163-2 66 Million Years of Sustained Hydrothermal Convection at Chicxulub Crater

Session: Impact Cratering Processes Across the Solar System: In Memory of Dr. Bevan M. French

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Abstract:

The environment of the origins of life on Earth has long been associated with “warm little ponds”. Recently, impact craters have been under increasing investigation as viable sites for microbial evolution due to their potential to facilitate the generation of prebiotic chemistry. The Chicxulub impact structure, in particular, has evidence of an extant microbial community and signs of hydrothermal alteration. Additionally, it is the only crater on Earth with a well-preserved peak ring, making it suitable for investigations that can be transferred to other regions. The Chicxulub impact famously led to the end-Cretaceous mass extinction, and its post impact hydrothermal system has been suggested as a catalyst for the rapid recovery of life that ensued shortly after the event. Consequently, the system has been modelled numerous times to determine its lifetime and how it is linked to endolithic colonization. Adopting a different approach, we have utilized modern day properties at Chicxulub, acquired from IODP-ICDP 2016 drilling operations into the peak ring, in tandem with previous modelling studies and seismic data to create a new model for current hydrothermal convection within the crater. Radially distributed model geometry was largely informed by seismic surveys whereas properties were prescribed to major lithologic units based on measurements obtained from core samples and hydrocode simulations. The results suggest that hydrothermal fluid circulation is currently active within the subsurface of the crater, even though the initial heat generated has dissipated. Pre-impact sediments have been relocated to depths multiple kilometers beneath their origin and have also experienced increased permeability. In contrast, the adjacent granitic basement has been uplifted up to 10km and undergone shock metamorphism, thereby also increasing its permeability. These lithologic units provide ideal pathways for hydrothermal fluids to be transported and the low permeability of overlying melt rock and suevite limit fluid escape. Assisting in the longevity of the system is the fact that the lateral temperature distribution is no longer uniform, but rather elevated in the crater’s central region indicating that impacts can generate lasting thermal anomalies which can ultimately support microbial communities feeding off hydrothermal systems for an indefinite amount of time.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10747

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