A PROVENANCE ANALYSIS OF PASSAIC FORMATION FANGLOMERATE FACIES ADJACENT TO THE RAMAPO FAULT, NEWARK BASIN

The Passaic Formation in the Triassic-Jurassic Newark Basin is exposed throughout northern New Jersey, southeastern Pennsylvania, and southeastern New York. This lithologically variable unit includes conglomeratic lithofacies adjacent to the Ramapo Fault that bounds the north and northwest portion of the failed rift basin. These lithofacies represent an alluvial depositional environment in this portion of the basin and accumulated concurrently with predominantly normal fault motion. Here we report on a study of the provenance of these fanglomerate units and their potential source areas. We consider possible sources for the pebble, cobble, and boulder clasts in the Passaic conglomerates as the Precambrian and Paleozoic bedrock units now exposed to the basin’s north and northwest. Our analysis of the border conglomerates may provide a window into the past to understand more about the depositional and environmental history of this region and, potentially, the paleoenvironmental and geomorphological conditions in the clast source region.

Detailed stratigraphic and sedimentological data were collected along a semi-continuous N-S exposure of fanglomerate-sandstone lithofacies north of Milford, New Jersey on Riegelsville/Milford Road along the Delaware River. More than 250 meters of stratigraphic section were measured in shallowly northward dipping strata along a transect that exhibited a general coarsening of conglomerate units north toward the fault. Lithologic variation of component clasts within the conglomerates were estimated and recorded as percentages. Seven clast types have been consistently observed: white/grey quartz/quartzite, oxidized quartz, carbonates, arkosic sandstones, clasts containing abundant quartz veins, and samples containing iron bands. Precambrian metamorphic clasts are uncommon in the measured section. These samples are compared to potential Paleozoic parent materials through hand sample and thin section analysis along with element analysis via SEM-EDS. Analysis of other exposures of the border conglomerates will provide a lateral view of the provenance variability and depositional variability.