We analyzed specimens of mixed planktonic foraminifer species for Sr isotopes from the Oligocene to middle Miocene sections from boreholes (Ocean Drilling Program Sites 902, 903, 904, and 906; ASP-14, -15) and outcrops on the New Jersey continental slope. We concentrated on the upper Oligocene–middle Miocene at Sites 903 and 904 (444 and 1129 m present water depth, respectively), the upper Oligocene–lowermost Miocene at Site 902 (811 m water depth), and slope outcrops in Carteret and Lindenkohl canyons. Sr-isotopic age estimates of the Ocean Drilling Program boreholes provide a good stratigraphic framework for upper Oligocene to middle Miocene sections, overcoming problems with rare calcareous plankton zonal markers. When integrated with ongoing biostratigraphic and magnetostratigraphic studies, the Leg 150 sites will provide a precise chronology of slope reflectors that also correlate with sequences boundaries traced under the continental shelf. Preliminary integration is encouraging: (1) nine of the 10 Oligocene to middle Miocene slope reflectors (sequence boundaries) correlate with global delta¹⁸O increases and with sequence boundaries in the onshore New Jersey coastal plain, arguing for a causal link between formation of sequence boundaries and glacioeustatic lowerings; and (2) several hiatuses on the slope also correlate with reflectors and the major delta¹⁸O increases, although many of the seismic reflectors appear to be conformable at the slope boreholes. Outcrop studies date a major change in depositional regime in the earliest Oligocene; this "siliciclastic switch" from an Eocene carbonate ramp to a starved siliciclastic early Oligocene margin correlates with a global delta¹⁸O increase and a regional cooling. Sediment starvation in the early Oligocene resulted in a poorly preserved record on the slope.
  Sedimentation rates subsequently increased in the middle Oligocene on the entire margin, when prograding clinoforms appeared beneath the modern shelf and rates increased again in the early to middle Miocene. We attribute this progradational change to lower long-term sea level, although hinterland tectonics may have played an important role.

Date of initial receipt: 22 February 1995
Date of acceptance: 29 August 1995

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