Conical Vent

Latitude: 19.542^οN Longitude: 146.648^οE Depth: 3144 m bsl

Conical Seamount is a smooth sided, nearly circular forearc serpentine mud volcano with a slightly flattened summit region (Fryer, 1996) that is located adjacent to a large forearc graben (Fryer et al., 1990; Fryer, 1992; Newsom, 1992). Conical Seamount is considered active because of the discovery of recent mud extrusions and the venting of fluids with deep slab origins [Fryer and Mottl, 1992]. The fluids are actively flowing through carbonate and silicate chimneys and have elevated pH, high alkalinity and enrichments in CH₄, SiO₂, SO₄^2-, and H₂S. Methane and sulfate in the fluids are probably generated during serpentinization reactions between peridotite and slab derived fluids (Fryer, 1990). Some bacterial mats, small limpets and gastropods are associated with these vents.

Table 1: Operations history for Conical vent

Ship/ Platform	Operation	Year	Dive Number	References
KR06-15 Kaiko	Not found	2006 November	0369	JAMSTEC E-library of Deep-sea Images (JEDI) (note: search “Conical”) KR06-15 cruise report
Not found	SeaMARK II bathymetry data	Not found	Not found	Fryer et al., 1996; Fryer et al., 1992
Not found	Seasat A Satellite Scatterometer (SASS) data	Not found	Not found	Fryer et al., 1996; Fryer et al., 1992
TN-154 Thompson/ ROV Jason-2	Not found	2003 April	J2-032	Woods Hole Oceanographic Institution: ROV JASON/MEDEA: Operations Summary (note: click “Files- operations summary”)
YK03-07 Yokosuka/ Shinkai 6500	Not found	2003 September	785	YK03-07 cruise report

Table 2: Vent activity and host rocks

Activity and Host Rocks		References
Activity	Active mud volcanism	Fryer and Mottl., 1992; Fryer., 1990; IODP-MCME 366 Proposal; Savov et al., 2005
Host Rocks	Serpentinized harzburgite and dunite	Fryer et al., 1990; Savov et al., 2005

Table 3: Vent fluid characteristics

	Bottom seawater	Vent Fluids	References
Distance from the trench (km)		90	IODP-MCME 366 Proposal
Temperature (^οC)		13.5 ^οC (hole 780D); 1.5^οC	Fryer et al., 1990(c); Mottl et al., 2003
pH	7.72	9.28	Fryer et al., 1990
		>9.2, 12.5	Hulme et al., 2010, Fryer et al., 1990 b
Composition		Indicate deep seated serpentinization sources, enriched in CH₄, SiO₂, SO₄^2-, H₂S	Fryer et al., 1990
Alkalinity (meq/kg)	2.3	High, 41	Fryer et al., 1990
Clorinity (mmol/kg)	542	260	IODP-MCME 366 Proposal
CH₄(mmol/kg)	4×10-7	2±1	Mottl et al., 2003
Mn (μmol/kg)	0	<0.01	IODP-MCME 366 Proposal
Fe (μmol/kg)	0	2	IODP-MCME 366 Proposal
Sulfate (mmol/kg)	28	46	IODP-MCME 366 Proposal
Mg (mmol/kg)		0.009	Fryer et al., 1990 b
Ca (mmol/kg)		0.6	Fryer et al., 1990 b
Na (mmol/kg)	466	390	IODP-MCME 366 Proposal
K (mmol/kg)	10.1	15	IODP-MCME 366 Proposal
Li (μmol/kg)	26	1.6	IODP-MCME 366 Proposal
Rb (μmol/kg)	1.37	7.8	IODP-MCME 366 Proposal
Sr (μmol/kg)	90	20	IODP-MCME 366 Proposal
Ba (μmol/kg)	0.14	0.1	IODP-MCME 366 Proposal
B (μmol/kg)	410	3900	IODP-MCME 366 Proposal
Si (μmol/kg)	190	60	IODP-MCME 366 Proposal

* IODP-MCME 366- International Ocean Discovery Program-Mariana Convergent Margin Expedition 366.

Table 4: Vent Biology

General name	Phylum	Class/Order	Family	Genus/Species	References
Bacterial mats	Bacteria				Fryer et al., 1990
Fish	Chordata	Anguilliformes			JAMSTEC E-library of Deep-sea Images (JEDI) (note: search “Conical seamount”)
Gastropods	Mollusca				Fryer et al., 1990
Sea anemone	Cnidaria	Actiniaria	Boloceroididae		JAMSTEC E-library of Deep-sea Images (JEDI) (note: search “Conical seamount”)
Sea cucumbers	Echinoderms	Holothuroidea	Pelagothuriidae	Enypniastes eximia	JAMSTEC E-library of Deep-sea Images (JEDI) (note: search “Conical seamount”)
Shrimp	Arthropoda	Decapoda			JAMSTEC E-library of Deep-sea Images (JEDI) (note: search “Conical seamount”)
Small Limpets	Mollusca				Fryer et al., 1990
Sponge	Porifera				JAMSTEC E-library of Deep-sea Images (JEDI) (note: search “Conical seamount”)

Images:

J-EDI JAMSTEC E-library of Deep-sea Images http://www.godac.jamstec.go.jp/jedi/public/Sec101.jsf note: search “Conical”.

Video Links: None known

References:

Fryer, P., Saboda, K. L., Johnson, L. B., Mackay, M. E., Moore, G. F., Sto¡ers, P., 1990. Conical Seamount: SeaMARK II, Alvin submersible, and seismic reflection studies. Proc. ODP Init. Rep. 125, 69-80.
Fryer, P., Mottl, M. J., 1992. Lithology, mineralogy, and origin of serpentine muds recovered from Conical and Torishima forearc seamounts: results of Leg 125 drilling, Proc. ODP Sci. Results 125, 343-362.
Fryer, P, 1996. Evolution of the Mariana convergent plate margin system. Reviews of Geophysics 31 (1), 89-125.
Mottl, M. J., Komor, S. C., Fryer, P., Moyer, C. L., 2003. Deep-slab fluids fuel extremophilic Archaea on a Mariana forearc serpentinite mud volcano: Ocean Drilling Program Leg 195. Geochemistry, Geophysics, Geosystems 4 (11) 9009, doi: 10.1029/2003GC000588.
Savov, I. P., Ryan, J. G., D’Antonio, M., Kelley, K., Mattie, P., 2005. Geochemistry of serpentinized peridotites from the Mariana Forearc Conical Seamount, ODP Leg 125: Implications for the elemental recycling at subduction zones. Geochem.Geophys. Geosyst., 6, Q04J15, doi: 10.1029/2004GC000777.

Website References:

J-EDI JAMSTEC (Japan Agency for Marine Earth Science and Technology) E-library of Deep-sea Images: http://www.godac.jamstec.go.jp/jedi/public/Sec101.jsf (accessed 11/24/2015)
Woods Hole Oceanographic Institution: ROV JASON/MEDEA: Operations Summary http://www.whoi.edu/main/jason/operations-summary (accessed 11/24/2015)

Cruise Reports:

IODP Mariana Convergent Margin Expedition 366, unpublished IODP proposal http://iodp.tamu.edu/scienceops/precruise/mariana/505-Full5.pdf (accessed 01/19/2016)
Kairei cruise report KR06-15 http://www.godac.jamstec.go.jp/catalog/data/doc_catalog/media/KR06-15_leg1-2_all.pdf (accessed 01/19/2016)
Yokosuka cruise report YK03-07 http://www.godac.jamstec.go.jp/catalog/data/doc_catalog/media/YK03-07_all.pdf (accessed 01/19/2016)