Lithological and geochemical attributes of ancient deep marine turbidite systems within
the Castle Creek Formation of the Windermere Supergroup
Rachelle Landriau, William Arnott
Department of Earth and Environmental Sciences, University of Ottawa
the Castle Creek Formation of the Windermere Supergroup
Rachelle Landriau, William Arnott
Department of Earth and Environmental Sciences, University of Ottawa
Rocks of the Windermere Supergroup (WSG) records a truly unique part of Earth history, including the break-up of the supercontinent Rodinia, potentially global glaciations, and evidence of metazoan life. Located in the southern Canadian Cordillera the WSG makes up continent-margin turbidite system formed mostly of sediment transported from the North American craton. Here strata are composed predominantly of siliciclastics which are interrupted intermittently by carbonate rich intervals up to 100s of meters thick indicating the activation of an expansive shallow-water carbonate factory, that likely coincided with elevated sea level present in highstand conditions. In addition to these dramatic long term changes (> 1000 m vertically) in the mineralogical makes up of the rocks, are more common and smaller scale (10s to a few 100 m vertically), systematic and recurring changes in stratal-element composition of the sedimentary pile. These suggest repeated changes in the continental sediment supply, which in turn modified the character of turbidity currents that act to remobilizes sediments downslope and built up the stratigraphy. This prompted an investigation into whether these very evident shorter term changes in stratigraphy were recorded in the elemental composition of the strata - more specifically their major, minor and trace element composition. Using X-ray fluorescence samples from three locations, Castle Creek North, Castle Creek South and the Hill Section, were analyzed. The data shows that in spite of being evident in the macroscopic stratigraphic record, small-scale (10s to a few 100 m vertically) changes in elemental composition of the constituent strata changed little and only the large-scale (several 100s to 1000 m upward) changes in elemental composition were detected. This suggests that conditions excluding mineralogy control the stratigraphic depositional record of deep-marine turbidite systems.