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British scientists discover deepest known undersea volcanic vents 12 April 2010

Posted by admin in Caribbean, current research, submarine volcanism.
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First photograph of the world's deepest known 'black smoker' vent, erupting water hot enough to melt lead, 3.1 miles deep on the ocean floor (National Oceanography Centre)
First photograph of the world’s deepest known ‘black smoker’ vent, erupting water hot enough to melt lead, 3.1 miles deep on the ocean floor (National Oceanography Centre).

Scientists from the UK’s National Oceanography Centre (NOC) have discovered the deepest volcanic vents so far known, 5000 metres below the surface of the Caribbean Sea. The vents are located in the Cayman Trough in the western Caribbean, which reaches a maximum depth of 7,500 metres. Further research will analyse the geology and geochemistry of the vents and the marine life associated with them. NOC geochemist Dough Connelly, Principal Scientist of the expedition, says: ‘We hope our discovery will yield new insights into biogeochemically important elements in one of the most extreme naturally occurring environments on our planet’.

The Cayman Trough expedition, funded by the National Environment Research Council, is based aboard the UK’s new ocean-going research vessel RRS James Cook. For more on the expedition, see our post from August 2008: British scientists to investigate Caribbean deep-sea hydrothermal vents.

News
British scientific expedition discovers world’s deepest known undersea volcanic vents – EurekAlert, 11 April 2010
World’s deepest undersea vents discovered in Caribbean – BBC News, 12 April 2010
World’s deepest known undersea volcanic vents discovered – ScienceDaily, 12 April 2010

Information
National Oceanography Centre – website for the UK’s newly integrated National Oceanography Centre
Cayman Trough expedition – reports from the expedition team

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Seamounts galore in Oceanography special issue 24 February 2010

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Oceanography special issue: Mountains in the Sea (23:1 Mar 2010)

The latest issue (vol. 23, no. 1, March 2010) of the official magazine of The Oceanography Society, Oceanography, is devoted to the study of undersea mountains or seamounts. This special issue is entitled, not surprisingly, ‘Mountains in the Sea’ and features fascinating content by some very distinguished contributors, and, best news of all, the online version is free!

Seamount volcanism is an important theme in many of the articles, as might be expected. The following focus particularly on volcanic matters (links are direct to the PDFs):

There are also spotlight articles on particular seamounts, including the volcanically active Loihi, Vailulu’u and Northwest Rota-1 seamounts (links are direct to the PDFs).

The table of contents for this special issue of Oceanography gives direct links to all the content, and USGS director Marcia McNutt provides a foreword (PDF). Also: Oceanography home page, The Oceanography Society home page, and a press release at ScienceDaily.

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Fukutoku-Okanoba at the NASA Earth Observatory 12 February 2010

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Submarine Volcano Fukutoku-Okanoba Erupts (NASA Terra image, 9 February 2010)

Undersea volcano Fukutoku-Okanoba in the Japanese Volcano Islands erupted a few days ago, producing steam and ash, and discolouring the surrounding water. The NASA Earth Observatory has two nice images of this event captured on 9 and 11 February 2010. The first (detail above) was captured by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA’s Terra satellite on 9 February 2010, while the second (detail below) comes from the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite and was captured on 11 February 2010.

Submarine Volcano Fukutoku-Okanoba Erupts (NASA EO-1 image, 11 February 2010)

(Thanks to the NASA Earth Observatory team for citing this blog as a source.)

Information
Global Volcanism Program: Fukutoku-Okanoba – information from the GVP about Fukutoku-Okanoba (0804-13=)

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Volcanic origin for nickel ore deposits 21 November 2009

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Some 10% of the world’s nickel production comes from iron-nickel sulphide (or, if you prefer, sulfide) deposits laid down on seafloors between 2.5 and 3 billion years ago and found in those interesting ultramafic volcanic rocks called komatiites. How these deposits came to be there, however, has always been something of a mystery, for the ore requires sulphur to form and neither the magmas hosting the ore nor the seawater contained sufficient sulphur for the process. Clearly, if the sulphur doesn’t come from the magma or the seawater it must come from the substrate: because of the very high temperatures at which the magma was erupted (greater than 1500oC) it was able thermo-mechanically to erode its substrate, thus acquiring sulphur in areas where the substrate was sulphur-rich. But how did the sulphur come to be there in the first place?

