Depositional Regime of Early Triassic Sedimentation in the Bjorne Formation on the Eastern Margin of the Sverdrup Basin Ellesmere Island, Nunavut, Canada Derrick Midwinter Supervisors Martin Gibling - Dalhousie University Thomas Hadlari - GSC Derrick Midwinter Supervisors Martin Gibling - Dalhousie University Thomas Hadlari - GSC

Interest/Objectives Poorly studied unit in the Canadian Arctic Create Deposition Model Understand Burial History Use results for Economic Potential and link back to Sverdrup Basin evolution Part of Geo-Mapping for Energy & Minerals for GSC – stratigraphy and economics Large scale fluvial system worth knowing Poorly studied unit in the Canadian Arctic Create Deposition Model Understand Burial History Use results for Economic Potential and link back to Sverdrup Basin evolution Part of Geo-Mapping for Energy & Minerals for GSC – stratigraphy and economics Large scale fluvial system worth knowing

STUDY AREA Regional Map Study Area Sverdrup Basin Embry and Beauchamp, 2008

Methods Conducted field work to create detailed section Collected samples for thin sections/ petrographic analysis N 1000m

Bjorne Formation Early Triassic sandstone unit deposited in Sverdrup Basin Tongues of shaly Blind Fiord Fm Dominantly fluvial Early Triassic sandstone unit deposited in Sverdrup Basin Tongues of shaly Blind Fiord Fm Dominantly fluvial BjorneBlind Fiord Near Study Area Embry, 2009

3 rd Member 2 nd Member 1 st Member Creating a Depositional Model 1,050m 250m Total Measured Section First Member Outcrop Quality

Facies Assemblage Se: Erosional Scours and Mud Clasts Sh, St: Horizontally Stratified, Trough Cross Stratification Sr: Sand with ripples

Facies Assemblage Sl: Low angle to sinusoidal cross stratification Fl: Silt to sand, fine lamination, very small ripples

Facies Assemblage Multistorey Fluvial Channels (Sl, Sh, Se, St, Sr) Sandstone unit with lineated low angle to horizontally stratified sandstone with primary current lineation or trough cross stratification sandstone, shallow elongate scours overlain by mudstone intraclasts Overbank Fines (Fl,Sr) Red bed dominantly siltstone with minor amounts of sandstone with climbing ripples, wavy laminations, desiccation cracks

Interpretation – Multistorey Fluvial Channels Shallow, elongate erosional scours Primary Current Lineation Sharp contact, preserved paleosurface

Interpretation – Overbank Fines Bioturbation, Ripple Lamination, Climbing Ripples Dessication Cracks

Depositional Environment: Ephemeral Sheet Flow Pulsatory deposition Rapid influx of sediment mainly as sheet flow Repeated events create multistorey sand sequences with high regime deposits dominating Red silt beds represent waning flood stages Pulsatory deposition Rapid influx of sediment mainly as sheet flow Repeated events create multistorey sand sequences with high regime deposits dominating Red silt beds represent waning flood stages

Evidence for Waning Flow Aggradation > Migration = Waning flow with high suspended and bed load Type B Climbing Ripples (Depositional Stoss) Silty veneer /Well-Preserved paleosurface - reflect fluctuating conditions during episodic flow Ashley et al., 1982

Evidence for Rapid Flow Transitional Dune or Antidune Upper Flow Regime Sedimentary Structures, (Fielding, 2006) OR Plane BedChute and Pool Bedform

Theory Why the fine grained sandy ephemeral braidplain? Provenance of Devonian siliciclastic material Paleoclimate – semi-arid – variable discharge Overlies Permo/Triassic boundary – influenced by extinction of vegetation – no meandering deposits Why the fine grained sandy ephemeral braidplain? Provenance of Devonian siliciclastic material Paleoclimate – semi-arid – variable discharge Overlies Permo/Triassic boundary – influenced by extinction of vegetation – no meandering deposits

Basin Evolution – Early Triassic Sediment Supply Embry and Beauchamp, 2008

Economic Potential Age equivalent to super giant oil field, Prudhoe Bay, Alaska Oil Sands on Melville Island Minimal organics in Bjorne, but present in Blind Fiord tongues and unit above 20% Porosity Potential stratigraphic-structural and flanks of salt dome traps Age equivalent to super giant oil field, Prudhoe Bay, Alaska Oil Sands on Melville Island Minimal organics in Bjorne, but present in Blind Fiord tongues and unit above 20% Porosity Potential stratigraphic-structural and flanks of salt dome traps Embry, 2009

Further Work Analyse facies for the remaining two members – create depositional model for entire Bjorne Study petrography for burial history and diagenetic information Overview hydrocarbon potential Analyse facies for the remaining two members – create depositional model for entire Bjorne Study petrography for burial history and diagenetic information Overview hydrocarbon potential

Thanks for your attention Questions?

Selected References Embry, A.F., 2009, Lower Triassic Stratigraphy and Petroleum Potential, Sverdrup Basin, Arctic Canada, Oral Presentation, AAPG Convention, Denver, Colorado, June 7-10, 2009 Embry, A.F. and Beauchamp, B., 2008, Sverdrup Basin. In: K.J. Hs ü, series editor: Sedimentary Basins of the World, Vol 5, The Sedimentary Basins of the United States and Canada, Andrew D. Miall. The Netherlands: Elsevier, 2008, pp. 451 – 471 Fielding, C.R., 2006, Upper flow regime sheets, lenses and scour fills: Extending the range of architectural elements for fluvial sediment bodies: Sedimentary Geology, v. 190, p Stear, W.M., 1985, Comparison of the bedform distribution and dynamics of modern and ancient sandy ephemeral flood deposits in the southwestern Karoo region, South Africa: Sedimentary Geology, v. 45, p Embry, A.F., 2009, Lower Triassic Stratigraphy and Petroleum Potential, Sverdrup Basin, Arctic Canada, Oral Presentation, AAPG Convention, Denver, Colorado, June 7-10, 2009 Embry, A.F. and Beauchamp, B., 2008, Sverdrup Basin. In: K.J. Hs ü, series editor: Sedimentary Basins of the World, Vol 5, The Sedimentary Basins of the United States and Canada, Andrew D. Miall. The Netherlands: Elsevier, 2008, pp. 451 – 471 Fielding, C.R., 2006, Upper flow regime sheets, lenses and scour fills: Extending the range of architectural elements for fluvial sediment bodies: Sedimentary Geology, v. 190, p Stear, W.M., 1985, Comparison of the bedform distribution and dynamics of modern and ancient sandy ephemeral flood deposits in the southwestern Karoo region, South Africa: Sedimentary Geology, v. 45, p