What can fire reveal about Earth's past? This is a question that a group of researchers linked to the Postgraduate Program in Environment and Development (PPGAD, acronym in Portuguese) of the University of Vale do Taquari - Univates seeks to answer. They develop studies in the areas of paleobotany and paleofires. Evidence of fires, including the macro-charcoal, are important instruments to expand the understanding that we have about natural systems and environments from millions of years ago. Univates' research activities in the area take place in the Laboratory of Paleobotany and Biome Evolution of the Univates Science Museum.
Last October, a group of Brazilian research institutions, including Univates, revealed an unprecedented study on the occurrence of paleofires in Antarctica 75 million years ago, in the Cretaceous period. This scenario has been expanded with further studies and, now, a new research developed in partnership between Univates and three other institutions attests that India also had fires in the Lower Cretaceous, in a period between 145 million and 100.5 million years ago.
The new study, published in the Current Science journal, takes a look at a part of India where macro-charcoal (fossil charcoal) records were non-existent. This location corresponds to the Saurashtra sedimentary basin, which in the present-day represents Saurashtra region of northwestern India and close to the Arabian Sea.
The study of these records is important and allows drawing conclusions about the composition of the vegetation affected by the fire and some of the conditions of the surrounding areas as well as expanding the knowledge about the geological past of a given location. Considering the occurrence of macro-charcoal, only a few records have been published for the strata in India and they are mainly originating from the Permian deposits (from 298.9 to 251.9 million years ago).
The author of the work reveals that the research on this topic was motivated by the lack of studies on paleofires occurred in India during the Cretaceous and by the total absence of macro-charcoal records for an entire sedimentary basin, in this case the Saurashtra basin. “This information gap raised the question of whether or not there was fire in the area, and, if so, which vegetation gave rise to the macro-charcoal. These questions, this restlessness that is inherent to scientific research, can help to try to understand what the environment was like under the influence of paleofires”, she details.
Scientific research indicates that the Cretaceous was one of the periods with the highest incidence of paleofires in the history of the Earth, a high concentration of (paleo)oxygen, high temperatures and the delimitation of current continental limits through continental drift. However, the distribution of these fossilized coal records is uneven between hemispheres - the Northern Hemisphere has a much higher amount of records than the Southern Hemisphere. Given this context, researches such as Gisele’s contributes to establish new limits for scientific knowledge in the area.
“Therefore, the study helps to understand the distribution in the Southern Hemisphere - remembering that in the Cretaceous India was in the Southern Hemisphere -, since paleofires are expected to have similar occurrences in both hemispheres. In this Cretaceous global scenario, our study provides yet another important evidence that fires could indeed occur in greater volumes, even though there are still some places in the Southern Hemisphere with regional and temporal gaps, which acted in the dynamics involved in the evolution of ecosystems until today”, adds Gisele.
In addition, by looking at the past, the study helps to understand the functioning of both deep time and present natural systems, and it can help understanding the natural and anthropic processes related to climate change currently underway on Earth.
Future perspectives
New studies are being yielded by the Univates team along with the Laboratory of Paleobotany and Evolution of Biomes. Gisele, in particular, is currently analyzing material from a Brazilian sedimentary basin, also from the Lower Cretaceous.
