The Permian-Triassic(P/T)transition is marked by the most severe mass-extinction event of the Phanerozoic.Although much is known about this event in the marine realm,there are many open questions regarding what happen...The Permian-Triassic(P/T)transition is marked by the most severe mass-extinction event of the Phanerozoic.Although much is known about this event in the marine realm,there are many open questions regarding what happened during this period to many continental biota.In the case of plants,a drastic mass-extinction event has even been negated by some authors.To add about the knowledge on continental biota in India during this crucial time period,the present study analysed the palynology,palynofacies,organic geochemistry(biomarkers),stable isotopes,and charcoal within the subsurface Gondwana deposits of the Kamthi Formation(late Permian-early Triassic)from core TTB-7 from the Tribida block,located in the Talcher Coalfield of the Mahanadi Basin,India.The primary objectives are to validate the age of the strata,ascertain the palaeodepositional setting of the palaeomire,and propose palaeobotanical evidence regarding the occurrence of wildfires within this stratigraphic succession and changes in floral content across the P/T transition.The palynological study proposes two palynoassemblage zones,Densipollenites magnicorpus and Klausipollenites schaubergeri,suggesting a latest Permian(Lopingian)and early Triassic(Induan?)age for the studied succession,respectively.The age is also inferred based on correlation with coeval assemblages from India and other Gondwana continents.The palynoassemblages reveal the dominance of Glossopteridales and Coniferales along with Filicales,Lycopsidales,Equisetales,Cordaitales and Peltaspermales.The relatively higher values of the carbon preference index and terrigenous/aquatic ratio also suggest higher plant input.However,a bimodal n-alkane distribution pattern suggests the contribution of terrigenous and microbial sources.Although the occurrences of long-chain alkanes indicate input of higher plants,the low Pwax values(<0.26)suggest relatively less contribution.The Paqvalues(≅1)and amorphous organic matter(av.33.24%)suggest a significant macrophyte input in the studied samples,pointing to the occurrence of moderate aquatic conditions in the basin.Furthermore,the distribution of hopanoids and the content of degraded organic matter(av.29.96%)reflect the bacterial degradation of organic matter.Also,the δ^(13)C values of the studied section varied from−31.2‰to−21.8‰.A large carbon isotopic offset of 9.4‰across the P/T transition,Pr/Ph ratio(0.3–1.3)and shift in the distribution pattern of palynofacies components is indicating a significant change in climatic conditions.Moreover,the presence of macroscopic charcoal fragments of gymnospermous affinity with pre-charring colonization by fungi provides evidence for wildfire occurring during the Lopingian(Late Permian)in this basin.展开更多
Inertinite,as an important and abundant maceral group in coal,is critical for the study of palaeowildfires and their roles in the Earth’s ecosystems.Recently,there has been a significant amount of research on the rel...Inertinite,as an important and abundant maceral group in coal,is critical for the study of palaeowildfires and their roles in the Earth’s ecosystems.Recently,there has been a significant amount of research on the relationship between palaeowildfire,palaeoclimate change and palaeovegetation evolution based on inertinite data.The reflectance of fusinite and semifusinite has been used to estimate the combustion temperature and type of palaeowildfires,and then to evaluate the combustion characteristics of different types of palaeowildfires.The relative abundance of inertinite can be used to estimate the atmospheric oxygen contents.The rapid development of artificial intelligence(AI)and online tools to search scientific databases has presented an opportunity for us to find,collect,arrange,and analyse data from the earliest to latest publications on inertinite.The data extraction tool Deep Shovel is used to collect and analyse global inertinite data from the Silurian to the Neogene.The software programs such as Gplates,ArcGIS pro and Tableau are then applied to model the relative abundance of inertinite over geological time,which can be correlated with other parameters such as atmospheric oxygen contents,plant evolution and palaeoclimate changes.The distribution of inertinite in coals varied over different geological periods,being typified by the“high inertinite content-high atmospheric oxygen level”period in the Permian and the“low inertinite content-low atmospheric oxygen level”period in the Cenozoic.This study has proposed a possible model of the positive and negative feedbacks between inertinite characteristics and palaeoenvironmental factors,and has revealed the exceptional role of inertinite in palaeoenvironmental studies.Future research on inertinite will be focused on the integrated study of organic petrology and organic geochemistry of inertinite,the big data-driven research on the temporal and spatial distribution of the global inertinite,the exploration of the functions of palaeowildfires in the Earth systems in different climatic backgrounds,and the study of modern wildfires to better predict the future frequency and intensity of wildfires due to climate changes.展开更多
基金The authors are thankful to the Director(Prof.Mahesh G.Thakkar),Birbal Sahni Institute of Palaeosciences,Lucknow for providing the necessary permission and laboratory facilities to carry out this work(BSIP/RDCC/Publication no.73/2024-25)Author(SM)expresses sincere thanks to DST(Govt.of India)project no.EEQ/2018/000303 for the financial support.
