Triassic micro-charcoal as a promising puzzle piece in palaeoclimate reconstruction: An example from the Germanic Basin

Fossil charcoal is the primary source of evidence for palaeo-wildfires and has gained increasing interest as a proxy in the reconstruction of past climates and environments. Today, increasing temperatures and decreasing precipitation/humidity appear to correlate with increases in the frequency and intensity of wildfires in many regions worldwide. Apart from appropriate climatic conditions, sufficient atmospheric oxygen (>15%) is a necessary precondition to sustain combustion in wildfires. The Triassic has long been regarded as a period without evidence of wildfires; however, recent studies on macro-charcoal have provided data indicating their occurrence throughout almost the entire Triassic. Still, the macro-palaeobotanical record is scarce and the study of micro-charcoal from palynological residue is seen as very promising to fill the gap in our current knowledge on Triassic wildfires. Here, the authors present the first, verified records of micro-charcoal from the Triassic of the Germanic Basin, complementing the scarce macro-charcoal evidence of wildfires during Buntsandstein, Muschelkalk and Keuper (Anisian-Rhaetian). The particles analysed by means of scanning electron microscopy (SEM) show anatomical features typical of gymnosperms, a major element of the early Mesozoic vegetation following the initial recovery phase after the PT-boundary event. From the continuously increasing dataset of Triassic charcoal, it becomes apparent that the identification of wildfires has a huge potential to play a crucial role in future studies, deciphering Triassic climate dynamics. The first SEM study of micro-charcoal from palynological residue spanning the entire Triassic period, presented here, is a key technique to further unravel the charcoal record as a puzzle piece in palaeoclimate reconstruction.