Biostratigraphic evidence for incremental tectonic development of early Cambrian deep-water environments in the Misty Creek embayment (Selwyn basin, Northwest Territories, Canada)

The early evolution of the Misty Creek embayment (MCE), a prominent, northwest-trending sub-basin economically important Selwyn basin, is poorly understood. abrupt contact between Cambrian Stage 4 (traditional lower Cambrian) carbonate ramp strata Sekwi Formation and overlying Miaolingian middle deep-water, calciturbiditic Hess River has been regarded as diachronous. This transition, which marks onset long-lived, deep-water conditions in MCE, remains unexplained. study uses biostratigraphic data from previously undescribed location existing lithostratigraphic 1970s, regional thickness patterns to characterise sharp yet diachronous transition lithofacies typical those Formation. dramatic change depositional environments was non-gradational, precluding eustatic cause. geologically abrupt, probably through two extension-related subsidence events, with different geographic extents, heralded MCE’s long life basin. MCE occurred semi-contemporaneously other events that are recorded northern Canadian Cordillera, demonstrating Series 2 – time widespread extension along western margin Laurentia.