Sedimentology, ichnology, stratigraphy and depositional history of the contact between the Triassic Doig and Montney Formations in west-central Alberta, Canada: Presence of an unconformity bound sand wedge.

摘要

In west-central Alberta during the Early (Spathian) Triassic the Moig Siltstone, Moig Sandstone and Lower Doig Formation were deposited. Analysis of core, well logs, cross-sections and maps suggests that these units were emplaced in an overall transgressive system with occasional stillstand deposition. The Moig Siltstone and Moig Sandstone form two unconformity bound sand wedges. Mapping and cross-sections suggests that high energy flooding surfaces influenced morphology of the units. Theses three units studied were also affected by the underlying Paleozoic faults.;From core analysis three facies associations (SO, B, and SS) were developed based on fifteen facies (F1-F11). The three associations relate to sheltered shelf deposits (FA SS), storm dominated upper offshore to transition zone deposits (FA SO), and low energy transition zone to proximal lower shoreface deposits (FA B). Ichnology was crucial in delineating the Moig Sandstone (FA B) since all sedimentary structures had been biogenically altered.