Recent, arctic deltaic sedimentation: Olivier Islands, Mackenzie Delta, North‐west Territories, Canada

• Published in: Sedimentology
• Main Authors: JENNER, K. A., HILL, P. R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1998
• Subjects: Stratigraphy; Geology; General Earth and Planetary Sciences; General Environmental Science; Ice; Mackenzie Delta; permafrost; wedge*
• Online Access: http://dx.doi.org/10.1046/j.1365-3091.1998.00193.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-3091.1998.00193.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-3091.1998.00193.x

Despite a low tidal range and relatively low wave conditions, the Mackenzie Delta is not prograding seaward but rather is undergoing transgressive shoreface erosion and drowning of distributary channel mouths. In the Olivier Islands region of the Mackenzie Delta the resultant morphology consists of a network of primary and secondary channels separated by vegetated islands. New ground is formed through channel infilling and landward‐directed bar accretion. This sedimentation is characterized by seven sedimentary facies: (1) hard, cohesive silty clay at the base of primary channels which may be related to earlier, offshore deposition; (2) ripple laminated sand beds, believed to be channel‐fill deposits; (3) ripple laminated sand and silt, interpreted as flood‐stage subaqueous bar deposits; (4) ripple laminated or wavy bedded sand, silt and clay, representing the abandonment phase of channel‐fill deposits and lateral subaqueous bar deposition from suspension settling; (5) a well sorted very fine sand bed, presumed to result from a single storm event; (6) parallel or wavy beds of rooted silt, sand and clay, interpreted as lower energy emergent bar deposits; and (7) parallel or wavy beds of rooted silt and clay, believed to represent present‐day subaerial bar aggradation. The distribution of sedimentary facies can be interpreted in terms of the morphological evolution of the study area. Initial bar deposition of facies 3 and channel deposition of facies 2 was followed by lateral and upstream bar sedimentation of facies 3 and 4 which culminated with the deposition of the storm bed of facies 5. Facies 6 and 7 signify bar stabilization and abandonment. Patterned ground formed by thermal contraction and preserved in sediments as small, v‐shaped sand wedges provides the most direct sedimentological indicator of the arctic climate. However, winter ice and permafrost also govern the stratigraphic development of interchannel and channel‐mouth deposits. Ice cover confines flow at primary channel mouths, promoting the ...