Expedition 364 Chicxulub: Drilling the K-Pg Impact Crater

Lead Research Organisation: Imperial College London
Department Name: Earth Science and Engineering

Abstract

The Chicxulub impact crater, Mexico, is unique. It is the only known terrestrial impact structure that has been directly linked to a mass extinction event, and the only terrestrial impact with a global ejecta layer. Of the three largest impact structures on Earth, Chicxulub is the best preserved. Chicxulub is also the only known terrestrial impact structure with an intact, unequivocal topographic "peak ring". Chicxulub's role in the K-Pg mass extinction and its exceptional state of preservation make it an important natural laboratory for the study of both large impact crater formation on Earth and other planets, and the effects of large impacts on the Earth's environment and ecology. Our understanding of the impact process is far from complete and, despite over 30 years of intense debate, we are still striving to answer the question as to why this impact was so catastrophic.

Expedition 364 is the first drill hole into an intact topographic peak ring, and the first to penetrate the offshore portion of the Chicxulub crater. Peak rings are a ring of hills that protrude through the crater floor within large impact basins on the terrestrial planets, and there is no consensual agreement on either their formational mechanism or the nature of the rocks that form them. Geophysical data indicate that the peak ring at Chicxulub is formed from rocks that have a low velocity and density, and one explanation for this is that they are highly fractured and porous. Immediately after impact the peak ring was submerged under water, and located adjacent to a thick pool of hot melt rocks. Hence, we would expect intense hydrothermal activity within the peak ring. This activity may have provided a niche for exotic life forms, in a similar way that hydrothermal vent systems do in the oceans. Drilling the peak ring will determine the origin, lithology, and physical state of the rocks that form it, allow us to distinguish between competing models of peak-ring formation, as well as document the hydrothermal systems and any associated microbiology. Immediately after impact the ocean is, locally, likely to have been sterile. We will use core through the post-impact sediments to examine the recolonization of the ocean, including: what biota came back first (benthic, dinoflagellates, specialists vs generalists), and how long did it take to return to normal conditions?

The proposed drilling directly contributes to IODP goals in the: Deep Biosphere and the Subseafloor Ocean and Environmental Change, Processes and Effects, in particular the environmental and biological perturbations caused by Chicxulub.

Planned Impact

One of the roles of co-chief scientists is to promote NERC activities and its support for UK IODP involvement. Expedition 364 has already received significant media attention, and several companies have expressed an interest in making a documentary about the drilling. ESO and the two co-chiefs have entered into a contract with Barcroft Productions to make a fly-on-the-wall documentary showing both the offshore and onshore activities.

The publication procedure from IODP Expeditions is designed to gain maximum impact and timeliness. In addition to expedition reports, the science party are mandated to publish the results of their work within a strict time limit. One of the roles of co-chief scientists is to ensure publication at the highest possible level of quality and visibility.

Other beneficiaries include:

1. The local population and next generation of young scientists in the Yucatan;
2. The mining and mineral exploration industries;
3. The insurance industry, regarding the financial consequences of impacts;
4. The general public.

1. The Yucatan government has invested significant funds in a new museum in the centre of Merida, Gran Museo del Mundo Maya (http://www.granmuseodelmundomaya.com), and a large Science Park just outside the city. We have met with the Director of Education for the Yucatan, as well as the Museum curators, and they propose to use the Chicxulub drilling for both tourism and educational purposes, including placing an exhibit with a replica drill core at one of these two locations.

2. The two other known terrestrial craters of a similar size to Chicxulub (Sudbury and Vredefort) are associated with significant mineral deposits. The peak ring may be rich in PGEs (or some other resource) and be of interest for future exploration.

3. The insurance industry has shown increasing support for studies of natural hazards, and impacts specifically, especially following the Chelyabinsk event in 2013 when videos of the meteor entry went viral. Simulations of impacts of various sizes provide critical user input into risk analysis studies leading, for example, to the development of new risk assessment tools for future impacts.

4. The public will benefit from outreach activities in Mexico, the UK and elsewhere (there are 30 science party members from 11 different countries). We propose to capitalize on the public's interest in the "death of the dinosaurs".

Publications

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Collins GS (2020) A steeply-inclined trajectory for the Chicxulub impact. in Nature communications

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Lowery C (2019) Ocean Drilling Perspectives on Meteorite Impacts in Oceanography

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Gulick SPS (2019) The first day of the Cenozoic. in Proceedings of the National Academy of Sciences of the United States of America

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Lyons SL (2020) Organic matter from the Chicxulub crater exacerbated the K-Pg impact winter. in Proceedings of the National Academy of Sciences of the United States of America

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Morgan JV (2016) The formation of peak rings in large impact craters. in Science (New York, N.Y.)

