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TitleA revised stratigraphic framework for Cretaceous sedimentary and igneous rocks at Mokka Fiord, Axel Heiberg Island, Nunavut, with implications for the Cretaceous Normal Superchron
AuthorEvenchick, C A; Galloway, J MORCID logo; Saumur, B MORCID logo; Davis, W JORCID logo
SourceCanadian Journal of Earth Sciences vol. 56, no. 2, 2018 p. 158-174,
Alt SeriesNatural Resources Canada, Contribution Series 20180048
PublisherCanadian Science Publishing
Mediapaper; on-line; digital
File formatpdf
NTS49F; 49G; 59E; 59F; 59G; 59H; 69H; 340B; 340C; 560A; 560B; 560D
AreaAxel Heiberg Island; Mokka Fiord; Ellesmere Island
Lat/Long WENS -98.0000 -80.0000 82.0000 78.0000
Subjectsregional geology; stratigraphy; geophysics; paleontology; geochronology; stratigraphic analyses; chronostratigraphy; field relations; bedrock geology; lithology; sedimentary rocks; sandstones; shales; siltstones; igneous rocks; volcanic rocks; volcanic ash; intrusive rocks; diabases; granitic rocks; gabbros; host rocks; paleomagnetism; magnetic field; paleomagnetic interpretations; tectonic interpretations; tectonic history; magmatism; intrusions; emplacement; micropaleontology; palynology; petrographic analyses; radiometric dates; argon argon dates; Cretaceous Normal Superchron; Sverdrup Basin; High Arctic Large Igneous Province (HALIP); Isachsen Formation; Paterson Island Member; Walker Island Member; Rondon Member; Strand Fiord Formation; Christopher Formation; Phanerozoic; Mesozoic; Cretaceous
Illustrationslocation maps; geoscientific sketch maps; stratigraphic charts; tables; photographs; aerial photographs
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic, High Arctic LIP
Released2018 11 07
AbstractNew data and interpretations on geological relationships of igneous rocks at Mokka Fiord, Axel Heiberg Island, Nunavut, provide insight into the timing and nature of magmatism associated with the Sverdrup Basin and High Arctic Large Igneous Province (HALIP). Field relationships indicate that the igneous rocks, previously interpreted to be volcanic flows, are most likely an intrusive unit discordant to regional bedding. An intrusive origin helps resolve chronostratigraphic inconsistencies in previous work. The host rocks are palynologically constrained to be late Barremian to late Aptian in age and are interpreted to be Paterson Island or Walker Island member of the Isachsen Formation. If the igneous body is intrusive, it's previously reported Ar-Ar age (102.5 ± 2.6 Ma) is no longer in conflict with accepted stratigraphic interpretations and probably reflects the emplacement age of the intrusion. Lingering uncertainties in interpreting the normal and reverse magnetic polarities determined in the previous work remain, and both are considered viable. Although this uncertainty precludes definitive conclusions on the significance of paleomagnetic data at Mokka Fiord, examination of the stratigraphic, paleomagnetic, and geochronologic relationships there highlight potential for the study of excursions, or reversed magnetic polarity subchrons, in the Cretaceous Normal Superchron elsewhere in the HALIP.
Summary(Plain Language Summary, not published)
The paper presents new data and interpretations on Cretaceous igneous rocks and surrounding sedimentary rocks exposed at Mokka Fiord, eastern Axel Heiberg Island, Nunavut, in Canada's High Arctic. The igneous rocks are determined to be intrusive, in contrast to previous interpretations suggesting they were volcanic flows. These new findings have implications on the interpretations of previous paleomagnetic data obtained at Mokka Fiord. Further work on such Cretaceous Igneous rocks of the High Arctic Large Igneous Provice, which record magnetic polarity, could help us understand how the Earth's magnetic field varied during the Cretaceous Normal Polarity Superchron.

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