PROPOSED SITESSite MAF-4B
It is likely that this seamount is an active serpentine mud volcano similar to Conical Seamount (Fryer et al., in press) and would provide an excellent drill target for studies of the active processes of these mud volcanoes. It has the strongest slab-signature in pore fluids from among the seamounts sampled in 1997 (Wheat and Mottl, submitted) and is second only to Conical Seamount in strength of slab signal.
Proposed Site WP-1B is situated on flat seafloor at a water depth of 5640 mbsl ~100 km west of the Kyushu-Palau Ridge axis along the eastern edge of the west Philippine Basin. The site lies on Chron 21, suggesting a basement age of 49 Ma. The sediment section is predicted to be ~400 to 450 m thick based on recent seismic reflection surveys showing a two-way traveltime to basement of 0.5 s. Drilling at other sites in the region on DSDP Legs 31 and 59 (Karig, Ingle, et al., 1975; Kroenke, Scott, et al., 1980) recovered a relatively barren, deep-water section dominated by Holocene to Eocene/Paleocene(?) brown pelagic silty clays overlying basement near the Oki-Daito Ridge (DSDP Sites 294/295). At DSDP Sites 290 and 447 to the south, the section consists of a barren interval of Pliocene clays underlain by Oligocene nannofossil-bearing silty clays mixed with ash. This was underlain by a thick section of polymict and volcanic breccias presumably derived from the Kyushu-Palau Ridge. The underlying basement consists of 80% basalt pillows and 20% dolerite. Because Site WP-1B lies in a similar setting at the foot of the Kyushu-Palau Ridge, it is likely that the section at the proposed site will be similar to that at Sites 290 and 447.
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