文摘The Permian-Triassic(P/T)transition is marked by the most severe mass-extinction event of the Phanerozoic.Although much is known about this event in the marine realm,there are many open questions regarding what happened during this period to many continental biota.In the case of plants,a drastic mass-extinction event has even been negated by some authors.To add about the knowledge on continental biota in India during this crucial time period,the present study analysed the palynology,palynofacies,organic geochemistry(biomarkers),stable isotopes,and charcoal within the subsurface Gondwana deposits of the Kamthi Formation(late Permian-early Triassic)from core TTB-7 from the Tribida block,located in the Talcher Coalfield of the Mahanadi Basin,India.The primary objectives are to validate the age of the strata,ascertain the palaeodepositional setting of the palaeomire,and propose palaeobotanical evidence regarding the occurrence of wildfires within this stratigraphic succession and changes in floral content across the P/T transition.The palynological study proposes two palynoassemblage zones,Densipollenites magnicorpus and Klausipollenites schaubergeri,suggesting a latest Permian(Lopingian)and early Triassic(Induan?)age for the studied succession,respectively.The age is also inferred based on correlation with coeval assemblages from India and other Gondwana continents.The palynoassemblages reveal the dominance of Glossopteridales and Coniferales along with Filicales,Lycopsidales,Equisetales,Cordaitales and Peltaspermales.The relatively higher values of the carbon preference index and terrigenous/aquatic ratio also suggest higher plant input.However,a bimodal n-alkane distribution pattern suggests the contribution of terrigenous and microbial sources.Although the occurrences of long-chain alkanes indicate input of higher plants,the low Pwax values(<0.26)suggest relatively less contribution.The Paqvalues(≅1)and amorphous organic matter(av.33.24%)suggest a significant macrophyte input in the studied samples,pointing to the occurrence of moderate aquatic conditions in the basin.Furthermore,the distribution of hopanoids and the content of degraded organic matter(av.29.96%)reflect the bacterial degradation of organic matter.Also,the δ^(13)C values of the studied section varied from−31.2‰to−21.8‰.A large carbon isotopic offset of 9.4‰across the P/T transition,Pr/Ph ratio(0.3–1.3)and shift in the distribution pattern of palynofacies components is indicating a significant change in climatic conditions.Moreover,the presence of macroscopic charcoal fragments of gymnospermous affinity with pre-charring colonization by fungi provides evidence for wildfire occurring during the Lopingian(Late Permian)in this basin.
基金supported by the National Natural Science Foundation of China(Grant Nos.42321002,41572090)the Deep-time Digital Earth(DDE)Big Science Program。
文摘Inertinite,as an important and abundant maceral group in coal,is critical for the study of palaeowildfires and their roles in the Earth’s ecosystems.Recently,there has been a significant amount of research on the relationship between palaeowildfire,palaeoclimate change and palaeovegetation evolution based on inertinite data.The reflectance of fusinite and semifusinite has been used to estimate the combustion temperature and type of palaeowildfires,and then to evaluate the combustion characteristics of different types of palaeowildfires.The relative abundance of inertinite can be used to estimate the atmospheric oxygen contents.The rapid development of artificial intelligence(AI)and online tools to search scientific databases has presented an opportunity for us to find,collect,arrange,and analyse data from the earliest to latest publications on inertinite.The data extraction tool Deep Shovel is used to collect and analyse global inertinite data from the Silurian to the Neogene.The software programs such as Gplates,ArcGIS pro and Tableau are then applied to model the relative abundance of inertinite over geological time,which can be correlated with other parameters such as atmospheric oxygen contents,plant evolution and palaeoclimate changes.The distribution of inertinite in coals varied over different geological periods,being typified by the“high inertinite content-high atmospheric oxygen level”period in the Permian and the“low inertinite content-low atmospheric oxygen level”period in the Cenozoic.This study has proposed a possible model of the positive and negative feedbacks between inertinite characteristics and palaeoenvironmental factors,and has revealed the exceptional role of inertinite in palaeoenvironmental studies.Future research on inertinite will be focused on the integrated study of organic petrology and organic geochemistry of inertinite,the big data-driven research on the temporal and spatial distribution of the global inertinite,the exploration of the functions of palaeowildfires in the Earth systems in different climatic backgrounds,and the study of modern wildfires to better predict the future frequency and intensity of wildfires due to climate changes.
