<p> The Lower Cretaceous (Albian) Viking Formation at
Harmattan East and Crossfield, Alberta, contains two
regionally extensive erosion surfaces, VE3 and VE4,
separating three allomembers, A-B, D and E. These erosion
surfaces can be mapped over large areas of the Alberta basin
allowing for the creation of a Viking allostratigraphy. </p> <p> The allostratigraphic base of the Viking alloformation
in the study area is informally designated BV. The BV log
marker is overlain by allomember A-B, which in turn is
overlain by the regionally extensive ravinement surface VE3.
The VE3 surface is sharply overlain by allomember D, a
northeastward thinning clastic wedge composed of storm
dominated facies and nonmarine deposits. Allomember D is in
turn overlain by the regionally extensive ravinement surface
VE4. Allomember E, which overlies this unconformity is a
complex succession of coarse grained facies interbedded with
dark mudstones. The upper . part of allomember E is composed
of dark mudstones bounded at the top by a regionally
extensive condensed section (Base of Fish Scales) that
informally marks the allostratigraphic top of the Viking
alloformation in the study area. </p> <p> Viking sedimentation began with the deposition of
basinal and offshore transitional mudstones, siltstones and
sandstones of allomember A-B. A major drop in sea level allowed valleys to incise into these sediments. Nonmarine
and upper shoreface deposits of allomember A-B were eroded
at Harmattan East during the ensuing transgression that
produced the VE3 ravinement surface. A second relative sea
level lowering resulted in northeastward progradation of
allomember D. Renewed transgression modified the older
subaerial erosion surface on top of allomember D, forming the
marine ravinement surface VE4 and the overlying deposits of
allomember E. Multiple stillstands or slow rates of
transgression produced the "steplike" southwestward climbing
morphology on the VE4 surface. Fluvial systems supplied
coarse sediment to each shoreface incision ("step"). During
minor sea level falls, storm and tidal currents reworked
sediment at these shorefaces and also transported sediment
basinward over older "stepped" shorelines forming onlap
markers EO to E5. Continued transgression blanketed the
coarse grained interbeds with offshore dark mudstones
(Colorado Shale). A major pause in basin deposition led to
the formation of a condensed section of fish skeletal remains
(Base of Fish Scales). The base of this unit marks the end
of Viking depostion in the study area. </p> <p> The Harmattan East Viking oil field is producing from
the coarse grained transgressive lag that overlies VE4. It
is separated from Caroline field (along depositional strike)
by a rise in the VE4 surface. </p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/19824 |
| Date | January 1992 |
| Creators | Hadley, Scott |
| Contributors | Walker, R.G., Geology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
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