Hydrogen, Oxygen and Sulfur Isotope Studies of Seafloor Hydrothermal System at the Desmos Caldera, Manus Back‐arc Basin, Papua New Guinea: An Analogue of Terrestrial Acid Hot Crater‐lake

Abstract

Abstract:The Onsen site is an active submarine hydrothermal system hosted by the Desmos caldera in the Eastern Manus Basin, Papua New Guinea. The hydrothermal fluid is very acidic (pH=1.5) and abundant native sulfur is deposited around the vent. The δ 34 S values of native sulfur range from -6.5 to -9.3 ‰. δ 34 S values of H 2 S and SO 4 in the hydrothermal fluid are -4.3 to -9.9 ‰ and +18.6 to +20.0 ‰, respectively. These δ 34 S values are significantly lower than those of the other hydrothermal systems so far reported. These low δ 34 S values and the acidic nature of the vent fluids suggest that volcanic SO 2 gas plays an important role on the sulfur isotope systematic of the Onsen hydrothermal system. Relationship among the δ 34 S values of S-bearing species can be successively explained by the model based on the disproportionation reaction starting from the volcanic SO 2 gas. The predicted δ 34 S values of SO 2 agree with the measured whole rock δ 34 S values. δD and δ 18 O values of clay minerals separated from the altered rock samples also suggest the contribution of the magmatic fluid to the hydrothermal system. Present stable isotopic study strongly suggests that the Onsen hydrothermal site in the Desmos caldera is a magmatic submarine hydrothermal system.

Origin of a native sulfur chimney in the Kueishantao hydrothermal field, offshore northeast Taiwan

“…Obviously, the δ 34 S values of the Kueishantao native sulfur chimney are lower, which exclude the possibility that the sulfur in the Kueishantao native sulfur chimney comes directly from the Kueishantao andesite. Also, the sulfur isotopic composition is much closer to that of mid-ocean ridge basalt (δ 34 S = +0.1‰±0.5‰ [29] ), suggesting that the sulfur of the Kueishantao native sulfur chimney comes from deep magma, which can be explained by deep magma degassing.…”

“…All these data indicate that the sulfur sources of the Kueishantao native sulfur chimney differ from those of the native sulfur in the Okinawa Figure 4 Comparison of the sulfur isotope values of native sulfur samples from different seafloor hydrothermal fields with the andesite and different sulfur sources. Data from Kueishantao native sulfur from Chen et al [12] , andesite from Ueda and Sakai [23] and Woodhead et al [24] , seawater from Rees et al [25] , Jade native sulfur from Marumo et al [26] and Zeng et al [27] , Lau Basin native sulfur from Herzig et al [28] , Onsen native sulfur from Gena et al [29] , MORB (Mid-Ocean Ridge Basalt) from Sakai et al [30] .…”

The five stable isotope compositions of Fig Tree barites: Implications on sulfur cycle in ca. 3.2Ga oceans

“…Given the mounting evidence that early Archean magma was no more reduced or oxidized than the modern one (Canil, 2002;Li and Lee, 2004) and that sulfate of SO 2 -disproportionation origin is common in similar modern systems (Hattori and Cameron, 1986;Gamo et al, 1997;Kusakabe et al, 2000;Gena et al, 2006), the possibility of a f mh sulfate in early Archean cannot be dismissed. It is probable that both subaerial and submarine f mh sulfate contributed to the sulfate reservoir in early Archean ocean.…”

Geochemistry of deep-sea hydrothermal vent fluids from the Mid-Cayman Rise, Caribbean Sea

“…at PACMANUS. disproportionation is occurring at these locations (GAMO et al, 1997;GENA et al, 2006;KIM et al, 2004;. Although negative δ 34 S values could be derived from biogenic pyrite in abundant surface sediment less than one kilometer away (HRISCHEVA et al, 2007), the low abundance of CH 4 (an expected thermogenic sedimentary alteration product) in acid-sulfate fluids with the most negative δ 34 S values suggests sedimentary sulfur sources are not signficant.…”