Impact of palaeo-wildfires on higher plant parameter revealed by new biomarker indicator

Abstract

Palaeo-wildfires were a common phenomenon in the Earth history. Their products can influence on some biomarker indicators characterising palaeo-environment conditions. Selected plant-derived aromatic biomarkers and polycyclic aromatic hydrocarbons (PAHs) were analysed in the Jurassic strata from the Polish Basin, Jurassic strata from the Mesozoic basement of the Carpathian Foredeep and Neogene strata from the Carpathian Foredeep. Marked compounds recorded varied input from palaeoflora families and the variable intensity of palaeo-wildfires. Retene (Ret), cadalene (Cad), 6-isopropyl-1-isohexyl-2-methylnaphthalene (ip-iHMN), dehydroabietic acid methyl ester (DAME), simonellite (Sim), fluoranthene (Fl), benz[α]anthracene (BaA), benzo[α]pyrene (BaP), benzo[ghi]perylene (BgP), coronene (Cor) were identified in the analysed samples. Based on mentioned compounds, pyrolytic input ratio (PIR) defined as (Cad + Sim + TDHA+ip-iHMN+Fl + BaA + BaP + BgP + Cor)/(Cad + Sim + TDHA+ip-iHMN) was proposed. To provide broader possibility of use, the total dehydroabietic acid (TDHA) counted as sum of DAME and free dehydroabietic acid was used in PIR equation. PIR manage to define pyrolytic organic matter input. Combination of PIR with higher plant parameter (HPP) results, defined as Ret/(Cad + Ret), enables the distinction of samples deposited in a warm/hot and humid palaeo-climate from these deposited in more arid conditions, which were affected by palaeo-wildfires. Heretofore, high HPP values have been interpreted as an evidence of a warm/hot and humid palaeo-climate. This interpretation is true when PIR values are low. If the PIR values were higher, then the palaeo-wildfires influence on HPP was more significant and palaeo-climate misinterpretation was more probable. The new indicator can be used in case of immature or early mature and mostly terrestrial organic matter.