Pliocene coal-seam fires on southern Ellesmere Island, Canadian Arctic
Estrada, Solveig; Piepjohn, Karsten; Frey, Manfred J.; Reinhardt, Lutz; Andruleit, Haraldvon; Gosen, Werner
published: Jan 27, 2009
ArtNo. ESP155025101003, Price: 29.00 €
Evidence for fossil coal-seam fires was found on southern Ellesmere Island, Queen Elizabeth Islands, Canadian High Arctic. Multicoloured, thermally altered but unmelted rocks (clinker) and black, melted rocks (paralava) occur in Lower Palaeogene clastic sediments that contain coal seams. XRD, XRF, microscopic and EMP studies detected two varieties of paralava: silicate paralava consisting of a large variety of high-temperature/low-pressure minerals (cordierite, mullite, tridymite, cristobalite, hematite, magnetite-spinel-hercynite-ulvöspinel solid solutions in glass) typical of combustion metamorphism, and uncommon, almost pure iron-oxide paralava. The coal burned 3.3 ± 0.5 Ma ago in the Middle Pliocene (40Ar-39Ar incremental heating dating on whole-rock silicate paralava) during a relatively warm climatic phase, when the Palaeocene to Lower Eocene strata with the coal seams were uplifted to a position close to the surface. The coal fires were ignited by spontaneous combustion or by forest fires and enhanced by air circulation through pre-existing faults and fractures.