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TitleParalava and clinker from the Canadian Arctic: a record of combustion metamorphism dating back to the late Miocene
AuthorReinhardt, L; Estrada, S; Koglin, N; Piepjohn, K; Galloway, J MORCID logo
SourceCanadian Journal of Earth Sciences 2023 p. 1-33, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20220094
PublisherCanadian Science Publishing
Mediapaper; digital; on-line
File formatpdf; html
AreaCanadian Arctic; Ellesmere Island; Banks Island; Mackenzie Delta
Lat/Long WENS -84.0000 -80.0000 79.0000 78.0000
Subjectsgeneral geology; geochemistry; metamorphism; Cenozoic
Illustrationslocation maps; diagrams; photographs; tables; graphs; charts
ProgramGEM-GeoNorth: Geo-mapping for Energy and Minerals GEM Program Coordination
Released2023 05 26
AbstractOutcrops with conspicuous reddish to yellow-colored clinker, blackish paralava, and blends of both with a breccia-like appearance occur across the Canadian Arctic. We examined such rocks on Ellesmere Island, Banks Island, and the Mackenzie Delta area. These rocks are a product from natural combustion of bituminous shale and low-rank coal seams in Cretaceous and Paleogene host sedimentary rocks, respectively. The main mineral phases of clinker and silicate paralava samples are comprised of quartz + hematite ± feldspars ± cristobalite (or tridymite) ± cordierite–sekaninaite ± clinopyroxene ± sillimanite ± glass. Slag-like iron oxide paralava (74–95 wt.% total Fe2O3) consisting of hematite ± magnetite ± clinopyroxene occur in Paleogene host sedimentary rocks, rich in siderite concretions. The whole-rock geochemical composition of clinker and silicate paralava shows similarities for samples from the same outcrop. Regional and local specific elemental enrichments are mainly inherited from the sedimentary protoliths, which are characterized by volcanogenic input (Paleocene sedimentary rocks) or oxygen-depleted depositional conditions (Upper Cretaceous bituminous sedimentary rocks). Spontaneous combustion could take place when the organic-rich sedimentary rocks become exposed to atmospheric oxygen. This process has occurred at least since the Messinian stage (Miocene) on Ellesmere Island (6.1 ± 0.2 Ma; 40Ar/39Ar incremental heating dating on whole-rock paralava) and continues until now. An active combustion process on scree from a coal seam and clastic Eureka Sound Group sedimentary rocks was observed on Ellesmere Island.
Summary(Plain Language Summary, not published)
In the Canadian Arctic, Upper Cretaceous and Paleogene rocks are known to spontaneous combust. The products of these combustions are known as paralava or clinker. Samples of paralava and clinker were collected from several locations across the Canadian Arctic and Mackenzie Delta region and were analyzed for their geochemical composition and age. The mineralogy of the paralava and clinker are reported.

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