Hydrogeologic Framework of Investigation Sites in the Newark Basin Using Geologic Formations, Members, and Cyclic Deposit Stratigraphy

Groundwater investigations at sites within the Mesozoic Rift Basins of eastern United States generally describe and display the site strata as part of a single geologic formation. The three major geologic formations in the Newark Basin of New Jersey and Pennsylvania (Stockton, Lockatong and Passaic) collectively are about 4,500 meters thick. The Lockatong and Passaic formations are divided into 51 Members based on McLaughlin cycles. Each member is 40 to 100 meters thick and laterally extensive for tens of kilometers. Members are composed of about 20 Van Houten cycles with individual strata ranging from 0.2 to 5 meters thick.  As part of hydrogeologic framework development for groundwater investigation sites, the Formations are subdivided into member and cyclic strata which permits advanced understanding and interpretation of the hydrogeology and geochemistry of both the site and the Newark Basin.

The USGS Toxics Substances Hydrology Research Program uses the cycle subdivisions of the Lockatong Formation to define the hydrogeologic framework at the Naval Air Warfare Center (NAWC) fracture rock research site in the investigation of remediation issues dealing with chlorinated solvents in fractured bedrock aquifers.  The USGS used cyclic subdivision in the Passaic Formation to define the hydrogeologic framework at three  solvent contamination sites and also for investigations of naturally high arsenic- and uranium- bearing water zones from  both formations. 

Fissile and indurated strata within the cycles generally are water bearing or semi-confining units, respectively, near land surface and become non-water bearing strata at depths greater than 150 meters. Mapping the surface and subsurface extent of the 51 members of varying lithology and hydrogeologic properties has the long-term potential to enable evaluation of the fate and transport of groundwater contamination, the contributing area to supply wells, and the exclusion of strata with high contents of natural contaminants for use as potable water source.