Monday, June 20, 2016

Summary of rock formations on Axel Heiberg Island

This information was compiled with Rachel Maj and Maria Shaposhnikova.  Summaries are from Harrison and Jackson (2014).  This post will be continually updated as we develop a better understanding of the Axel Heiberg strata, and the significance each of the units plays in studying diapirism on the island.

(Written in order of depositional history, oldest at the top)

Borup Fiord Formation

  • Early to Late Carboniferous
  • Thickness ranges from 40 - 1100 m.
  • Northern Axel Heiberg Island
  • Red weathered Quartz Sandstone + Polymictic conglomerate
  • Minor Arenaceous Limestone
  • Locally abundant non-marine carbonate
  • Interpreted as proximal alluvial fans grading into stream channel, braidplain, overbank on distal alluvial fans
Otto Fiord Formation
  • Early to Late Carboniferous
  • Up to 410 m thick
  • Source of all evapouritic diapirs in central Sverdrup Basin
  • Stratified, 8-50 m thick Anhydrite and Limestone cycles, rare dolostone and sandstone
  • Diverse fossils present in limestones
  • Localized brecciation
  • Sparse halite on Axel Heiberg

Hare Fiord and Trappers Cove Formations
  • Late Carboniferous
  • Up to 1200 thick combined
  • Siltstone, Shale, Siliceous Shale, Spiculitic Chert, Limestone
  • Exposed on northern and eastern Axel Heiberg Island
  • Strata occurs in incomplete Bouma cycles
Van Hauen and Black Stripe Formations
  • Lower to Upper Permian
  • Combined thickness between 180 to 360 m 
  • Result of sediment starvation
  • Dark, fissile shale, dark siltstone, dark chert.  Rare limestone

Blind Fiord Formation

  • May be between 1000-1500 m thick
  • Siltstone and shale, some red weathering
  • Soft sediment deformation, cross bedding
  • Annelid worm tracks (Zoophycos?)
  • Late Permian to Early Triassic
  • Contains cretaceous gabbro sills that conformably overlie the Van Hauen Formation

Blaa Mountain Group

  • Contains four formations:  Murray Harbour, Buchanan, Hoyle Bay, and Barrow Formations
  • Dark shale, weathered siltstone, sandy siltstone
  • Clay ironstone concretions
  • 245.9-203.6 Ma
  • Thin towards diapirs

Heiberg Formation

  • Three members Romulus (pale sandstone, siltstone, shale, coarsening upwards cycles) Fosheim (light sandstone, less siltstone, carbonaceous shale, coal interbeds) Remus (light sandstone, quartz and iron cement, clay)
  • Red weathering - iron likely comes from Fosheim member
  • ~331-1422 m thick
  • This formation is important evidence for the salt diaprism

Savik beds

  • Composed of the Jameson Bay Formation, Sandy Point Formation, McConnell Island Formation, and Ringes Formation
  • Lower Jurassic
  • Dark grey to black shale, glauconitic shale and sandstone  - Formations are grouped together because they are not possible to distinguish outside of the hand sample scale 
  • 270 m to 819 m in thickness

Awingak Formation

  • Quartzose sandstone and shale
  • Approximately 345 m thick
  • Plant debris, coal, roots
  • Thins by more than 50% adjacent to diapris
  • Hornfels and breccias
  • 161.2-161.8 Mya
  • Debris flows
  • Lots written about this - might be relevant to return to

Deer Bay Formation

  • Kimmeridgian to mid-Valanginian (Late Jurassic to Early Cretaceous)
  • Silty shale, clay ironstone interbeds, black silty shale
  • Characterized by presence of glendonites

Isachsen Formation

  • Valanginian to Aptian (Early Cretaceous)
  • 92 to 1372 m in thickness
  • Light quartz sandstone with lesser carbonaceous siltstone, shale and coal
  • Coarsening upwards cycles
  • Contains the Rondon Member (coarsening upwards cycles of shale, siltstone, bioturbated sandstone), the WalkerIsland Member (coarsening and fining upwards cycles of sandstone, carbonaceous siltstone and shale)
  • Some mafic sills

