A DETAILED GRAVITY MAP OF THE NEWARK BASIN IN EASTERN PENNSYLVANIA

As part of a project to create a gravity map of Pennsylvania, we have been compiling gravity data from various sources including the National Geophysical Data Center and other academic sources. In addition, we have collected new gravity data in eastern Pennsylvania as part of various research and thesis projects. The current endeavor focuses on obtaining a detailed and well-distributed set of gravity data over the Pennsylvania portion of the Newark basin, one of a series of rift basins along the eastern margin of North America created by the rifting of Pangaea during the Late Triassic and Early Jurassic. These basins were filled with cyclic, continental lacustrine sediments and intruded by a series of tholeiitic diabase sills.

Over 300 new gravity readings have been taken to fill in the gaps between existing observations. These data have been corrected for compatibility and integrated into one large database. The first goal of the project is to produce a comprehensive Bouguer gravity map of the Newark basin and marginal areas. In addition, trend-surface analysis will be performed to determine the effect of deep-seated structures, while residual (or high-frequency trend-surface) analysis will help to isolate near surface features. The higher density of data will allow us to construct more detailed models of the intrusives in the basin. In addition we will be able to refine our existing structural models of the character of the western border fault and see if it changes along strike.

We will present a series of maps documenting the spatial relationship between the gravity anomalies and known surficial structures as well as models of the subsurface structure of the sills and basin margin. The long-wavelength (regional) and short-wavelength (residual) maps will be used to help highlight specific structural features.