Sedimentology of the Viking Formation at Crystal Field, Alberta

Abstract

<p>The Crystal field is found in townships 45 and 46 in the ranges 3 and 4WS. The field differs from other Viking fields by being smaller, thicker, elongate in a north-south direction, and is conglomeratic.</p> <p>Cross-sections of the well logs and lithologs show four extensively bioturbated, sandier-upward cycles that occur on a regional scale in the study area. The cyclic nature of these sediments may be due to distant, unknown aggrading shorefaces, possibly associated with minor relative sea level fluctuations. At Crystal, the cycles are cut out at various levels by an asymmetrical erosion surface. In the west-central area of the field there are two possible surfaces that may be equivalent to the main erosion surface. All of the erosion surfaces have been interpreted as being bases of incised shorefaces. The shoreface movement may be due to fluctuations in the relative sea level.</p> <p>In the western side of the field, lithologs show the sand above these erosion surfaces as being predominantly laminated with a low-angle of inclination and/or laminated that grades into bioturbated tops. Toward the eastern side of the field, the sand gradually becomes more cross-bedded and pebble-rich. The sediment above the erosion surfaces is interpreted as preserved upper to mid shoreface deposits.</p> <p>The top of the Viking at Crystal may be another erosion surface due to a major transgression.</p>