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Drilling for Sub-Seafloor Life

The Japanese deep-drilling vessel DV Chikyu can core up to 4000 metres below the seabed and in areas where there is a potential danger of striking oil or gas. Photo courtesy of the Japan Agency for Marine–Earth Science and Technology

The Japanese deep-drilling vessel DV Chikyu can core up to 4000 metres below the seabed and in areas where there is a potential danger of striking oil or gas. Photo courtesy of the Japan Agency for Marine–Earth Science and Technology

By Chris Yeats

Extreme sub-sea temperatures, noxious fumes and broken drilling rods made life difficult onboard a scientific expedition that set out to sample life deep beneath the sea.

The full text of this article can be purchased from Informit.

The International Ocean Discovery Program (IODP) is an international marine research collaboration that employs drill ships to recover samples of sediment, rock, fluids and living organisms from deep beneath the seafloor. In 2010 I was a member of IODP Leg 331, which drilled five sites at the Iheya North hydrothermal field in the Central Okinawa Trough back arc basin south of Japan.

Leg 331 was unusual for a couple of reasons. First, the 34-day expedition aboard the drill ship DV Chikyu was significantly shorter than a typical 2-month IODP expedition. Second, and more significantly, it was the first IODP expedition, and still one of only a handful of cruises, to focus principally on biology rather than geology.

The impact of this focus on the scientific party was profound: membership was dominated by microbiologists, biochemists and fluid chemists, for whom the recovered core was a means not an end. Consequently, logging of the 312 metres of drill core recovered during the expedition was left to a small team of three to four geologists, most of whom had been attracted to the cruise by the possibility of drilling metal-rich massive sulphides – but more on that later.

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