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Abstract

During the Early Mesozoic, tectonic activity caused the breakup and separation of the North American and African continental plates, initiating the opening of the Atlantic Ocean. This process is generally referred to as rifting, but there was a strong component of strike-slip movement associated with transform faults (Manspeizer, 1981). Wrench-faulting (Bain, 1977) led to the formation of a series of rhomb-shaped half-grabens or pull-apart basins in eastern North America, which filled with continental sediments during the Late Triassic and Early Jurassic. The distribution of sediments within these basins was strongly controlled by tectonic setting. Coarse clastics were deposited in alluvial fans adjacent to faulted basin margins, and broad alluvial plains developed across the basins. Fine-grained, organic-rich sediments accumulated in large lakes, where subsidence was greatest. Deltas formed where rivers entered the lakes, and coal swamps were present locally in some of the basins. In some basins, subaqueous fissure flows of tholeiitic basalt erupted during the Jurassic. Early Mesozoic fault-bounded basins extend from Nova Scotia to southern Georgia, and are referred to as the Newark rift system. Twenty basins are exposed (Figure 1), and the others are buried beneath post-Jurassic sediments of the Atlantic and Gulf coastal plains, and continental shelf. The rocks in the exposed basins belong to the Newark Supergroup; those in the subsurface are generally considered to be coeval, but they are poorly understood, and apparently of diverse lithology, age and origin (Froelich and Olsen, 1984, 1985). The Deep River basin is the southernmost of the exposed rift

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