Microbiology of the Chicxulub Impact Crater

The deep subsurface is recognised to be an environment that supports a large and diverse microbial biosphere, and yet we still know very little about how microorganisms grow in this environment, what their spatial diversity is and how this diversity is controlled by subsurface geochemical conditions. Previous research has primarily focused on deep-ocean sediments. Work in these environments has shown that geochemical interfaces are important for determining the diversity of the subsurface biosphere. Little is known about how the subsurface biosphere in marine environments compares to that in continental subsurface environments.

Our laboratory will acquire core samples collected from the peak ring of the 66 million-year old Chicxulub impact structure buried beneath the Gulf of Mexico in April-May 2016 during IODP Expedition 364. This end-Cretaceous impact structure is hypothesised to have been responsible for causing the extinction of the dinosaurs and ~75% of all other life at this time. The drill core will be retrieved with microbiological contamination control to ~1.5 km depth. Thus, the drill core offers the opportunity to investigate the subsurface microbiology of a continental site and also how the microbial diversity relates to a unique, but well-defined subsurface lithologic sequence. In this project we propose to use these cores to gain new insights into the diversity of microorganisms in the subsurface. In this project we will: 1) Quantify the biomass of microorganisms through the core and correlate it to the lithologies to understand how microbial life in the continental deep subsurface is influenced by lithology, 2) Specifically investigate how microbial abundance and diversity is correlated to impact lithologies to understand how impacts can disrupt the deep subsurface biosphere, 3) Culture and use '-omics' methods such as metagenomics to understand how the functional capabilities and metabolisms of organisms correlate to the environment and lithology through the core to gain a better understanding of microbial biogeochemical processes in the deep subsurface in general and specifically in an impact crater, 4) Use the above data to understand more generally how life recolonises impact craters and how craters might provide a habitat for life despite otherwise catastrophic effects on large surface dwelling life.

Who will benefit from this research?

Many groups will benefit from this research including:
1) The international community of researchers interested in understanding the deep subsurface biosphere and the conditions under which it originated.
2) The astrobiology community interested in habitats for life in extreme environments and how planetary geological history is linked to biological evolution.
3) Drillers and other contractors interested in understanding better how to drill different types of continental crust and how to incorporate the demands of contamination control into drilling operations.
4) Water and soils quality scientists who want to know more about how subsurface microbial communities become established and how these communities are correlated to subsurface conditions.
5) The general public who have a strong interest in understanding life in extreme environments, how asteroid and comet impacts might affect the biosphere and whether the study of life in the deep subsurface might tell us something about the possibilities for life elsewhere.

How will they benefit from this research?

1) Research conducted on the core material will provide new insights into the present deep biosphere. These groups will gain knowledge of this information through peer-reviewed papers, through public outreach and many outlets such as the IODP web site through which this information will be disseminated.
2) Since this is an international project involving then all of these groups will gain considerably from the large amount of information to be generated. This information will be available in the UK as we have made a commitment to be part of this project.
3) The contamination control requirements for the project will mean that we must liaise with drillers prior to and during the project and this will mean that expertise will be passed to them directly which can be used in future projects.

What will be done to ensure that they have the opportunity to benefit from this research?

1) The project is international and organised under the auspices of IODP. Workshops at IODP will provide information both for scientists and the media.
2) Peer-reviewed papers will be one primary means by which this data will enter into the public domain and become available to the wider community
3) The IODP web pages are used to disseminate information about IODP projects and this route will be used to provide information on the project and data once IODP has agreed to it being released to public domain.