Ichnological and Sedimentological Comparison of Wave- and River-Dominated Deltaic Deposits from the Lower Cretaceous Kamik Formation in the Parsons Lake Field, Mackenzie Delta Region, Northwest Territories, Arctic Canada
Michael D. Hearn and S. George Pemberton
University of Alberta, Edmonton, AB
The Lower Cretaceous Kamik Formation of the Mackenzie Delta region is interpreted to represent a moderately storm-dominated deltaic succession. Detailed ichnological and sedimentological analysis indicates that the Kamik Formation was deposited as a series of prograding delta lobes characterized by varying degrees of wave, storm and fluvial influence. Overall, wave- and storm-energy were the dominant processes influencing deposition, however some successions also display evidence of a strong riverine influence.
The wave-dominated deltaic successions of the Kamik Formation are comparatively sandstone-rich and are characterized by an abundance of wave- and storm-generated structures, such as hummocky and swaley cross-stratification. This contrasts with the river-dominated deltaic successions, which contain sedimentary structures that indicate high sedimentation rates, substrate instability and minimal degrees of wave reworking. Ichnologically, the wave-dominated deltaic successions are characterized by low to moderate diversity trace fossil assemblages, diminutive morphologies and sporadic distribution of burrows. The river-dominated successions exhibit very low diversity assemblages with many intervals characterized by a complete absence of biogenic structures. Variations in ichnological diversity, abundance and trace fossil morphology are attributed to the numerous biological stresses present in deltaic environments, including high and/or fluctuating sedimentation rates, salinity fluctuations, unstable substrates, high water turbidity, low oxygen levels, light and temperature variations.
Detailed ichnological and sedimentological analysis is key to understanding the dynamic interplay between wave and riverine processes in deltaic systems. The integration of this data provides an effective tool in differentiating between wave- and river-dominated successions and predicting the geometries of ancient deltaic deposits.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005