West Rota Vent

Latitude: 14.325^οN Longitude: 144.833^οE Depth: 309 m bsl

West Rota is a very large caldera on the Mariana arc, is approximately 8 km in diameter. Studies conducted in 2003 at West Rota revealed fluid enrichments in both Mn and Δ³He within the caldera (Stern et al., 2008), and later found that the vent is weakly active (Resing et al., 2009). Detailed ROV surveys in 2004 and 2005 discovered small patches of low-temperature venting at the base of the SE caldera wall (Stern et al., 2008). Apart from the chemistry, biodiversity of W Rota includes anemones and crinoids (Submarine Ring of Fire, 2004).

Table 1: Operations history for W Rota vent

Ship/ Platform	Operation	Year	Dive Number	References
NT 0517 R/V Natsushima/ Hyper-dolphin	Not found	2005 October	HPD#0482 to HPD#0484, HPD#0488, HPD#0489	NT05-17 cruise report
TN-153 R/V T. G. Thompson	EM 300 multibeam; CTD Verical cast	2003 February – March	Not found	Submarine Ring of Fire 2003
TN-167 R/V T. G. Thompson/ ROPOS	CTD tow-yo, CTD vertical cast, EM 300	2004 February – March	R785	Submarine Ring of Fire 2004

Table 2: Vent activity and host rocks

Activity and host rocks

References

Activity

Extinct/ Dormant

Embley et al., 2007

Host Rocks

Basalt, Andesite and Dacite

Embley et al., 2007;

Stern et al., 2008

Table 3: Vent fluid characteristics

Vent Fluids		References
Temperature (^οC)	Low T (<~100^οC)	Embley et al., 2007
ΔpH	0.006	Resing et al., 2009
Composition	Small Fe, Mn, and ³He	Resing et al., 2009
TDMn (nM)	12	Resing et al., 2009
TDFe (nM)	12	Resing et al., 2009
Δ³He (fM)	0.12	Resing et al., 2009

* ΔpH – Measured relative to the regional background; Δ³He – Measured above the background.

Table 4: Vent Biology

General name	Phylum	Order/ Class	References
Anemone	Cnidaria		Submarine Ring of Fire, 2004
Stalked Crinoid	Echinodermata	Crinoidea	Submarine Ring of Fire, 2004

Images:

A stalked crinoid

A purple anemone

Video Links:

Fly-through over West Rota volcano

References:

Embley, R. W., Baker, E. T., Butterfield, D. A., Chadwick, W. W. Jr., Lupton, J. E., Resing, J. A., de Ronde, C. E. J., Nakamura, K., Tunnicliffe, V., Dower, J. F., Merle, S. G., 2007. Exploring the submarine ring of fire: Mariana Arc- Western Pacific, Oceanography 20, 68–79.
Resing, J. A., Baker, E. T., Lupton, J. E., Walker, S. L., Butterfield, D. A., Massoth, G. J., Nakamura, K., 2009. Chemistry of hydrothermal plumes above submarine volcanoes of the Mariana Arc. Geochemistry, Geophysics, Geosystems 10 (2), doi:10.1029/2008GC002141.
Stern, R. J., Tamura, Y., Embley, R. W., Ishizuka, O., Merle, S. G., Basu, N. K., Kawabata, H., Bloomer, S. H., 2008. Evolution of West Rota Volcano, an extinct submarine volcano in the southern Mariana Arc. Evidence from sea floor morphology, remotely operated vehicle observations and ⁴⁰Ar-³⁹Ar geochronological studies. Island Arc 17 (1), 70-89.

Website References:

JAMSTEC (Japan Agency for Marine Earth Science and Technology) E-library of Deep-sea Images (JEDI) http://www.godac.jamstec.go.jp/jedi/public/Sec102.jsf (accessed 10/03/2015)
Submarine Ring of Fire 2003 http://oceanexplorer.noaa.gov/explorations/03fire/logs/summary/summary.html (accessed 10/03/2015)
Submarine Ring of Fire 2004 http://oceanexplorer.noaa.gov/explorations/04fire/logs/summary/summary.html (accessed 10/03/2015)

Cruise Reports:

Natsushima cruise report NT05-17 http://www.godac.jamstec.go.jp/catalog/data/doc_catalog/media/NT05-17_all.pdf (accessed 2/27/2017)
Submarine Ring of Fire 2003 http://oceanexplorer.noaa.gov/explorations/03fire/logs/summary/marianas_cruisereport.pdf (accessed 2/27/2017)
Submarine Ring of Fire 2004 http://oceanexplorer.noaa.gov/explorations/04fire/logs/summary/media/marianas2004cruisereport.pdf (accessed 2/27/2017)