Project Details
Projekt
Molecular-life signatures and organic-matter transformations at the temperature limit of life, IODP Exp. 370
Applicant
Dr. Florence Schubotz
Subject Area
Palaeontology
Mineralogy, Petrology and Geochemistry
Mineralogy, Petrology and Geochemistry
Term
from 2018 to 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 408178672
Exp. 370 was implemented to explore the upper temperature of life of the deep biosphere off Cape Muroto, Nankai Trough, Japan, a site with an extraordinarily high heat flow and where temperatures at the sediment-basement interface are expected to reach the currently known temperature limit of life at around 120°C. These are also temperatures where catagenesis, the thermal breakdown of organic material to liquid and gaseous hydrocarbons, occurs. Through the catagenic reactions it is assumed that the more labile and potentially more oxidized organic material becomes bioavailabe and this has been proposed to directly feed indigenous microbial communities at high temperatures, providing a link between these abiotic and biotic zones. The overarching research questions in this project are: What is the extent of the deep biosphere close to the temperature limit of life? How is life adapted to high temperatures in an energy-limited habitat? What are the bio-available compounds that are released from the kerogens in sediments with low organic-carbon content and what are the substrates that fuel microbial subseafloor systems close to the temperature limit of life? This proposal intends to implement a comprehensive geochemical approach that will include the quantitative and qualitative downcore analysis of molecular life detection markers such as intact polar lipids and respiratory quinones with ultra-sensitive mass spectrometric techniques. These investigations will be closely coupled to a detailed characterization of the soluble and insoluble organic matter (kerogen). Using elemental, mass spectrometric, spectroscopic and pyrolytic techniques, the quality and bioavailabilty of the kerogen-bound organic matter will be assessed. In addition, the potential for organic substrate generation that may feed the indigenous microbial communities will be tested via hydrous pyrolysis laboratory experiments. This research is directly relevant to fundamental questions of current deep biosphere research and promises to significantly advance our understanding of the extent of the deep subsurface biosphere and the factors which may ultimately limit deeply buried life.
DFG Programme
Infrastructure Priority Programmes
