents, indicating more pronounced degassing in that area. Vent fluids exhibit great compositional variability between and within the vent fields. Fluids are variably enriched in carbonic and sulfuric acid, indicative of degassing of CO2 and SO2. Evidence for present and past SO2 degassing is preserved in the form of native sulfur and advanced argillic rock alteration, predominantly in parts of PACMNUS, at SuSu Knolls and at Desmos.
DE: 1034 Hydrothermal systems (0450, 3017, 3616, 4832, 8135, 8424)
DE: 3017 Hydrothermal systems (0450, 1034, 3616, 4832, 8135, 8424)
DE: 3616 Hydrothermal systems (0450, 1034, 3017, 4832, 8135, 8424)
DE: 4832 Hydrothermal systems (0450, 1034, 3017, 3616, 8135, 8424)
DE: 8135 Hydrothermal systems (0450, 1034, 3017, 3616, 4832, 8424)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting