2. LITHOSTRATIGRAPHY AND PALEOENVIRONMENTS OF THE ISLAND BEACH BOREHOLE, NEW JERSEY COASTAL PLAIN DRILLING PROJECT1James P. Owens,2 Kenneth G. Miller,3,4 and Peter J. Sugarman5 |
ABSTRACTWe present lithostratigraphic and paleoenvironmental interpretations of the Island Beach borehole. This borehole provides the only Upper Cretaceous to lower Eocene section recovered by the New Jersey Coastal Plain Drilling Project (Ocean Drilling Program Leg 150X). Upper Cretaceous and Paleogene sections were deposited in relatively deep marine paleoenvironments (typically outer middle to outer neritic; 50-200 m paleowater depths) as a series of upsection shallowing sequences. Although the Oligocene section is relatively thick (267 ft [81.4 m]), it is poorly fossiliferous and provides the most equivocal Oligocene paleoenvironmental record of the three Leg 150X boreholes. Lower Miocene strata at this site consist of three poorly fossiliferous sequences (Kw1a, K1b, and Kw2a) deposited in shallow marine (inner neritic, near-shore, prodelta, and delta front) to fluvial environments. The Miocene sections also shallow upsection, both within sequences and within the Miocene as a whole. The surficial strata at Island Beach are composed of uppermost Pleistocene (?) to Holocene deposited as one deepening-upward succession representing fluvial to near-shore deposits. Tectonics progressively reshaped the basins in which Upper Cretaceous to Holocene strata were deposited. For example, Oligocene basins were mainly in southern New Jersey (Atlantic City and south), whereas the early Miocene Kirkwood basin was more expansive both updip and along strike to the north. Tectonic changes resulted in differential beveling of stratigraphic units and preferential preservation. For example, the lower Oligocene appears to be truncated north of Mays Landing, NJ, and is poorly represented at the Island Beach borehole. |
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