Oceanography The Official Magazine of
The Oceanography Society
Volume 23 Issue 01

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Volume 23, No. 1
Pages 174 - 175

SPOTLIGHT • South Chamorro Seamount

C. Geoffrey Wheat Patricia Fryer Ken TakaiSamuel Hulme
First Paragraph

Sixteen large, active serpentinite mud volcanoes exist in the Mariana forearc, the region of seafloor between the Mariana Trench and the volcanic island arc (Fryer et al., 2006). Up to 50 km in diameter and rising as much as 2.4 km above the surrounding seafloor, these seamounts form as a consequence of subduction processes, which generate deep-seated faults that penetrate the crust and mantle of the overriding Mariana microplate to the depth of the underlying and subducting Pacific Plate (Figure 1). Faults that are observed up to 100 km west of the Mariana trench provide a pathway for the ascent of fluid released from dehydration reactions within the subducting Pacific Plate and for the ascent of ground-up rock fragments. As this fluid upwells, it reacts with the overlying mantle, producing serpentine, hydrogen gas, and alkaline fluids (up to pH 12.5).


Wheat, C.G., P. Fryer, K. Takai, and S. Hulme. 2010. Spotlight 9: South Chamorro Seamount. Oceanography 23(1):174–175, https://doi.org/10.5670/oceanog.2010.81.


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Hulme, S.M., C.G. Wheat, P. Fryer, and
M.J. Mottl. 2010. Pore water chemistry of the Mariana serpentinite mud volcanoes: A window to the seismogenic zone. Geochemistry, Geophysics, Geosystems 11, Q01X09, http://10.1029/2009GC002674

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Takai, K., C.L. Moyer, M. Miyazaki, Y. Nogi, H. Hirayama, K.H. Nealson, and K. Horikoshi. 2005. Marinobacter alkaliphilus sp. nov.: A novel alkaliphilic bacterium isolated from subseafloor alkaline serpentine mud from Ocean Drilling Program Site 1200 at South Chamorro Seamount, Mariana Forearc. Extremophiles 9:17–27.

Wheat, C.G., P. Fryer, A.T. Fisher, S. Hulme, H. Jannasch, M.J. Mottl, and K. Becker. 2008. Borehole observations of fluid flow from South Chamorro Seamount, an active serpentinite mud volcano in the Mariana forearc. Earth and Planetary Science Letters 267:401–409.