HYDROSTRATIGRAPHY OF THE NEW JERSEY COASTAL PLAIN: SEQUENCES AND FACIES PREDICT CONTINUITY OF AQUIFERS AND CONFINING UNITS

The regional extent and connectivity of Cretaceous to Miocene aquifer sands in the New Jersey Coastal Plain are evaluated using detailed facies analysis within a sequence stratigraphic framework. We correlate sequences from continuous coreholes using well logs to trace across strike and dip sections throughout this region, allowing us to predict the continuity of confining units and aquifer sands. Marine sequences follow a predictable shallowing upward pattern: fine-grained shelf and prodelta sediments grade upward into delta front and shallow-marine sands, corresponding to confining bed-aquifer couplets. Aquifer sands deposited in marine shelf environments tend to be continuous on the 10+ km scale and are traceable for >60 km along strike and >25 km along dip. Confining beds for these units are typically shelf or prodelta silty clays that are even more laterally continuous. Marginal marine to non-marine sequences are more difficult to predict due to a lack of continuous marine marker beds, difficulty in interpreting paleoenvironments of thick sand beds, and lack of fossil material for biostratigraphy except pollen. Marginal to non-marine sequences are generally less continuous, though some show surprising lateral continuity along strike (>60 km), reflecting the widespread extent of delta front environments. We conclude that sequence stratigraphy provides a predictive framework for aquifers and confining units in this and other regions, but that regional and local differences in sediment supply and tectonics affect the development of the hydrostratigraphic framework.