Frequent fires struck Antarctica during the Age of Dinosaurs, 75 million years ago

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Paleontologists from Brazil and Chile reveal an important discovery about the past of the most inhospitable continent on Earth, Antarctica. Today covered in snow, in the past, however, the location was not like this. The research, led by Brazilian paleobotanist Dr. Joseline Manfroi, along with her collaborators, proves that Antarctica was disturbed by frequent forest fires that were directly associated with active volcanic episodes during the end of the Age of Dinosaurs, 75 million years ago.

The research was developed with paleontological samples collected on King George Island, in the Shetland Islands archipelago, on the Antarctic Peninsula, during scientific expeditions carried out by the Chilean Antarctic Institute (INACH) and the Brazilian Antarctic Program (Proantar). The first evidence of forest fire occurrence in Antarctica had already been proven by the same researcher in 2015, in a paper published in the journal Palaeogeography, Palaeoclimatology, Paleoecology, entitled The first report of a Campanian palaeo-wildfire in the West Antarctic Peninsula. In 2021, another study for Antarctica also presented more evidence on the issue.

The Antarctic continent, because it is considered the continent of extremes, is one of the environments that is increasingly arousing research interest for a better understanding. In addition to being the continent that presents the most unfavorable conditions for the development of terrestrial biodiversity today, due to its hostile abiotic factors (such as significant cold and wind intensity), it is also the continent that best preserves its environmental characteristics, being a true natural laboratory that brings together exceptional conditions for the development of basic and applied sciences research, which makes it especially interesting from a human perspective.

The scientific research with international collaboration between Brazil and Chile was funded by the National Council for Scientific and Technological Development - CNPq and developed with the collaboration of different institutions, including: the Chilean Antarctic Institute (INACH), the University of Vale do Rio dos Sinos (Unisinos), the University of Vale do Taquari (Univates), the Federal University of Rio Grande do Sul (Ufrgs), the University of São Paulo (USP) and the Brazilian Antarctic Program (Proantar), through the Floratar project.

Implications of the study

Through this research, it is known that southern environments, during the Cretaceous period, were also disturbed by the occurrence of forest fires, much more frequent than previously thought, which consumed vegetation partially or totally. The analysis of these fragments of carbonized plant fossils recovered in Cretaceous deposits in Antarctica, especially those recovered on King George Island, not only allowed the characterization of the vegetation that was burned, mainly composed of plant known as gymnosperms. It also allowed the diagnosis of the elements involved in the ignition of vegetation, thus enabling the reconstruction of a paleoenvironmental scenario that is easy to understand.

“The intense volcanism attested to in the Cretaceous, which comprises a large part of the rock layers in Antarctica, was also the driving force behind the forest fires that occurred during this same period. However, contrary to what one might imagine, it was not the flows of molten lava from active volcanism that consumed the vegetation, but rather the contact of the vegetation with the heated ash clouds, pyroclastic clouds, that were expelled by the volcanoes, which were preserved in the geological record through very fine volcanic sediments, such as volcanic tuffs. These heated ash clouds reached the forests, causing the onset of natural vegetation fires," comments the lead author, Dr. Joseline Manfroi.

“It can be said that, despite Antarctica being represented in modern times by its negative temperatures and 98% coverage of ice on its territory, throughout its geological history, its environments were once ablaze, attested by the plant fossils that demonstrate the occurrence of fires in vegetation. The action of fire on vegetation was frequent and shaped and disturbed the southern forests during the Cretaceous period, influencing the evolution and floristic biodiversity in these areas of the globe,” emphasizes the researcher.