An international scientific team involving Spanish micropaloantologists discovered a unique marine environment created by the impact of the Chicxulub asteroid, 66 million years ago.
Nature Communications magazine publishes the team’s discovery, headed by the Honami Sato Geochemistry (University of Kyūshū, Japan), and in which the micropalo-anthists Ignacio Arenillas, José Antonio Arz and Vicente Gilabert, of the Department of Earth-Iuca Sciences of the University of Zaragoza (Spain), among other authors are.
66 million years ago, between the Cretaceous and Paleogen periods, the asteroid Chicxulub hit the coast of the Yucatan Peninsula, in Mexico, causing intense environmental disturbances and the extinction of 76% of marine life, reports the University of Zaragoza.
Previous studies showed that the marine ecosystem inside the crater took only 30,000 years to recover and although an explanation for this speed had not yet been found, the work published now offers a plausible reason.
The investigations carried out that the former Gulf of Mexico became, after the impact of Chicxulub, a semi -in -law under intense hydrothermal activity linked to the important fractures of the land generated by the collision.
As a consequence, hot fluids rich in dissolved metal nutrients that stimulated the growth of bacterial phytoplankton and the rapid recovery of the ecosystem.
The identification of a region with hydrothermal sources was based on the behavior of the relationship of the osmium isotopes in rocks deposited throughout the first three million years after the impact.
These rocks were collected in a drilling carried out by an international consortium inside the Chicxulub crater and in four Mexican locations that surround the same.
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Asteroid would have contributed the recovery of marine ecosystems
The vaporization of the Chicxulub asteroid contributed large amounts of Osmio isotopes of the so -called 188os causing that, during the first 200,000 years after the impact, the ocean sediments will globally register exceptionally low values of isotopos 187os and 188os. After this period, the oceanic sediments contain values similar to those measured at the end of the Cretaceous.
However, the new study demonstrates that in the Gulf of Mexico this situation back to normal was delayed up to 700,000 years, thus revealing the existence at the beginning of the paleoge of underwater hydrothermal sources of a colossal size that contributed continuously fluids loaded in 188os and in dissolved heavy metals, now recorded as geochemical anomalies in the rocks analyzed.
In this study, the Biocronology Team of the University of Zaragoza was responsible for the micropaloantological analysis of planktonic foraminifers, a group of protozoa of the marine plankton that left abundant fossil remains.
The high -resolution study provided a detailed age model that was used to assign a precise age to each of the geochemical samples analyzed in Japan.
The precise temporal control allowed faithfully to rebuild the changes in the relationship of the isotopes, in the content of heavy metals or in the communities of phytoplankton and zooplankton that inhabited the Gulf of Mexico at the beginning of the paleogen.
In addition, the temporal evolution of the relative abundances of the plankton groups analyzed indicates the existence of a stage in which the surface layer of the ocean in this region contained large amounts of dissolved nutrients (eutrophic).
Significantly, this stage with an abundance of plankton adapted to eutrophic conditions has a duration similar to that of the interval with anomalous values of 187os/188os, thus suggesting a cause-effect relationship.
The new publication demonstrates that, paradoxically, the impact of Chicxulub was not only the cause of the mass extinction of the Cretaceous-Paleogen limit, but also contributed to the recovery of the tented marine ecosystems of the Gulf of Mexico by creating an extensive field of hydrothermal sources that does not have equivalent in the current oceans.
Researchers hope to carry out similar studies in regions farthest from the Chicxulub crater (such as the Caribbean Sea or the Pacific), with the aim of clarifying the recovery patterns of oceanic ecosystems on a global scale and determining the factors that regulated them.
With EFE information
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