In a paper entitled ‘Atmospheric sulfur in Archean komatiite-hosted nickel deposits’ (abstract) in the new issue of Science a team of scientists from the Carnegie Institution, Woods Hole Oceanographic Institution and the universities of Manitoba and Western Australia argue that it all starts with volcanoes. Sulphur dioxide was erupted by volcanoes into an anoxic atmosphere, where high levels of UV sunlight broke down the gas and allowed sulphur to descend via rainfall and accumulate on the seabed. There geothermal action formed it into sulphide which was combined with nickel in magmas to produce the iron-nickel sulphides found in komatiites. The unusual isotope sulphur-33, produced by the atmospheric breaking-down of the volcanic sulphur dioxide, has turned up in rocks found in Western Australia, providing scientists with the key to recreating the sulphur’s complex ancient journey.

  • Andrey Bekker, Mark E. Barley, Marco L. Fiorentini, Olivier J. Rouxel, Douglas Rumble, Stephen W. Beresford, ‘Atmospheric sulfur in Archean komatiite-hosted nickel deposits’, Science, Vol. 326. no. 5956 (20 Nov 2009), pp. 1086 – 1089. DOI: 10.1126/science.1177742. (abstract)

Early volcanoes minted nickel – ScienceNow Daily News, 21 November 2009
Rich ore deposits linked to ancient atmosphere – RedOrbit, 21 November 2009

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Undersea explosive eruptions named ‘neptunian’ 5 July 2009

Posted by admin in current research, geoscience, volcanology.
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Two researchers from the School of Earth Sciences and Centre of Excellence in Ore Deposits (CODES) at the University of Tasmania have come up with the name ‘neptunian’ to describe undersea explosive volcanic eruptions, says a report at ScienceDaily.

These eruptions are sustained and driven by gas exsolved from magma … Neptunian eruptions differ dramatically from magmatic-gas-driven explosive eruptions on land, reflecting the important influence of confining pressure and the higher heat capacity, density, and viscosity of water compared to air.

The original article (abstract here) by Sharon R. Allen and Jocelyn McPhie of CODES can be found in Geology: Sharon R. Allen and Jocelyn McPhie, ‘Products of neptunian eruptions’, Geology, July 2009, pp. 639-642 [DOI 10.1130/G30007A.1].

N.B. Not to be confused with Neptunism.

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Volcano research miscellany 7 May 2009

Posted by admin in Africa, current research, geoscience, Hawaii, Kilauea, Ol Doinyo Lengai, Pacific, submarine volcanism, Tanzania, United States.
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Various interesting bits and pieces of volcano-related research to report. Apologies for the lack of detail, but I’m pressed for time right now.

Ash evidence suggests impact of past eruptions underrated – a research team from the University of Oxford has studied the distribution of ash from the Chaitén eruption and concluded that the impact of past volcanic eruptions is likely to have been significantly underestimated, because so much ashfall is light (a few millimetres thickness) and is quickly lost from the areas affected. More on this at Science Daily, under the snappy headline Chaitén Volcano In Southern Chile: Historic Volcanic Eruptions Significantly Underestimated, Ash Fallout Analysis Shows.

Origins of Ol Doinyo Lengai’s weird lavas probed – the unique carbonatite lavas of Ol Doinyo Lengai volcano in Tanzania are produced by a very low degree of partial melting of the upper mantle minerals, concludes research to be published shortly in Nature by U.S. and French scientists. Science magazine’s ScienceNOW (caps lock stuck down?) news service also has an article on this, bafflingly entitled Volcanic Fish Out of Water.

Thriving ecosystem supported by NW-Rota 1 – scientists who have just returned from filming and studying the deep undersea volcano NW-Rota 1 report that the active volcano nourishes a rich and thriving biological community including shrimps, crabs, limpets and barnacles, some of which are new species. National Geographic News has some pictures.

Gentle, easy-going Kilauea has a dangerous side – between 1000 and 1600 years ago Kilauea, known today for its gentle tourist-friendly lava flows, chucked rocks 16 or 17 kilometres during powerful explosive eruptions.

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New Zealand undersea volcanism at the Eruptions blog 12 March 2009

Posted by admin in current research, geoscience, New Zealand, submarine volcanism.
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Dr Klemetti has an interesting post at his Eruptions blog today on undersea volcanism in the Kermadec Arc, north of New Zealand. A study by the University of Southampton and the University of Washington found evidence of a high level of volcanic activity in this area, with the delightfully-named Rumble III volcano having apparently filled in its crater and lost 100m in height since 2007. Eruptions has all the information and relevant links: Volcanoes old and new in New Zealand.

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