Abstract

Deposition of the Lower Triassic Sulphur Mountain Formation of Western Canada was the product of a dynamic interaction of sedimentary processes and tectonism, resulting in highly heterogeneous successions. The Sulphur Mountain Formation, age equivalent to the subsurface Montney Formation, outcrops in South Central Rocky Mountains, Alberta, Canada and provides an opportunity for a high-resolution study. A detailed framework of four studied outcrops was established by integrating sedimentology, stratigraphy, and inorganic geochemistry. Four lithofacies were identified in these outcrops; hummocky cross-stratified very fine sandstone (L-1), massive-appearing very fine sandstone and coarse siltstone (L-2), interlaminated very fine sandstone and siltstone (L-3), and planar laminated siltstone (L-4). Interpreted environments of deposition for these lithofacies range from lower shoreface to proximal offshore. Correlated outcrop measured sections and interpretations of the geochemistry and lithofacies suggest a dynamic and complex depositional history. Changes in relative sea level, source terrain/provenance, and detrital clastic sediment input infer depositional influences during intervals of extensive weathering and tectonic activity. These factors provide an explanation for the facies heterogeneity observed in the Sulphur Mountain Formation.