Notes on Vent Field Description:
off-axis caldera, lying between the Northeast Lau Spreading Center (NELSC) and the northern Tofua arc; 15-km diam caldera with central cone Motutahi; SS11/2004 cruise: "the most spectacular retrieval of massively altered and sulfide-bearing lithologies was from Target O."; magnetic data also suggests active hydrothermal field (Kwak et al. 2006); Merle et al. (2008): tow t08c15; "Directly east of the NELSC the seafloor is dominated by an impressive circular volcanic caldera named Volcano “O”. Backscatter data acquired during our bathymetric surveys showed that Volcano O is the source of several lava flows covering large areas of the seafloor. Our plume surveys showed that Volcano O is also host to several active hydrothermal vents." (http://www.pmel.noaa.gov/vents/laubasin/lau-2008/lau08-nov27.html); Resing et al. (2010) indicate that this site may be confirmed active as of May 2009 ROV Jason II: "Observations of hydrothermal activity at two sites were made within the caldera at Volcano “O”"; May 2010 NOAA cruise report camera tow: "In response to the discovery of a very intense sulfur-rich plume over the dacite cone in the SE corner of Volcano O, Tow 8 found concentrated venting of sulfur near its summit at ~1280 m"
Year and How Discovered (if active, visual confirmation is listed first):
2009 ROV Jason II; 2003 plume only; 2004 dredging (SS11/2004 cruise); 2005 plume only; 2008 commercial ROV (report does not confirm activity)
Discovery References (text):
cruise report NoToVE-2004, SS11/2004, http://www.cmar.csiro.au/datacentre/process/data_files/cruise_docs/ss2004_v11_summary.pdf, accessed 28 May 2015
(plume only) Kim, J. et al. (2009) Venting sites along the Fonualei and Northeast Lau Spreading Centers and evidence of hydrothermal activity at an off-axis caldera in the northeastern Lau Basin. Geochemical Journal 43: 1-13
(deposits only) http://www.nautilusminerals.com/s/Media-NewsReleases.asp?ReportID=319379&_Type=News-Releases&_Title=Teck-Cominco-Discovers-Four-High-grade-Copper-Gold-Zinc-SMS-Systems-in-Tonga, accessed 28 May 2015: Tunu-Sosisi SMS
SRK Consulting report for Nautilus Minerals, http://www.nautilusminerals.com/i/pdf/2008NautilusExplorationNI43-101Report.pdf, accessed 28 May 2015
Resing, J. A., et al. (2010) Hydrothermal Activity and its Chemical Characteristics in the NE Lau Basin. AGU Fall Meeting Abstract #T13B-2187.
Other References (text):
(magnetics) Kwak et al. 2006 AGU Fall Meeting abstract #T51B-1529
Arculus "Arc-backarc systems of northern Kermadec-Tonga" (http://www.crownminerals.govt.nz/cms/pdf-library/minerals/conferences-1/045_papers_44.pdf)
Merle, S., et al. (2008) Northeast Lau Basin, R/V Thompson Expedition TN227, November 13-28, 2008, Apia to Apia, Western Samoa. Cruise report. Accessed 8 May 2015, http://www.pmel.noaa.gov/eoi/laubasin/documents/tn227-nelau-report-final.pdf.
Embley et al. (2009) Extensive and Diverse Submarine Volcanism and Hydrothermal Activity in the NE Lau Basin. AGU Fall Meeting abstract #V51D-1719.