|Title||Volcanology and geochemistry of HALIP flood basalts, Axel Heiberg Island, Nunavut|
|Author||Williamson, M C; Saumur, B M; Evenchick, C A; Little, K J; Cousens, B L|
|Alt Series||Natural Resources Canada, Contribution Series 20170002|
|Meeting||Geological Association of Canada-Mineralogical Association of Canada, Annual Meeting,14-18 May, 2017, Kingston, Ontario, Canada; Kingston; CA; May 14-18, 2017|
|Media||paper; on-line; digital|
|Related||This publication is related to Williamson, M -C; Jackson, S
E; Yang, Z; Venance, K; Hunt, P; (2018). Magma recharge and mixing processes in continental flood basalt reservoirs: evidence from melt inclusions in basalts from the High Arctic Large Igneous Province, Axel Heiberg Island, Nunavut, Geological Survey
of Canada, Open File 8377|
|Area||Axel Heiberg Island; Bunde Fiord; Strand Fiord; Plateau Lake|
|Subjects||general geology; geochemistry; basalts; volcanism; lava flows; Sverdrup Basin; HALIP flood basalts|
|Program||Western Arctic, High Arctic LIP, GEM2: Geo-mapping for Energy and Minerals|
|Links||Online - En ligne|
|Abstract||Geochemical studies of continental flood basalts are often hindered by a lack of stratigraphic control in areas where sheet flows were emplaced over geologically short time intervals. The advantage of
studying flood basalts in a basin setting is that the time-sequence of eruptions is well-defined, thus providing a robust stratigraphic framework for lithogeochemical studies. |
Fieldwork in the Sverdrup Basin was carried out in 2015 and 2016
as part of the GEM 2-High Arctic Large Igneous Province (HALIP) research activity. A particular emphasis was placed on the stratigraphy, physical volcanology and geochemistry of flood basalts in the Strand Fiord Formation. Detailed investigations
were carried out at two locations on western Axel Heiberg Island: along the south shore of Bunde Fiord, and near Plateau Lake, to the north of Strand Fiord.
Previous studies demonstrated that the ~ 95 Ma Strand Fiord Formation consists of
sheet flows of uniformly basaltic composition displaying aa and pahoehoe textures. Fieldwork near Plateau Lake suggests a total thickness of 980 m at this locality. The 3-D exposure of ~500 m of section alongside a retreating glacier makes this an
excellent opportunity to study the evolution of a flood basalt province. Invasive flows near the base of the succession consist of a chaotic mélange of basaltic lava and blocks of sandstone. These flows are overlain by a bed of shale containing
volcanic bombs and discontinuous lenses of fine-grained sandstone that locally contain fiamme. Thick lava flows are characterized by grey, unoxidized flow tops and show structures such as basalt colonnades and entablatures. In contrast, volcanic
successions near Bunde Fiord consist of lava flows separated by well-defined oxidized flow tops. A single bed of crystal tuff occurs near the base of the succession. The flows are uniformly of aa type, and lack the complex intraflow structures
observed at Plateau Lake and in the type area at Strand Fiord.
Flood basalts in the Strand Fiord Formation should form a coherent petrogenetic series if individual sections were once part of a single basaltic plateau. A comparative
geochemical study of lava flows in both areas suggests that most eruptions tapped steady-state magmas rising from a shallow reservoir. At Bunde Fiord, the mineralogy and geochemistry of lava flows show compelling evidence for episodic magma recharge
and mixing processes consistent with periods of quiescence between eruptions. We propose a model for the emplacement of HALIP flood basalts that integrates field observations with the results of petrochemical studies.
|Summary||(Plain Language Summary, not published)|
This publication describes the results of bedrock mapping and sampling activities carried out in 2015 under the GEM 2 HALIP Activity. The authors
present the first detailed study of the eruptive style in Strand Fiord Formation exposed near Plateau Lake, western Axel Heiberg Island. Results also include major and trace element data for basaltic lava flows sampled within the ~ 1 km thick
volcanic succession. The authors interpret the compositional trends in flood basalts of the Strand Fiord Formation in the context of other HALIP project results. The study carries important implications for the economic potential of the HALIP
magmatic system in this region of Nunavut.