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Mapping of the north flank of the Doonerak fenster has traced the Amawk thrust, the sole fault of the Endicott Mountains allochthon, from the North Fork of the Koyukuk River-Mount Doonerak area eastward for more than 40 km (25 mi) to the east plunge of the Doonerak anticline at Koyuktuvuk Creek near the Dietrich River. Mapping has concentrated on the structural style of the area and on the autochthonous or parautochthonous Carboniferous Lisburne Group, Kayak Shale, and Kekiktuk Conglomerate--which are present along most of the anticline--and Triassic Karen Creek Sandstone, Triassic Shublik Formation, and Permian-Triassic Sadlerochit Group--which are present only in the west. This Triassic to Mississippian section closely resembles the coeval autochthonous to parautochthonous Ellesmeri n section of the subsurface to the north and in the Brooks Range to the northeast.

The north-dipping Amawk thrust is mapped between outcrops of lower Paleozoic metasedimentary rocks and this subjacent Triassic to Mississippian section. On the west, an unbroken stratigraphic sequence underlies the Amawk thrust; a complete section of Karen Creek, Shublik, Sadlerochit, Lisburne, Kayak, and Kekiktuk is exposed in the canyon of Bombardment Creek. The Kekiktuk Conglomerate unconformably overlies weathered Ordovician-Cambrian mafic volcanic rocks. Well-developed slaty cleavage in Sadlerochit and Lisburne rocks is compatible with northward-thrust transport of the overlying Endicott Mountains allochthon. East of Bombardment Creek, structural complexity increases markedly, and multiple slivers of Kekiktuk, Kayak, Lisburne, and Sadlerochit are mapped below the Amawk thrust. At Falsoola Mountain, near the east end of the fenster, the Lisburne is isoclinally folded. Near Koyuktuvuk Creek, this parautochthonous section can be described as a broken formation. Movement has occurred along incompetent horizons, particularly within the Kayak Shale, resulting in imbrication of the competent beds. This movement can be interpreted as drag resulting from emplacement of the overlying Endicott Mountains allochthon and not from a regionally significant thrust fault.

Along most of the north side of the fenster, from Mount Doonerak eastward to Falsoola Mountain, east-trending high-angle longitudinal faults uplift the core of the fenster. These vertical to steeply south-dipping faults have vertical separations of a few meters to over 500 m (1,600 ft), and postdate the Early Cretaceous (probably Neocomian) emplacement of the Endicott Mountains allochthon. This uplift was probably related to the Albian and Late Cretaceous tectonic events interpreted elsewhere in the Brookian orogen. Alternatively, the high-angle faults can be interpreted as part of the floor of a duplex. However, there is no evidence of any large amount of horizontal translation along these faults.

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