Underwater volcano as an ore deposit

Researchers are drilling at the Mediterranean bottom

Exposure of Rockdrill 1 in front of Panarea during the research cruise M73 / 2. In the background right the volcano Stromboli. © S. Petersen, IFM-GEOMAR
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An international research team has for the first time investigated the ore deposits on the seabed north of Sicily. Using a special drill, the scientists succeeded in obtaining samples of massive ores with a thickness of at least five meters at an underwater volcano at 630 meters of water depth. These contain, among other things, iron, copper, zinc, lead and silver.

The expedition headed by the Kiel Leibniz Institute for Marine Sciences (IFM-GEOMAR) aimed to investigate the links between reservoir formation, water circulation in the seabed and microorganisms at warm Tyrrhenian Sea springs. The tool used was a drilling rig from the British Geological Survey. The "Rockdrill 1" is able to drill up to five meter long rock samples in one go.

Interface of tectonic plates

The study area lies between Naples and Sicily, right on the border between the African and the European tectonic plate. Here are not only the known volcanoes of the region, such as Stromboli or Vulcano, but also a number of submarine volcanic structures. On some of these volcanoes occur due to the contact of hot rock with sea water on ore deposits that have been barely studied.

Massive sulphide core from a depth of approx. 3 m below the seafloor. © S. Petersen, IFM-GEOMAR

"The composition of the mineralization shows us that there were hot, metal-rich solutions in the subsoil, even if these no longer emerge directly at the bottom of the sea, " says Sven Petersen from IFM-GEOMAR, chief scientist on the research vessel Meteor. In the vicinity of the exit point, however, unusual communities of microorganisms and higher organisms are found, which receive the necessary nutrients - such as hydrogen sulfide - from the rising warm solutions.

"The quantities of ore known to date are much too small to be economically interesting (only about ten thousand tons). However, during our drilling we did not reach the limits of mineralization, either to the sides or to the depths. So it's likely there's more ore left. However, further investigations and deeper drilling are needed to determine the potential. "Petersen continues. display

Interaction between magmatism and seawater

In addition to the exploration of the ore deposits, other very interesting rocks and sediments in the area of ​​the islands of Stromboli and Panarea were drilled on this expedition, which give clear indications of an interaction between magmatism and seawater. Various mineral formations indicate complex rock formation processes underground.

"In the contact between the hot magma and the sea water, there are intensive interactions that influence the rock composition, " Petersen explains the results of the meteor shower. And further: "As the magma cools in the underground, hot solutions are released that react chemically with the superimposed rocks. The original minerals are converted into new ones. Even if the solutions are no longer circulating through the rock, conclusions about the conditions of education can be drawn from the study of these new minerals. "

(idw - Leibniz Institute for Marine Sciences, 11.09.2007 - DLO)