The AUV ABYSS is waiting for its use on deck of the research vessel METEOR. Photo: Solvin Zankl

Image of the month: August 2017

Raw materials from the deep-sea

What does the submarine landscape look like? How much metal do mountains and the rocks at the bottom of our oceans contain? Is it possible to secure the global supply of raw materials with sustainable submarine mining? The Autonomous Underwater Vehicle AUV ABYSS is waiting for its use on deck of the research vessel METEOR to answer these and other questions.

The more scarce metallic raw materials become onshore, the closer raw material occurrence of the deep-sea moves in the center of the interest. Beside manganese nodules, cobalt crusts and sulphide muds, massive sulphides could potentially be extracted in the future. They form in so-called Mid-Ocean Ridges, where submarine plate boundaries meet and new seabed is formed by volcanic activity.

Massive sulphides originate from the interaction between cold sea water and hot volcanic rock in the subseafloor. The water is heated to a temperature of up to 400°C, reacts with the surrounding rock and dissolves the contained metals. Due to the heating, the density of the water changes, it rises fast to the seafloor. When this solution meets the cold sea water, the dissolved metals are deposited in form of chimney-like structures, so-called “Black Smokers”. However, only few of the known occurences are big enough and contain the right metal in order to be interesting for the mining. It is assumed that inactive deposits, which have already a complete cycle of formation, could be much bigger.

Because the seabed is largely unexplored and unmapped, only a few of these inactive deposits are known. Predictions of the global sulphide metal potential are currently based on exploration methods that will detect only active and therefore often young hydrothermal deposits. In the framework of the “Blue Mining”-Project, supported by the European Union, new technologies are being developed to find inactive deposits and to allow a more realistic estimate of the raw metal potential of an entire mid-ocean ridge segment.

One of these technologies was tested on the expedition M127 in 2016. The AUV ABYSS provides high-resolution maps with its multibeam echo sounder as well as other geophysical and geochemical sensors, in order to make  precise sampling of these occurrences possible.

More information:

http://www.geomar.de/zentrum/einrichtungen/tlz/

http://jpio-miningimpact.geomar.de/de

http://www.bluemining.eu/

 http://www.geomar.de/de/forschen/expeditionen/detailansicht/exp/completed/337923/

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The AUV ABYSS is pulled in. Photo: AUV-Team/GEOMAR

The AUV ABYSS is pulled in. Photo: AUV-Team/GEOMAR

A Black Smoker on the seafloor. Photo: ROV-Team/GEOMAR

A Black Smoker on the seafloor. Photo: ROV-Team/GEOMAR

Cross-section of an massive sulphide sample. Photo: GEOMAR

Cross-section of an massive sulphide sample. Photo: GEOMAR