Christopher Formation

  • Dark shale and silty shale, minor siltstone, and very fine grained sandstone
  • Total range in thickness 343 to >2100 m (including areas of thinning and minibasins, but generally 442-1100 m
  • Early Cretaceous
  • Splits into the Invincible Point Member and the McDougall Point Member, members are separated by the Junction beds at top of Invincible Point Member
  • Invincible Point Member - lower 645 m of formation, dark silty shale, some ironstone and calcareous mudstone concretions, glendonites, petrified wood.  Interbeds of sandstone, tuff, and siltstone, contains stratified anhydrite
  • Junction beds - up to 60 m thick, coarsening and thickening upwards cross-bedded sandstones to the north
  • Macdougall Point Member - dark silty shale, with siltstone and fine sandstone, concretions and petrified wood, 210-550 m

Hassel Formation

  • 80% Sandstone, 20% shale, 5-20 m coarsening upwards cycles at Expedition Fiord
  • Sandstones are medium grained calcarrious and dolomitic arkose and subarkoses at E
  • 105 to > 500 m thick
  • Covered by basalt and other mafic talus
  • Early Cretaceous

Bastion Ridge Formation

  • Early Cretaceous
  • Shale, siltstone, minor thin beds of sandstone and sideritic ironstone
  • 5-242 m thick
  • Contains mafic sills and volcanic flows

Strand Fiord Formation

  • Early to Late Cretaceous, may be conformable and contemporaneous with the Kanguk Formation
  • Sucesssion of basalt, agglomerate, and pyroclastic deposits
  • 40-1033 m thick
  • Flows are 15-60 m thick
  • Flow tops are vesicular and amygdaloidal
  • Flows have aa, pahoehoe, and blocky textures
  • Some hyaloclastic flows, ash-fall deposits and fluvial conglomerates

Intrusive igneous rocks

  • Mafic
  • Coarse to medium grained (gabbro-diabase)
  • Dyke swams, including the Queen Elizabeth and Surprise dyke swarms (Surprise!  It's a dyke swarm!)
  • No strong relationship between age, trend, and stratigraphic level of emplacement
  • Older dykes may have facilitated flows in younger units
  • Early Creataceous - Ages of dykes are not well constrained at the Age level

Kanguk Formation

  • Late Cretaceous
  • Thickness between 31-847 m
  • Dark shale, interbeds of sandstone and siltstone

Expedition Formation
  • Late Cretaceous
  • Comprises a lower and upper member
  • Lower member is 160-947 m thick
  • Lower member is ~60% shale, ~40% sandstone
  • Sandstones in Lower member contain planar tabular cross-stratification, ripples, plant fragments, bioturbation, and is organized in both fining and coarsening upwards cycles
  • Upper Member is 0-746 m thick
  • Upper member is sandstone and shale in coarsening upwards cycles
  • Upper member sandstone is medium to coarse grained cross-bedded sandstone
  • Upper member grades into shale and carbonaceous shale to the west
  • Upper member contains pebble lags

Strand Bay Formation

  • 53 to 783 m thick
  • Paleocene
  • Shale dominated, with sandstone interbeds
  • Coal seams

Iceberg Bay Formation

  • Paleocene to Eocene
  • Composed of the Lower Member and the Coal Member
  • Full description in Ricketts (1991)
  • Lower Member consists of 30-50% sandstone, shale, and coal 
  • Lower Member is up to 1838 m thick
  • Lower Member consists of 15-45 m coarsening-upwards cycles
  • The Coal Member is well preserved
  • The Coal Member is up to 1060 m thick
  • The Coal Member contains 1-10 m beds of fining upwards sandstone, coal, and shale
  • The Coal Member contains fossil wood, lags of mud chips, and leaf imprints

Pleistocene and Holocene Sediments

  • Gravels, Diamicts (till)
  • Authors provide interpretations rather than unit descriptions

Jackson, M.P.A., and Harrison, J.C., 2006, An allochthonous salt canopy on Axel Heiberg Island, 
       Sverdrup Basin, Arctic Canada: Geology, v. 34, no. 12, p. 1045–1048, doi: 10.1130/G22798A.1.

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