This paper reports the structural and stratigraphic history of Buck Mountain, Nevada, and its regional significance in the development of southwestern Laurentia during the late Paleozoic. The two distinct generations of folding have similar style and/or timing to other fold sets in late Paleozoic strata of northern Nevada. Unconformities in the upper Paleozoic strata at Buck Mountain are consistent with unconformities documented in northern and east-central Nevada. Northwest-vergent folds (F 1 ) in the Morrowan–Atokan Ely Limestone are erosionally truncated and unconformably overlain by the middle Desmoinesian Hogan Formation and middle Wolfcampian (Sakmarian) Upper Strathearn Formation. This upper Paleozoic stratigraphic package was subsequently refolded by the Buck Mountain Syncline and associated mesoscale folds (F 2 ). F 2 folds lack tight age control but are interpreted to be associated with the Cretaceous central Nevada thrust belt. Critically, none of these structures are localized above or below low-angle faults. The unconformity between the Ely and Hogan formations is consistent with the C5 regional unconformity. Importantly, it constrains the age of northwest-vergent deformation on Buck Mountain. West-vergent folds and west-directed thrusts are documented at several locations in northern and east-central Nevada, but because of the dominance of the C6 unconformity and/or lack of robust age control, the age of these structures has not been tightly constrained. The evidence at Buck Mountain indicates that west-vergent structures predate the C5 unconformity. Buck Mountain is important because it: (1) precisely brackets the age of west-vergent deformation in Nevada to pre–mid-Desmoinesian (sub C5-unconformity) and (2) defines a southeastern edge to the late Paleozoic west-vergent deformation in northern and east-central Nevada.

The stratal architecture of the upper Ely Limestone and Mormon Gap Formation (Pennsylvanian–Lower Permian) in west-central Utah reflects the interaction of icehouse sea-level change and tectonic activity in the distal Antler–Sonoma foreland basin. Nineteen stratigraphic sections correlated by physical and biostratigraphic means provide a basis for tracing Carboniferous–Permian boundary strata over a north–south distance of 60 km. These formations can be subdivided into 14 unconformity-bounded, third-order depositional sequences of differing internal architecture and regional extent. Conodonts and fusulinids provide ages for selected sequences and parasequences, permitting correlation with tectonostratigraphic units in the proximal foreland in north-central Nevada and with selected Midcontinent cyclothems. The 14 third-order sequences stack into three second-order supersequences characterized by distinctive differences in facies and facies stacking patterns, regional continuity of cycles, relative abundance of dolomite and limestone, calculated rock accumulation rates, and the frequency and inferred duration of sequence-bounding hiatuses. These reflect the effect of high-frequency sea-level change on an intermittently subsiding distal foreland shelf. Sediment accommodation was relatively high during the Bashkirian through middle Moscovian (upper part of Lower Absaroka I supersequence) and again during the late Sakmarian and Artinskian (lower part of Lower Absaroka III supersequence) as a function of continuous subsidence and high-amplitude sea-level change. During the late Moscovian through upper Sakmarian (Lower Absaroka II supersequence), however, subsidence slowed or ceased in response to tectonic activity in north-central Nevada, with concomitant development of the West-Central Utah Highlands (forebulge). During this episode of reduced subsidence, intermittent sedimentation was driven by second- and third-order eustatic fluctuations in sea level. Constituent strata form a wedge of onlapping, northward-thinning sequences and parasequences deposited during selected third-order highstands of the Lower Absaroka II second-order sea-level event. Depositional sequences in the distal foreland are bounded by low-relief disconformities of variable duration, in contrast to the angular unconformities and intensely deformed tectonostratigraphic domains that characterize the proximal foreland basin in north-central Nevada.