8. DATA REPORT: THE OLIGOCENE SEWELL POINT AND ATLANTIC CITY FORMATIONS, NEW JERSEY COASTAL PLAIN1Stephen F. Pekar,2 Kenneth G. Miller,2,3 and Richard K. Olsson2 |
ABSTRACTWe formally name the Sewell Point and Atlantic City Formations, two distinct Oligocene lithologic units identified in subsurface strata in New Jersey. These formations are stratotypified at the Ocean Drilling Program Leg 150X Atlantic City and Cape May boreholes. The lower to upper Oligocene Sewell Point Formation consists of glauconitic clays and silts and clayey glauconite sand. It can be differentiated from the underlying clays of the Absecon Inlet Formation (upper Eocene) by its coarser grain size. The upper Oligocene Atlantic City Formation consists of medium- to coarse-grained glauconitic quartz sands and subordinate glauconitic clays and silts that overlie the Sewell Point Formation. It can be differentiated from the Sewell Point Formation by its coarser grain size, especially its high medium to coarse quartz sand content (>10%, with typical values of ~50% vs. trace amounts in Sewell Point Formation). The glauconitic Atlantic City Formation is readily differentiated from overlying quartz sands and micaceous silty clays of the Kirkwood Formation. Of the six Oligocene sequences recognized in the subsurface by integrated stratigraphy, four (1-4) are restricted to the Sewell Point Formation, whereas two (O5, O6) span both formations, emphasizing the differences between these lithostratigraphic and sequence stratigraphic units. |
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