 
Description Improved constraints on sulphur released from the sedimentary rocks at the impact site, with implications that the Earth's surface suffered sub-freezing temperatures for at least 1 year after impact

Improved constraints on the amount of soot that was generated at the impact site and then circled the globe in a dust cloud, which would have initiated global darkening
Exploitation Route They will be used as an input to GLOBAL CLIMATE MODELS, that predict temperatures on Earth and in the oceans after impact.
Sectors Education,Environment

 
Title Dataset for "A steeply-inclined trajectory for the Chicxulub impact" 
Description Data files for 5 timesteps from each simulation. File name convention is A<angle>_v<velocity>_t<time>.npz where time is in seconds (or the string "final"). Each file contains several cell-based fields (pressure, temperature, specific internal energy, density), tracer fields (peak tracer pressure, x,y,z locations) and grid information (nodal and cell-centred coordinates). For an example of how to access all that information, see the "Timestep" class at the top of the "plot_frame.py" python script. Python script "plot_frame.py" will create a figure similar to the panels in Figures 2 and 3 in the paper. Use the flags -a, -V and -t to set the desired impact angle, impact velocity and time. iSALE3D input files for the 8 simulations can be found in inputfiles.tgz Postprocessing python scripts can be found in postprocessing.tgz 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://zenodo.org/record/3667832
 
Title Dataset for "A steeply-inclined trajectory for the Chicxulub impact" 
Description Data files for 5 timesteps from each simulation. File name convention is A<angle>_v<velocity>_t<time>.npz where time is in seconds (or the string "final"). Each file contains several cell-based fields (pressure, temperature, specific internal energy, density), tracer fields (peak tracer pressure, x,y,z locations) and grid information (nodal and cell-centred coordinates). For an example of how to access all that information, see the "Timestep" class at the top of the "plot_frame.py" python script. Python script "plot_frame.py" will create a figure similar to the panels in Figures 2 and 3 in the paper. Use the flags -a, -V and -t to set the desired impact angle, impact velocity and time. iSALE3D input files for the 8 simulations can be found in inputfiles.tgz Postprocessing python scripts can be found in postprocessing.tgz 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL https://zenodo.org/record/3667833
 
Description Mapping of Chicxulub crater features 
Organisation University of Texas
Country United States 
Sector Academic/University 
PI Contribution Sharing of geophysical inversion codes developed at Imperial to be used to map crater features
Collaborator Contribution Performed the geophysical inversions
Impact Inversions are in progress. They were presented at AGU in 2017, but have not been written up yet.
Start Year 2017
 
Description 2017 AGU Fall Meeting Frontiers of Geophysics Lecture - Chicxulub: The End of an Era. The 2017 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact 2017 AGU Fall Meeting Frontiers of Geophysics Lecture - Chicxulub: The End of an Era. This was one of a few key note lectures at AGU that was filmed and broadcast live. The attendance at AGU was 22000
Year(s) Of Engagement Activity 2017
URL https://www.youtube.com/watch?v=xCJEU6PBd3M
 
Description BBC Documentary, The day the dinosaurs died 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact The original documentary was shown on BBC2. Versions of the documentary have now been shown in France, Germany, the USA, Japan, Australia and elsewhere. The documentary showed the Expedition 364 science team during the offshore drilling and at at the onshore party in Bremen.
Year(s) Of Engagement Activity 2017
URL https://www.youtube.com/watch?v=Id-M1lerGDQ
 
Description Exhibition at the Imperial Festival 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact We had a stand that exhibited three recent IODP drilling exhibitions, that included a large rubber map on the floor of all the expeditions, and a blow up JR vessel (loaned from the US). Children were encouraged to put on survival suits. The exhibit was inundated with visitors for two solid days.
Year(s) Of Engagement Activity 2019
URL https://www.imperial.ac.uk/festival/
 
Description PESGB lecturer Geoliteracy tour 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact I was the speaker for the PESGB lecture series and have talks in London, Birmingham and Aberdeen.
Year(s) Of Engagement Activity 2018
URL https://www.pesgb.org.uk/events/london-stoneley-lecture-part-pesgb-geoliteracy-tour-2018/
 
Description Talk to teachers for the Geological Society Education 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact The GEA runs annual events, inviting science teachers to come and find out about geology. The purpose is to promote the teaching of geology in schools, and encourage schools to recommend geology as a potential undergraduate degree course to their pupils. I gave the key note talk at one of these events.
Year(s) Of Engagement Activity 2017
URL https://www.geolsoc.org.uk/education