Biomarkers in terrestrial organic matter from the Lower Devonian to Oligocene: Evidence from selected regions of the laurasian supercontinent
Notice bibliographique
Résumé
Biomarkers are chemical fossils which are valuable in organic matter provenance determination, and higher plant specific biomarkers could be utilised to deduce the precursor higher plants sources and their evolution through geological time. Twenty (20) selected rock samples from different areas within the Laurasian Supercontinent, including plant fossils of Lower Devonian to Oligocene Period from Canada, Germany, Northern Ireland, and the United Kingdom were examined for their record of aliphatic and aromatic biomarkers specific to higher plants. This aims to determine land plant-derived molecular compounds and its variations within the studied ages, as well as attribute biomarkers to different plant contributors. Aliphatic land plant biomarkers, including tetracyclic diterpenoids (beyerane, kaurane, phyllocladane) as well as high terrestrial/aquatic ratio (TAR >1) and conventional odd-numbered long-chain n-alkanes, which are derived from land plants were detected. Other aromatic land plant biomarkers, including naphthalenes and cadalene, were also distinguished in the samples. The presence of land plant biomarkers (beyerane, kaurane, phyllocladane, cadalene) and their slight increase in the examined Laurasian Devonian to Triassic samples signify the abundance and diversity of higher plants. Vascular plants, including psilophyton , pertica , leclercqia , drepanophycus , and sawdonia dominated the Lower Devonian flora (in the Rhynie Chert, for example), contributing to the evolution of the terrestrial ecosystem, with the diversity of seed plants, appearance of conifers and tall trees in the Carboniferous. Gymnosperms that appeared during the Upper Carboniferous period became the dominant flora in the Triassic and Jurassic periods, signalled by the abundance and increase in the concentration of higher plant biomarkers. The slight decrease of biomarkers post-Middle Jurassic may reflect organic matter degradation and erosion or mass extinction of plants and possible reorganisation in the plant fossil record marked by the Triassic-Jurassic boundary. Since land-plant derived biomarkers are not expected routinely in marine environments, the detected plant biomarkers in Jurassic marine sediments (Oxfordian and Kimmeridge shales) from England are interpreted to have been caused by run-off of terrigenous carbon from land to the marine environment. The study has enhanced our understanding of the organic matter provenance, terrestrialisation process, and spatiotemporal evolution of higher plants across different geological settings of the studied areas within the Laurasian Supercontinent. • We examined the ali- and aro-biomarkers in the TOM of the Laurasian Devonian to Oligocene ages. • TTD, naphthalenes and cadalene observed in the sediments are consistent with land plants. • Fluctuation of observed biomarkers through time revealed differential contributions of land plants to the ecosystem. • The sharp decrease of biomarkers post Middle Jurassic reflected possible mass extinction of plants at that time. • The study aided the understanding of terrestrialisation and higher plant evolution through geological time.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».