Origins of extinction
Mérida, Yucatán (March 11, 2021).- “Studies carried out in the Chicxulub crater confirm that an asteroid was what caused the extinction of the dinosaurs”, said Jaime Urrutia Fucugauchi, a researcher at the UNAM Institute of Geophysics.
The nature and origin of the bolide have been analyzed from studies on the sequence in the crater and on the impact sequences at different sites. The ejecta layer has a global distribution and anomalies of iridium and elements of the platinum group indicate the presence of material from the asteroid, reports a bulletin.
“The evidence supports more that it is an asteroid. There are data on mineralogy, geochemistry, isotopes and physical properties in the Chicxulub ejecta, in the crater and nearby and distal locations, and even reports of possible fragments – very small – of the body that impacted, which correspond to a chondritic asteroid” commented the also member of the UNAM Governing Board.
Since the theory was proposed in the ’80s that the impact of a meteorite caused changes in the climate and environment leading to the extinction of dinosaurs and around 76% of organisms in oceans and continents, the question has been raised what its nature would be: a comet or an asteroid, said the member of El Colegio Nacional.
With the passage of time, multiple studies were carried out reviewing proposals, among them that it could not be only one impact, but several, for which the sequences were reviewed and craters with similar ages were searched.
By analyzing the layers of impact material in Chicxulub and in the ejecta, the results eliminated the possibility that they were multiple.
It has also been proposed that it was not an impact by a celestial object, but a volcanic eruption of great magnitude, which was also reviewed by geophysicists; the data also rules it out.
Until now, the researcher specified, the studies in the crater, the perforations, the impact material and the numerical models support that it was a chondritic-type asteroid; that is, objects formed in the initial stages of the origin of the solar system, which contain inclusions of calcium-aluminum and sub-millimeter spherules of compositions and textures similar to igneous rocks.
These melted at high temperatures and cooled very quickly in space.
A few years ago, he detailed, it was proposed that the fireball that formed the Chicxulub crater came from a collision in the asteroid belt between Mars and Jupiter, which formed the Baptistina group.
Due to this collision, several asteroid fragments entered orbits that cross the inner planets and eventually one collided with the moon and another with Earth, forming the Ticho and Chicxulub craters.
The study is interesting, but subsequent work indicated inconsistencies in the ages and characteristics of the Baptistina group.
“The possibility of a comet is not new, what this recent publication adds is the analysis of the dynamics of long-period comets, the interactions in the planetary system and the analysis of the frequency of these events,” said Jaime Urrutia to refer to the proposal that the object causing the cataclysm was a comet from the Oort Cloud.
The interest in Chicxulub is broad and interdisciplinary, which is reflected in the various groups of geophysics, planetary sciences and numerical models that review the structure, dynamics and formation of the crater, deformation, reaction forms of the impacted area and the fragmentation and ejection of materials from the lower cortex.
Studies are also carried out on the effects of the impact on the climate and environment, relationships with extinctions and their effect on groups of dinosaurs, ammonites and other organisms in seas and continents, macroevolution and the appearance of new species.
Recent studies in molecular biology and genomics contribute to deciphering the effects of the impact on evolutionary changes at the Cretaceous / Paleogene border.
Investigations continue on the fireball that caused the extinction of the dinosaurs.
Since the beginning of research, in the 80’s, various groups studied the frequency of impacts and the nature of impactor bodies.
The studies include those carried out in the cores of the Chicxulub drilling programs, which have documented relatively low concentrations of the impactor body in the breccias and molten rock.
These studies are being resumed in the cores of marine drilling in the ring of peaks, the first results of which are being reported.