AAPG Bulletin, V. 82 (1998), No. 5A (May 1998 Part A), P. 729-756.

High-Resolution Sequence Stratigraphy of Early Transgressive Deposits, Viking Formation, Joffre Field, Alberta, Canada¹

James A. MacEachern,² Brian A. Zaitlin,³ and S. George Pemberton⁴

©Copyright 1998.  The American Association of Petroleum Geologists.  All Rights Reserved

¹Manuscript received April 8, 1996; revised manuscript received March 19, 1997; final acceptance November 14, 1997.
²Earth Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
³PanCanadian Petroleum Ltd., P.O. Box 2850, Calgary Alberta T2P 2S5, Canada.
⁴Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E3, Canada.

This paper derives from a postdoctoral project undertaken by MacEachern, in collaboration with Zaitlin and Pemberton, as part of Natural Sciences and Engineering Research Council (NSERC) Collaborative Research and Development (CRD) grant 180563 awarded to S. G. Pemberton. The data were collected while MacEachern was engaged at PanCanadian Petroleum Ltd. We would also like to thank PanCanadian Petroleum Ltd. for their financial and logistical support throughout the course of this study. This project could not have been completed were it not for the valuable assistance of Yan Liu, Pat Allan, Jeff Peterson, Andre Politylo, Don McPhee, and Rolly Jameus. The project benefited from discussions with Lee Krystinik, Ron Boyd, Bob Dalrymple, Dale Leckie, Bill Arnott, Roger Walker, Ed Clifton, Janok Bhattacharya, John Suter, Indraneel Raychaudhuri, Jeff Peterson, and Bruce Power. We also would like to acknowledge the excellent and thorough formal reviews by John Van Wagoner, Frank Etheridge, and John Anderson, as well as the informal reviews by Bob Dalrymple, Roger Walker, Andy Pulham, and Bruce Tocher. The paper benefited greatly from their insights, comments, and suggestions. 

ABSTRACT

The Lower Cretaceous Viking Formation of the Joffre field is characterized by complex reservoir architecture. Deposits of three discrete sequences were delineated using high-resolution sequence stratigraphy. The coarse-grained deposits of sequence 3, lying between BD-2 and an overlying open marine flooding surface, comprise the main reservoir interval within the Viking Formation of the Joffre field. This succession has previously been interpreted as an incised conglomeratic shoreface, stranded in a basinal position during transgression; however, sequence 3 displays characteristics difficult to reconcile with a shoreface interpretation, including an abundance of brackish mudstone interbeds and rip-up clasts, dominance of trough cross-stratification in the coarse clastics, and large-scale interfingering of the coarse clastics with fine-grained marginal-marine deposits. Despite the incised basal contact and brackish-water characteristics of the deposits, the succession does not reflect an estuarine incised valley complex, as conventional sequence stratigraphic wisdom might suggest. The shore-parallel orientation of the deposit, the lack of a convincing valley margin to the northeast, and parasequence orientations lying parallel to the strike of the deposit are inconsistent with an incised valley interpretation. Instead, the succession is interpreted as a broad brackish-water embayment of the shoreline, into which coarse-clastic bayhead delta and distributary channel complexes were deposited during incremental transgression. Such lagoonal or brackish bay complexes are ubiquitous in modern transgressive shorelines, but previously have been recognized only rarely in the ancient record.