Abstract

The CPOG Kugaluk N-02 well drilled east of Inuvik (the northern Mackenzie River valley) preserves an essentially complete stratigraphic record of the Devonian Landry Formation. Detailed examination of the core demonstrates that the contact between the Landry Formation and the overlying Headless Formation is gradational and conformable, recording upward deepening. The Landry Formation is 216 m thick and composed of characteristic metre-scale peritidal T-R sequences. The highstand end of the facies spectrum is composed of shallow-subtidal fossiliferous packstones, grainstones, and minor tabulate-coral boundstones. The shallowest marine parts of sequences are notably thick (30% of the total succession) and represented by laminated tidal-flat calcimudstones, calcisiltites, and birds-eye dismicrites with occasional supratidal brecciation. Rooted and synsedimentary pedogenized palustrine calcimudstones are recognized in initial-transgressive parts of sequences. The sequences are bounded by disconformities with paleokarst profiles of different depths and degree of host-rock weathering. The log combining lithofacies and subaerial exposure profiles reveals hierarchical 4th to 5th order cyclicity with inferred amplitudes of sea-level fluctuations ranging between 10 and 20 metres. This high-frequency cyclicity may have glacioeustatic origin, which is consistent with the relatively cool (22°C in average) surface tropical waters of the late Emsian–Givetian Ocean. The base of the Landry Formation is gradational and spatially diachronous, defined by a downward increase in dolomite content and limestone-dolostone interbedding. A thick paleosol near the base of Landy Formation may have potential for regional allostratigraphic correlations.

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