FLUVIAL SYSTEMS OF THE PASSAIC FORMATION, NEWARK BASIN, NJ AND PA: THE ROLE OF ANASTOMOSED STREAM DEPOSITIONAL SYSTEMS

The sediments of the Newark Supergroup, especially those from the Newark Basin, contain a record of cyclic deposition at multiple frequencies. Although many research efforts have studied the character of lacustrine sediments in the Newark Basin, relatively little is known about the fluvial systems that carried water and sediments to its lakes. Locally, fluvial sediments can be quite coarse grained and channelized, and are believed to represent deposition in coarse-grained braided systems, notably in the Stockton Fm. and portions of the Passaic Fm. There is little or no evidence of significant meandering stream deposition. However, there are many relatively fine-grained, thin-bedded sandy fluvial deposits that show little evidence for channeling and amalgamation. Rather, these systems are predominantly aggradational, and channels are relatively low relief, shallow, and broad in nature. The system evolves through local nodal avulsion and the construction of crevasse and terminal splays. Measured sections and photopans reveal aspects of the architecture and superposition that define these fluvial packages. Anastomosed systems have a fundamentally different architecture from braided and meandering systems, resulting in different reservoir and aquifer properties. Such deposition is consistent with deposition in anastomosed fluvial networks, similar to those of the Okavango Delta in Botswana. That basin is a rift basin and a structural half-graben at roughly 20 degrees south, extremely similar in style and geography to the ancient Newark Basin configuration. As such, the Okavango may serve as a general analog for the fluvial members of the Passaic Formation in terms of hydrololgy and architectural evolution.