Additional Report for Mid-Cayman Spreading Center

Mid-Cayman Spreading Center

Cayman Trough, Caribbean Sea

17.90°N, 81.77°W; depth -4,960 m

The Cayman Trough, where the seafloor of the Caribbean is rifting apart, harbors the world's deepest chain of undersea volcanoes,. The Mid-Cayman Spreading Centre (MCSC), the geological name for the chain of volcanoes ~ 80-110 km long that runs N-S across the Cayman Trough in the W Caribbean Sea, S of Cuba and Jamaica and close to the Cayman Islands, is an ultraslow-spreading ridge with a rate of less than 20 mm per year (ultraslow-spreading ridges make up more than 20% of the world's mid-ocean ridges). The MCSC is connected to a group of faults that allow the Caribbean plate to move relative to the North American plate. It has some of the deepest seafloor in a ridge setting, up to 6,500 m below sea level in places.


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06/2010 (BGVN 35:06) Expedition discovers deep undersea volcanic vents


Contents of Monthly Reports

All information contained in these reports is preliminary and subject to change.

06/2010 (BGVN 35:06) Expedition discovers deep undersea volcanic vents

According to a report in ScienceDaily on 12 April 2010, a scientific expedition from the United Kingdom National Oceanography Centre (NOC) discovered the world's deepest undersea volcanic vents, known as 'black smokers.' The vents, seen on 11 April, were located at a depth of 4,960 m in the Mid-Cayman Spreading Centre (MCSC), also known as the Mid-Cayman Rise Spreading Center (Thompson and others, 1980), of the Cayman Trough in the western Caribbean Sea (figure 1).

Figure 1. Bathymetric map showing plate tectonic configuration and location of the Mid-Cayman Spreading Center (MCSC) within the Cayman Trough, south of Cuba in the western Caribbean Sea. Modified from the Smithsonian's "This Dynamic Planet" interactive map.

Using remote deep-diving vehicles, the scientists found slender spires made of copper and iron ores on the seafloor, erupting water hot enough to melt lead, ~ 800 m deeper than anyone has seen before (figure 2). The deep-diving vehicles included Autosub6000, developed by engineers at the NOC for surveying; TOBI – Towed Ocean Bottom Instrument– towed behind the ship a few hundred meters above the seafloor, mapping it in detail with its sonar system and other instruments such as a magnetometer; HyBIS, developed by expedition member Bramley Murton and Berkshire-based engineering company Hydro-Lek Ltd. for filming. Instruments were remotely controlled from the Royal Research Ship (RRS) James Cook. Daily details of the expedition may be found on the RRS James Cook Voyage 44 website.

Figure 2. Photograph of a 'black smoker' vent erupting hot water at a depth of ~ 5,000 m on the ocean floor in the Cayman Trough, Caribbean Sea. Courtesy of NOC.

In addition to the scientists from NOC, the team aboard the ship included researchers from the University of Southampton's School of Ocean and Earth Science (SOES), University of Durham in the UK, the University of North Carolina Wilmington, and the University of Texas in the US, and the University of Bergen in Norway. Expedition members also worked with colleagues ashore at Woods Hole Oceanographic Institution and Duke University.

Reference. Thompson, G., Bryan, W.B., and Melson, W.G., 1980, Geological and geophysical investigation of the Mid-Cayman Rise Spreading Center: geochemical variation and petrogenesis of basalt glasses: The Journal of Geology, v. 88, no. 1, p. 41-55.

Information Contacts: ScienceDaily (URL: http://www.sciencedaily.com/); United Kingdom National Oceanography Centre (NOC), University of Southampton Waterfront Campus, European Way, Southampton SO14 3ZH, United Kingdom (URL: http://www.noc.soton.ac.uk/); RRS James Cook Voyage 44 (URL: http://www.thesearethevoyages.net/).