Organic geochemical data of higher plant coals from Svalbard and Northeast Greenland reveal implications for a connected Paleogene setting

The organic geochemistry of Paleogene coals from central Spitsbergen (Longyearbyen and Grumantbyen) and northeast Greenland (Thyra Ø Island and Kronprins Christian Land), which were sampled during a BGR expedition in 2018, was studied using Rock-Eval and gas chromatography-mass spectrometry.

Rock-Eval data and biomarker distributions of the coals (e.g. hopanoids and hopanoic acids) demonstrate a low coal rank for both, but a lower thermal maturity of coals from Greenland compared to those from Svalbard. The generally high abundance of hopanoids implies a strong bacterial reworking of the organic matter, whereas sulphur occurrences indicate a marine influence after organic matter deposition. A great variety of higher plant biomarkers was detected in all coals. Distinctive compounds recorded in the coals are aliphatic and aromatic diterpenoids as well as partly aromatised picenes, indicating strong input of conifers and angiosperms. The oxicity of the paleo-swamps was determined with pristane and phytane based ratios: Tentatively organic matter was deposited in a fluvio-deltaic setting at both sites.

This study provides a detailed geochemical investigation of so far understudied coals from northeast Greenland. Moreover, it aims to enhance our understanding of formerly connected Paleogene settings from Spitsbergen and Greenland in terms of their paleoecology, primary input into coal swamps and individual thermal history. Our data also give insights into an Arctic environment that existed at comparably high latitudes as today, but at times close to the Paleocene-Eocene Thermal Maximum (PETM), where it supported the development of extensive swamps and forests.