Neoproterozoic Windermere Supergroup, Southern Canadian Cordillera

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Neoproterozoic Windermere Supergroup, Southern
Canadian Cordillera -- Worldclass Ancient
Laboratory for the Study of Deep-Marine Sedimentar
y Rocks and Sedimentary Processes
R.W.C. Arnott Dept. of Earth Sciences University
of Ottawa Ottawa, ON, Canada
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Deep-water architectural elements
(Posamentier and Kolla 2003)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Outcrop Distribution of the Neoproterozoic
Windermere Supergroup
Modified from Ross et al. (1995)
3rd B.C. Unconventional Gas Technical Forum (2009)
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WINDERMERE SUPERGROUP, SOUTHERN CANADIAN
CORDILLERA
3rd B.C. Unconventional Gas Technical Forum (2009)
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Windermere Stratigraphy in Cariboo Mtns
3rd B.C. Unconventional Gas Technical Forum (2009)
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Schematic Windermere Paleogeography
3rd B.C. Unconventional Gas Technical Forum (2009)
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Canyons/erosional channels
OFP
3rd B.C. Unconventional Gas Technical Forum (2009)
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Leveed channels
3rd B.C. Unconventional Gas Technical Forum (2009)
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Basin floor
3rd B.C. Unconventional Gas Technical Forum (2009)
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Deep-water architectural elements
(Posamentier and Kolla 2003)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Einstein Channel, GOM
Joshua Channel, GOM
5 km
Posamentier and Walker, 2006
3rd B.C. Unconventional Gas Technical Forum (2009)
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SMALL channels lt 15 m thick and few 100 m
wide
1250 m
3rd B.C. Unconventional Gas Technical Forum (2009)
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Sinuous channels lateral accretion packages
(LAPs) point bars deposits
Abreu et al. 2003
Posamentier and Walker, 2006
3rd B.C. Unconventional Gas Technical Forum (2009)
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Isaac Channels 1 to 6 (leveed channels)
3rd B.C. Unconventional Gas Technical Forum (2009)
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IC2 complex
3rd B.C. Unconventional Gas Technical Forum (2009)
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Inner-bend margin (base)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Inner-bend margin (top)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Inner-bend margin (top)
also, commonly 2-3 beds
3rd B.C. Unconventional Gas Technical Forum (2009)
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Traction structures at coarse LAD termini

• initially flows strongly stratified
• later less so turbulent and high to low
  concentration
• steep density gradient ? -- turbulence
  suppression
• level of velocity maximum ?

3rd B.C. Unconventional Gas Technical Forum (2009)
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Lateral accretion deposits (LADs) -- origin
Repetitive episodes of equilibrium
disequilibrium
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equilibrium bypass (fine LAD)
disequilibrium deposition (coarse LAD)
(updip) filtering consistent pinchout position
fine-grain LADS inner levee
3rd B.C. Unconventional Gas Technical Forum (2009)
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Channel Inception
3rd B.C. Unconventional Gas Technical Forum (2009)
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IC2 complex (inner-bend levee summary)
250 m
3rd B.C. Unconventional Gas Technical Forum (2009)
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IC2 complex (inner-bend levee summary)
250 m

• inception by erosion

3rd B.C. Unconventional Gas Technical Forum (2009)
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IC2 complex (inner-bend levee summary)
250 m
Local and recurring internal changes in Qs
autoregulation
3rd B.C. Unconventional Gas Technical Forum (2009)
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Outer-bend margin
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Outer-bend margin
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3rd B.C. Unconventional Gas Technical Forum (2009)
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Seismic conceptual models vs. the real world
Saller et al. , 2008
3rd B.C. Unconventional Gas Technical Forum (2009)
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Abreu et al. (2003)
Lateral accretion deposits (LAPs)
-- problematic horizontal scale
3rd B.C. Unconventional Gas Technical Forum (2009)
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Small scale (LADs of a single channel)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Large scale (juxtaposition of discrete channel
fills)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Abreu et al. (2003)
Lateral accretion packages
? instead laterally nested channel fills
3rd B.C. Unconventional Gas Technical Forum (2009)
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Posamentier and Walker (2006)
3rd B.C. Unconventional Gas Technical Forum (2009)
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3rd B.C. Unconventional Gas Technical Forum (2009)
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IC2 complex nested channel-fill complex
1250 m
3rd B.C. Unconventional Gas Technical Forum (2009)
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Conclusions
1. distinct asymmetry of inner vs. outer bend
levee inner -- depositional fine and coarse
LADs outer -- erosional typically fine
grained (older strata)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Conclusions
1. distinct asymmetry of inner vs. outer bend
levee inner -- depositional fine and coarse
LADs outer -- erosional typically fine
grained (older strata) 2. heterogeneity of LAD
f(local and recurring changes in Qs) - system is
internally regulated
3rd B.C. Unconventional Gas Technical Forum (2009)
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Conclusions
1. distinct asymmetry of inner vs. outer bend
levee inner -- depositional fine and coarse
LADs outer -- erosional typically fine
grained (older strata) 2. heterogeneity of LAD
f(local and recurring changes in Qs) - system is
internally regulated (perturbation damped
downflow)
3rd B.C. Unconventional Gas Technical Forum (2009)
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Conclusions
1. distinct asymmetry of inner vs. outer bend
levee inner -- depositional fine and coarse
LADs outer -- erosional typically fine
grained (older strata) 2. heterogeneity of LAD
f(local and recurring changes in Qs) - system is
internally regulated (perturbation damped
downflow) 3. flows are highly stratified
Umax ?
3rd B.C. Unconventional Gas Technical Forum (2009)
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Conclusions
1. distinct asymmetry of inner vs. outer bend
levee inner -- depositional fine and coarse
LADs outer -- erosional typically fine
grained (older strata) 2. heterogeneity of LAD
f(local and recurring changes in Qs) - system is
internally regulated (perturbation damped
downflow) 3. flows are highly stratified 4.
flows are highly confined channels narrow -
stratal discontinuity between inner levee
deposits and channel-fill strata
3rd B.C. Unconventional Gas Technical Forum (2009)
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HIGHLY confined channels -- erosive outer
levee onlap inner levee
1250 m
3rd B.C. Unconventional Gas Technical Forum (2009)
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Deep-water architectural elements
(Posamentier and Kolla 2003)
3rd B.C. Unconventional Gas Technical Forum (2009)
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3rd B.C. Unconventional Gas Technical Forum (2009)
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Thank you