The Co-Occurence of Trypanites and Glossifungites Substrate-Controlled Trace-Fossil Assemblages In A Triassic Mixed Siliciclastic–Carbonate Depositional System: Baldonnel Formation, Williston Lake, B.C., Canada

摘要: Abstract Detailed outcrop analysis of an Upper Triassic, shallow marine, mixed siliciclastic–carbonate ramp succession in northwestern Canada reveals numerous disconformities that are characterized by substrate-controlled trace-fossil assemblages. Although Glossifungites assemblages, and to a lesser extent, Trypanites common the Carnian Baldonnel Formation, several horizons, pattern paired Trypanites–Glossifungites-demarcated discontinuity surfaces occurs. These occur same overall environmental setting interpreted have general stratigraphic implications each case. The invariably lower section. They penetrate into sandy bioclastic limestone infilled overlain coarse-grained detrital lag. Their development indicates early cementation coastal setting. form coplanar maximum regressive transgressive erosion correlatable on regional scale. lags overlain, turn, laminated calcareous siltstone (denoting offshore deposition) sandstone (a return shoreface depositional conditions). siltstone–sandstone contacts low-diversity which as amalgamated storm-induced wave ravinement emplaced front rapidly prograding shoreface. Paired Trypanites–Glossifungites Formation reflect fluctuations relative sea level sediment input low accommodation