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Deep Sea Drilling Project Hole 603B, the first deep (1,585 m, 5,200 ft) penetration of the lower continental rise off the eastern United States, intersected an extensive (218 m, 715 ft) Lower Cretaceous deep-sea fan complex. Drilled 435 km (270 mi) east of Cape Hatteras, North Carolina, about 320 km (200 mi) seaward of the Lower Cretaceous shelf break, the continuously cored Hauterivian to Barremian turbidite sequence consists of 47% terrigenous sand. The sand turbidites are generally poorly consolidated and porous except where locally cemented by calcite. The sands appear fresh and are dominated by subangular quartz with abundant feldspar, mica, heavy minerals, wood fragments (locally up to 20%), glauconite, and shallow-water bioclastics. The turbidites exhibit the entir range of Bouma textures and include plastically deformed blocks of sediments up to 25 cm (10 in.) across which indicate channelization and slumping within the fan. Interbedded with the sand turbidites are pelagic limestones and black claystone turbidites, the latter containing up to 13.6% organic carbon in overlying units.
The relatively immature micaceous sands were apparently derived from deep erosion of the piedmont which fed large deltas that prograded across the continental shelf at several points along the central eastern seaboard. There they overwhelmed the fringing reef/carbonate bank and spilled their loads into the deep sea. Coeval deltaic or fan deposits within the circum-North Atlantic (for example, Wealden beds of England or DSDP Site 370/416 off Morocco) suggest either that eustatic sea levels were not rising appreciably (as is generally believed) or that there was synchronous or coincidental uplift and drainage diversion in these various areas.
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