Active Hydrothermal System within the Chicxulub crater helped life recovery after the impact of the Dino-Killing Asteroid
VUB-researchers help uncover the reasons why it happend so fast
About 66 million years ago, an asteroid slammed into the planet, wiping out all non-avian dinosaurs and about 70 percent of all marine species. The huge crater formed in the Gulf of Mexico functioned as a cradle for recovery of marine life enriching the overlying ocean for at least 700,000 years, according to research published today in Nature Communications.
An international team of scientists, including VUB-AMGC’ers (Vrije Universiteit Brussel - Large research group: Archaeology, Environmental Changes & Geo-Chemistry) Professors Steven Goderis and Philippe Claeys have discovered that a hydrothermal system created by the asteroid impact have helped marine life flourish at the impact site by generating and circulating abundant nutrients in the crater environment.
Directly after the asteroid impact, the Gulf of Mexico region records a booming ecological recovery process that differs from the slower pace observed in global oceans. This recovery is most likely due to the continuous hydrothermal activity, within the freshly formed crater that created a unique marine environment,” said the study’s lead author Dr. Honami Sato, an assistant professor at Japan’s Kyushu University.
The study is the latest discovery to come from research on the 829 meters of core retrieved by a joint IODP (International Ocean Discovery Program) – ICDP (International Continental Scientific Drilling Program) project in 2016 within the Chicxulub crater by the international team of researchers.
Previous research already determined that life returned to the site of the crater within a matter of years. This study presents new evidence that a hydrothermal system, generated by the large melt sheet buried beneath the seafloor within the crater formed by the asteroid impact actively sustained this ecological recovery for the first hundreds of thousands of years of the Cenozoic.
The research hinges on a chemical element called osmium. A particular ratio of osmium isotopes is associated with asteroid materials that differs significantly from that of the Earth crust. The researchers found evidence that submarine hydrothermal activity continuously released this unique asteroidal osmium, initially buried kilometers beneath the Chicxulub crater by the collision.
As hot water in contact with this melt sheet, moved beneath the sea floor and up toward the surfacein entrained minute traces of the asteroid. As the hydrothermal fluid cooled over time, the asteroid traces exited the water and precipitated into sediment. The researchers analyzed the early Cenozoic sediments, in the IODP-ICDP core samples, and used it to determine the extent of the hydrothermal system and how long the enrichment of osmium lasted: at least 700 000 years.
The study also demonstrated that as the hydrothermal system ceased releasing asteroidal osmium marine life within the crater site changed: during extended period of osmium release by the hydrothermal the marine plankton was characteristic of high-nutrient environments. When the release of asteroidal osmium was exhausted and the marine osmiun returned to normal pre-impact levels, the plankton switched to organisms characteristic of low-nutrient environments. This finding indicates that the regional ecosystem was no longer being sustained by the nutrients from the hydrothermal system being released into the overlying ocean. However, beneath the seafloor the hydrothermal system continued to persist for many millions of years; most likely it just became ever more deeply buried by millions of years of sedimentation.
“This study reveals that impact cratering events, while primarily destructive, can in some cases also lead to significant hydrothermal activity,” said co-author Steven Goderis, a research professor at AMGC (Large research group: Archaeology, Environmental Changes & Geo-Chemistry) at the Vrije Universiteit Brussel, in Belgium. “In the case of Chicxulub, this process played a vital role in the rapid recovery of marine ecosystems.” Philippe Claeys, a 40-year veteran of the dinosaur extinction – asteroid impact theory, emphasizes the fact that if meteorite impacts cause mass extinction, the formation of large craters also sustains new life forms. A key point to understand early life on Earth and an indicator that large impact structures could be the place to seek traces of life on other planets.
The science team included a multidisciplinary group of researchers from Kyushu University; Vrije Universiteit Brussel, Belgium; the University of Texas Jackson School of Geosciences; the Japan Agency for Marine-Earth Science and Technology; Institute of Science Tokyo; Universidad de Zaragoza, Zaragoza, Spain; Universitat de Barcelona, Barcelona, Spain; and Imperial College London.
More information:
Steven Goderis: Steven.Goderis@vub.be
Philippe Claeys: phclaeys@vub.be
