T-Limit of the Deep Biosphere off Muroto: IODP Expedition 370

One of the key scientific objectives in studies of deep life and carbon is to understand environmental factors that constrain population, activity, diversity and ecological function of microbial communities, and the extent of habitable zones in Earth’s interior.

To better constrain the temperature limit of life in the deep biosphere, the International Ocean Discovery Program (IODP) is preparing Expedition 370 “T-Limit of the Deep Biosphere off Muroto (T-Limit)” with the Japanese drilling vessel Chikyu to revisit Ocean Drilling Program (ODP) Site 1174 in the Nankai Trough subduction zone off Cape Muroto, Japan (10 September - 10 November 2016).

Because of the high heat flow in this part of the Nankai Trough (4731 m water depth), temperatures are likely ~130°C at the sediment/basement interface (1210 mbsf). This makes the site an ideal target for in-depth examination of subseafloor microbial life close to its putative upper temperature limit. ODP Leg 190 has already shown that cell concentrations drop abruptly at sediment depths around 800 mbsf. Exp. 370 now returns to investigate this putative biotic-abiotic transition with technologies that have advanced tremendously over the past 16 years. The expedition's scientists aim to study diversity, activity, and biomass of microbial communities at the biotic fringe as well as the controlling environmental factors. In order to fully exploit the available technologies, the scientific work program onboard Chikyu will be complemented by simultaneous analytical work in the ultra-clean room facilities of the Kochi Core Center (KCC), which is located within reach of a helicopter shuttle for transportation of freshly cored samples. After drilling, multiple-temperature sensors will be installed into the borehole, allowing ~1 year monitoring of formation temperature in situ. For more information see the expedition homepage: http://www.jamstec.go.jp/chikyu/e/exp370/

The International Ocean Discovery Program (IODP) Expedition 370 Scientific Prospectus, T-Limit of the Deep Biosphere off Muroto (T-Limit): Deciphering factors that constrain the extent of the deep biosphere in a subduction zone, is now published on the IODP website (doi:10.14379/iodp.sp.370.2016). 

 

Further Reading

DCO Research The Seas Are Alive with the Sound of Methane

Researchers adapted sonar equipment to quantify the amount of methane bubbling up from the floor of…

DCO ABOVE Expedition
DCO Highlights DCO ABOVE Expedition: Updates from the Field

DCO ABOVE (Aerial-based Observations of Volcanic Emissions) is the second part of a DCO-funded…

 Solving Subduction Zone ‘Headaches’
DCO Research New Approach to Solving Subduction Zone ‘Headaches’

A new way of determining the amount of carbon entering a subduction zone, where an oceanic plate…

more viruses revealed below the seafloor
DCO Research Many More Viruses Revealed Below the Seafloor

Researchers at JAMSTEC have developed a new method to extract viruses from deep-sea sediments,…

Back to top