Outcrop Characterization of a Deep-Water Channel Complex Set: Isaac Channel 1, Neoproterozoic Isaac Formation, Windermere Supergroup, Canada

Navarro, Lilian L.¹, R. William C. Arnott¹ (1) University of Ottawa, Ottawa, ON

Isaac Channel 1 (IC1) of the Windermere turbidite system is a 200 m thick, base-of-slope channel complex set that is exposed laterally for more than 3 km, although only 1.1 km was mapped in this study. IC1 comprises two vertically-stacked channel complexes that individually consist of several channel fills. Within each channel complex, channel-form elements represent ~70-80% of the stratal volume, and locally are separated by thin-bedded sheets. These sheets are composed of thin-bedded, very-fine sandstone/mudstone strata and record abandonment phases of the channel system.

The most common channel-form elements consist generally of amalgamated and semi-amalgamated strata. Amalgamated strata typically occur in the lower part of the channel complex, whereas semi-amalgamated strata are common in the middle and upper parts. High net-to-gross amalgamated strata consist of normally-graded conglomerate and sandstone. Mudstone-clast breccia are common in the axes of the channel-form element. Semi-amalgamated strata, which have intermediate to high net-to-gross ratios, are characterized by normally-graded sandstone interbedded with thin-bedded, fine-grained (upper-division) turbidites. Toward the channel margins, coarse-grained beds become more interstratified with fine-grained facies. The upward and lateral facies change from amalgamated to less-amalgamated strata is linked to temporal and spatial variations in sediment load and flow characteristics. A rare accretionary architectural element occurs in the uppermost part of IC1, and comprises lateral-accretion deposits overlain by non-amalgamated, thinly-bedded, heterolithic channel-fill deposits. The accretionary element suggests an upward increase in channel sinuosity prior to the final deactivation of the channelized system.

This characterization of the internal architecture of IC1 provides an important analog for slope channel reservoirs.