Paleontology & Fossils

New data suggests that numerous fires raged in Antarctica 75 million years ago.

An important discovery about the past of Antarctica, the planet’s most inhospitable continent, has been made by paleontologists from Brazil and Chile. Currently covered in snow, the location was not like this in the past. The study, which was led by Brazilian paleobotanist Dr. Joseline Manfroi and her colleagues, demonstrates that active volcanic events at the end of the dinosaur era, 75 million years ago, were directly linked to frequent forest fires that disturbed Antarctica.

Paleontological samples from the Chilean Antarctic Institute (INACH) and the Brazilian Antarctic Program (Proantar) scientific expeditions on King George Island in the Shetland Islands archipelago on the Antarctic Peninsula were used in the research.

In a 2015 paper titled “The first report of a Campanian palaeo-wildfire in the West Antarctic Peninsula,” which was published in the journal Palaeogeography, Palaeoclimatology, and Paleoecology, the same researcher provided the initial proof of the existence of forest fires in Antarctica. In 2021, a second Antarctica study provided additional evidence on the subject.

New evidence,

however, demonstrates that Antarctica was effectively on fire during the Cretaceous period, with frequent forest fires, according to the study conducted by Dr. Joseline and her collaborators while she was a postdoctoral researcher at the Chilean Antarctic Institute. Additionally, these fires were linked to the period’s active volcanism.

The brand-new piece, titled “Antarctica ablaze: The evidence for this significant discovery,” “Paleo-wildfires events associated with volcanic deposits in the Antarctic Peninsula during the late Cretaceous,” was published on April 14 in the journal Frontiers in Earth Science.

The study’s authors claim that understanding global environmental change is one of the greatest obstacles. As a result, it is of the utmost importance to create scenarios that make it easier to comprehend the environmental evolution of the world’s most diverse environments.

“What’s more, this development goes beyond the ongoing indications of unsettling influences in the conditions; however, it is likewise important to focus on examinations that address a more extensive fleeting scale. As a result, Joseline explains, “the fundamental tools for the construction of scenarios and models that enable a better understanding of terrestrial dynamics and assist in the conservation of current biota are characterizing and understanding past environments of the Earth, the paleoenvironments, and their disturbing agents (such as fire).”

One of the environments that is increasingly attracting research interest for a better understanding is the Antarctic continent, which is known as the continent of extremes. As a true natural laboratory that brings together exceptional conditions for the development of basic and applied science research, it is especially interesting from a human perspective. In addition to being the continent that presents the most unfavorable conditions for the development of terrestrial biodiversity at the present time due to its hostile abiotic factors (such as significant cold and wind intensity), it is also the continent that best preserves its environmental characteristics.

The Antarctic continent over time

Even though it is now a large, isolated landmass in the Southern Hemisphere, it was not always in this position. Throughout its paleogeographic history, it moved and changed as a result of constant tectonic movements throughout the geological eras. The environments of the south underwent significant change during this time period. The paleobotanical record that has been preserved in various geological contexts in Antarctica, with an emphasis on deposits from the Cretaceous period, shows that they were dominated by a vast diversity of species that made up and/or inhabited large forests during deep time. These species left their traces in the paleobotanical record.

Just like they are today, forest fires were very common shaping elements in terrestrial environments during the Cretaceous period. Past vegetation fires are evidenced, among other things, by the presence of fossilized charcoal, which originated from the carbonization process, which consists of the incomplete burning of plant fragments that are preserved in the geological record. This is one of the important environmental disturbance factors in various biomes. Various elements impact the event, recurrence, and force of regular flames in biological systems, from the occasional environment to the accessibility of plant material (fuel), dampness, and structures and reasons for starting.

Implications of the study

This research has established that, during the Cretaceous period, southern environments were also impacted by forest fires, which consumed vegetation partially or completely and occurred much more frequently than previously thought. The analysis of these carbonized plant fossil fragments found in Antarctica’s Cretaceous deposits, particularly those found on King George Island, allowed for the identification of the burned vegetation, which was primarily made up of gymnosperms. It likewise permitted the finding of the components engaged with the start of vegetation, consequently empowering the remaking of a straightforward paleoenvironmental situation.

“The forest fires that occurred during the same time period were also driven by the intense volcanism that was recorded in the Cretaceous, which makes up a large portion of the rock layers in Antarctica. However, contrary to what one might think, the vegetation was eaten by heated ash clouds, or pyroclastic clouds, that were expelled by the volcanoes and preserved in the geological record through very fine volcanic sediments like volcanic tuffs. This is in contrast to what one might think was the consumption of molten lava from active volcanism. Dr. Joseline Manfroi, the lead author, states, “These heated ash clouds reached the forests, causing the onset of natural vegetation fires.”

“It is possible to say that Antarctica’s environments were once ablaze throughout its geological history, as attested by the plant fossils that demonstrate the occurrence of fires in vegetation. Despite Antarctica’s negative temperatures and 98% coverage of ice on its territory in modern times, during the Cretaceous, fire frequently affected vegetation and shaped and disturbed southern forests, influencing the evolution and floristic diversity of these regions.”

More information: Joseline Manfroi et al, “Antarctic on fire”: Paleo-wildfire events associated with volcanic deposits in the Antarctic Peninsula during the Late Cretaceous, Frontiers in Earth Science (2023). DOI: 10.3389/feart.2023.1048754

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