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

By C. Geoffrey Wheat , Patricia Fryer , Ken Takai, and Samuel Hulme 
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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.


Fryer, P., and M.J. Mottl. 1997. Shinkai 6500 investigations of a resurgent mud volcano on the Southeastern Mariana forearc. JAMSTEC Journal of Deep Sea Research 13:103–114.

Fryer, P., J. Gharib, K. Ross, I. Savov, and M.J. Mottl. 2006. Variability in serpentinite mudflow mechanisms and sources: ODP drilling results on Mariana forearc seamounts. Geochemistry, Geophysics, Geosystems 7, Q08014, http://10.1029/2005GC001201.

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

Oakley, A.J., B. Taylor, and G.F. Moore. 2008. Pacific Plate subduction beneath the central Mariana and Izu-Bonin fore arcs: New insights from an old margin. Geochemistry, Geophysics, Geosystems 9(6), http://10.1029/2007GC001820.

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.

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