The New Jersey Transect: Stratigraphic Framework and Depositional History of a Sediment-Rich Passive Margin

Abstract

The results from Leg 95 of the Deep Sea Drilling Project bring to completion a series of geological and geophysical studies along a 700-km transect of the New Jersey continental margin. Integration of outcrop, borehole, and seismic reflection data along this transect has revealed the regional stratigraphic framework and has allowed a comprehensive interpretation of the depositional history of the Baltimore Canyon Trough and the adjacent North American Basin. The depositional sequences documented at the boreholes are extrapolated along the grid of seismic profiles to produce isopach maps.Analyses of these data show that sediment dispersal on the New Jersey margin has been governed in large part by sea-level changes, but modified by temporal changes in shelf-edge physiography, sediment sources, and deposition rates. Notable examples include the buildup of a shelf-edge reefal system during the Late Jurassic; its subsequent burial in the Late Cretaceous, as massive turbidity currents and debris flows reached the lower rise; the appearance of a dual shelf-edge system and widespread carbonate production during the Paleogene; rapid progradation of thick deltaic prisms during the middle Miocene; and deep incision of the shelf edge by submarine canyons during the Pleistocene.Massive downslope gravity flows have dominated both the depositional and erosional history of the New Jersey margin during most of the last 135 m.y. The importance of periodic widespread erosion is recorded by correlative unconformities at the boreholes. These unconformities also correlate well with supercycle boundaries of the Vail depositional model, thereby providing field validation of the supercycle framework of the model.

High-Resolution Lithologic Characterization of Sequences on the New Jersey Margin Slope through Inversion of Leg 150 Logging Data for Lithologies

“…While these estimates obviously need refinement, it is immediately clear that the periodicity of these upper Eocene lithologic cycles is far shorter than that usually attributed to tectonic forcings (Vail et al, 1977). This in turn tends to support Poag's (1987) assertion that upper Eocene sediment dispersion on the New Jersey Margin was strongly influenced by glacioeustatic forces.…”

Palynology and Dinocyst Stratigraphy of the Eocene and Oligocene in ODP Leg 105, Hole 647A, Labrador Sea

“…That these species are common at Site 647 and apparently absent from the eastern North Atlantic may suggest an affinity between the south western North Atlantic and Site 647 that is not shared with the eastern North Atlantic. Perhaps the distribution of these species in the North Atlantic and contiguous areas is related to the in tensification of the proto-Gulf Stream that occurred from mid dle Eocene time (Poag, 1987). Dinocyst assemblages from the Oligocene include a cosmopolitan component, together with a number of species that have been recorded from high northern latitudes, suggesting a partial influence of arctic water masses.…”

“…Elsewhere, the early/middle Eocene boundary coincides with an increased surface-water organic productivity and a temperature decrease of 1° to 2°C in both surface and bottom waters of the Atlantic (Kaminski, Gradstein, and Berggren, this volume, and references therein). Hiatuses spanning the early/middle Eocene boundary occur in a number of DSDP sites in the western and northwestern North Atlantic and may be related to an intensifi cation of the proto-Gulf Stream and a decrease in eustatic sea level (Poag, 1987), which may in turn be related to a reduction in the rate of seafloor spreading in the North Atlantic and Lab rador Sea (Miller et al, 1987;Kaminski, Gradstein, and Berg gren, this volume). At Site 647 the hiatus is not defined precisely by calcareous microfossils as these are absent across the bound ary.…”

Stratigraphy of the Eocene Chalks Recovered from the New Jersey Margin, Leg 150: Synthesis

“…The oldest occurs in Core 150-904A-60X, but the contact between the upper lower or lower middle (Subzone NP14a) and middle (Subzone NP15b) Eocene chalks was not recovered. Unconformable contacts in the same interval have been described from other sections on the New Jersey Margin, at such offshore sites as DSDP Sites 605, 612, and 613 Wise, 1987a, 1987b;Poag and Low, 1987;Aubry, 1991) and onshore sites such as the AGCS #4 well (Miller et al, 1990;Aubry, 1991) and the Island Beach well . The next obvious unconformity separates either middle (Zone NP16) from upper Eocene (Zone NP18) chalks or middle Eocene (Zone NP16) from middle Eocene (Zone NP17) chalks.…”