In the heart of peninsular India, beneath the layers of time and rock in the Godavari Basin, lies a charred archive of Earth’s fiery past. Scientists have now opened that archive using a powerful blend of microscopic analysis and advanced chemistry. What they found may change the way we read Earth’s geological and climatic history.

From the Late Silurian (spanning from 419.2 to 443.8 million years ago (mya) to the Quaternary (2.58 mya) period. Palaeofires left their mark on landscapes, influencing vegetation, climate, and even the formation of coal.

Scientists had long observed macroscopic charcoal in Permian coal-bearing formations across Gondwana, hinting at widespread wildfires. The Raniganj Coalfield in India was among the first sites where fossil charcoal was identified, revealing a connection between palaeomire systems and seasonal drought-induced fires.

High atmospheric oxygen levels during the Permian may have intensified these events, yet the exact nature of these fires—whether they were in situ burns or transported remnants—remained unclear. Geologists struggled to tell whether it was the result of local fires or transported by wind or water.

Scientists from Birbal Sahni Institute of Palaeosciences (BSIP) Lucknow, an autonomous institute of the Department of Science and Technology (DST), traced the fingerprints of ancient wildfires—palaeofires—that once swept through prehistoric landscapes some 250 million years ago during the Permian period.

The researchers embarked on a meticulous investigation, analyzing shale samples—fine-grained sedimentary rocks rich in organic material—collected from deep within the Godavari Basin. Using palynofacies analysis, they first categorized tiny particles of organic matter preserved in the rock.

Fig: Graphical abstract representing the integrated approach to resolve palaeofire activity during the Permian in Godavari Basin

These particles included translucent organic matter (TrOM) like pollen and plant bits, Palaeofire-induced charcoal (PAL-CH)—clear evidence of fire and Oxidized charcoal (OX-CH)—possibly transported or altered after burning.

The team led by Dr. Neha Aggarwal used techniques like Raman Spectroscopy, Rock-Eval Pyrolysis and FTIR Spectroscopy to truly decode the fire story etched in these ancient rocks.  

The study published in the journal ACS Omega provides a clear differentiation between in situ (on-site) and ex situ (transported) charcoal—a major leap in palaeofire research.

The team also made a remarkable observation --the stratigraphy—or layering—of the rock influenced how charcoal was deposited. Phases when sea levels dropped (regressive phases), well-preserved fire signatures were found. During sea level rise (transgressive phases), the charcoal was more mixed and oxidized, hinting at dynamic environmental shifts during the Permian.

Understanding how organic matter transforms during palaeofires provides insights into long-term carbon storage in Earth’s crust. This has major implications for carbon sequestration, a critical strategy in the fight against modern climate change.

It also offers geologists a refined lens through which to interpret past ecosystems, vegetation changes, and fire dynamics—vital tools for improving palaeoclimate reconstructions and geological dating techniques.

Publication link:  DOI: 10.1021/acsomega.4c08281

For more details, please contact Dr. Neha Aggarwal (neha[underscore]264840[at]yahoo[dot]co[dot]in).