The Depositional History of the Lower Cretaceous viking Formation at Joffre, Alberta, Canada

Abstract

<p>Detailed core and log correlations have shown that there are three erosion surfaces within the Viking at Joffre, and that each surface is overlain by unusually coarse sediment. The main sand development at Joffre overlies the E2 erosion surface and comprises cross-stratified, medium-grained to pebbly sandstones. The basal portion of this sandstone tends to be glauconitic. This sandstone is interpreted to be the remnant of a shoreface which developed at Joffre in response to a relative lowering of sea level. Evidence for exposure southwest of the shoreface was removed during the subsequent transgression, as was the upper shoreface and beach. Only the mid to lower part of the shoreface was preserved and blanketted by burrowed marine mudstone.</p> <p>In total, five bounding surfaces have been defined at Joffre, three of them are demonstrably erosive and the other two are designated as core markers. These bounding surfaces serve to divide the formation into six distinct sedimentary packages which tend to coarsen upward. Viking deposition at Joffre appears to have been controlled by fluctuations of relative sea level.</p>