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