Abstract An integrated approach, involving nearly all available biostratigraphic data, event and sequence stratigraphy, has been utilized in correlation of the Middle Devonian (latest Eifelian–Givetian) Hamilton Group and equivalent strata in north-central North America. This approach permits high-resolution correlation of strata equivalent to the Oatka Creek (upper Marcellus), Skaneateles, Ludlowville and Moscow Formations from New York into sections bordering the Michigan Basin in Ontario, Canada, as well as southern Michigan, northern Ohio and Indiana, USA. Most member and submember-scale units, herein slightly redefined and interpreted as 3rd and 4th order sequences, respectively, and their bounding condensed beds can be correlated regionally. Moreover, many faunal patterns also persist across this region, which, together with sequence stratigraphy, provides a bridge for correlation into the Michigan Basin. The detailed stratigraphy presented herein permits a more-resolved understanding of far-field tectonics, eustasy and biotic responses during the Middle Devonian. Allocyclic processes, primarily eustasy, played a key role in generating persistent sedimentary cycles. Episodes of rapid mud sedimentation occurred over large areas of the cratonic interior, distal to Acadian source terrains. The major Algonquin–Findlay Arch, which presently separates the Michigan Basin from the Appalachian foreland basin, was not present during deposition of these strata. Conversely, a roughly north–south trending region, running approximately through present-day Cleveland, Ohio, was first a local subsiding area during late Eifelian–early Givetian time and then underwent topographic inversion to form a local arch at which upper Hamilton units were condensed and then bevelled during the later Givetian; we infer that this feature may represent a migrating forebulge. Finally, fossil biotas do not show strong partitioning into Appalachian and Michigan basin faunal subprovinces during the early Givetian, as there appears to have been no physical barrier to migration at least in the study area. However, Hamilton-equivalent strata in the most proximal portion of the Appalachian Basin do show a relatively minor admixture of typical Michigan Basin taxa with normal Hamilton forms.

Abstract The late Eifelian–earliest Givetian interval (Middle Devonian) represents a time of significant faunal turnover in the eastern Laurentia and globally. A synthesis of biostratigraphic, K-bentonite and sequence stratigraphic data indicates that physical and biotic events in the Appalachian foreland basin sections in New York are coeval with the predominantly carbonate platform sections of southern Ontario and Ohio. The upper Eifelian ( australis to ensensis conodont zones) Marcellus Subgroup in New York comprises two large-scale (3rd-order) composite depositional sequences dominated by black shale, which are here assigned to the Union Springs and Oatka Creek Formations. The succession includes portions of three distinctive benthic faunas or ecological–evolutionary sub-units (EESUs): ‘Onondaga’, ‘Stony Hollow’ and ‘Hamilton’. In the northern Appalachian Basin in New York, the boundaries of these bioevents show evidence of abrupt, widespread extinctions, immigration and ecological restructuring. In the Niagara Peninsula of Ontario and from central to northern Ohio, the same sequence stratigraphic pattern and bioevents are recognized in coeval, carbonate-dominated facies. The correlations underscore a relatively simple pattern of two major sequences and four subsequences that can be recognized throughout much of eastern Laurentia. Moreover, the biotic changes appear to be synchronous across the foreland basin and adjacent cratonic platform. However, the degree of change differs substantially, being less pronounced in carbonatedominated mid-continent sections. Finally, we make the case that the two major faunal changes align with regional sequence stratigraphic patterns as well as with the global Kačák bioevents.