The Sedimentology and Stratigraphy of the Lower Cretaceous (Albian) Viking Formation, Joffre/Mikwan Fields, Alberta, Canada

Abstract

<p>The Joffre/Mikwan field {Lower Cretaceous, Viking Formation) is a long narrow sandbody encased in marine mudstones. The sandbody trends northwest-southeast. Four cross-sections of the area were made, perpendicular and parallel to the sandbody. The data consisted of 12 cores and 185 resistivity logs.</p> <p>Five erosion surfaces are present within the Joffre/Mikwan fields; E1, E2, CM4, CMS and VE4. Generally, the erosion surfaces drop stratigraphically northward. Northward, the erosion surfaces truncate the surface below or cut into the underlying facies.</p> <p>There are two erosion surfaces below the main Viking sandstones, E1 and E2. E1 underlies lower shoreface deposits and E2 underlies middle shoreface deposits, the main Viking sandstones. These two erosion surfaces were formed as a result of sea level fluctuations within an overall transgression. The shorefaces prograded during stillstands within the transgression. These surfaces, E1 and E2 were formed during the transgression which followed the relative sea level drop that created the first valley incision at Crystal.</p> <p>There are two erosion surfaces above the main Viking sandbody, CM4 and CM5. Transgressive surface of erosion CM4 was formed when transgression resumed after deposition of the main Viking sandbody. After this transgression another relative sea level drop created the second incision at Crystal. The transgressive surface of erosion CM5 formed during the subsequent rise.</p> <p>This interpretation improves upon the single incision scheme proposed by Boreen and Walker (1991). It also suggests a correlation of surfaces CM4 and CM5 with the two transgressive surfaces of erosion at Crystal.</p>