The primary objective of this project is to determine the thermal history of the Newark Basin via fission-track and 40Ar/39Ar analysis of sediment core from the Newark Basin Scientific Drilling Project and surface samples together with some geophysical modeling of the basin evolution. The principal investigators will undertake about 75 fission-track analyses consisting of both surface and subsurface samples. The vertical sections provided by the wells will provide geothermal gradient restraints and data from the intermediate age rift sediments whose outcrop distribution is poor. The surface samples will densify the regional age distribution and detail the recharge zone for hydrothermal circulation identified along the border fault by their earlier work. In addition to the fission-track analyses, approximately a dozen samples will be subjected to 40Ar/39Ar analysis. These samples will include Newark Basin clastics (surface and subsurface), granophyres from the Palisades Sill, and basement rocks adjacent to the Newark Basin. These will provide a higher-temperature framework with which to evaluate the fission-track data. In order to decipher the fission-track data, the principal investigators will numerically model the apatite age and track length distributions to invert for the temperature history of each sample. These estimates of the cooling history will be combined to determine the low temperature thermal evolution of the Newark Basin. The zircon and sphene fission-track ages will help to constrain the higher temperature thermal history.
