SEAWARD-DIPPING REFLECTORS OFFSHORE THE SOUTHEASTERN UNITED-STATES - SEISMIC EVIDENCE FOR EXTENSIVE VOLCANISM ACCOMPANYING SEQUENTIAL FORMATION OF THE CAROLINA TROUGH AND BLAKE PLATEAU BASIN

Deep-penetration multichannel seismic reflection profiles off the sout heastern United States reveal widespread seaward-dipping reflectors (S DRs). Similar features have been imaged and sampled on other North Atl antic rifted margins, where voluminous volcanism has accompanied conti nental breakup. Beneath the Carolina trough are two sets of SDRs, one along a basement hinge zone and another seaward of the East Coast magn etic anomaly axis. The hinge SDRs lie beneath, and apparently develope d prior to, a flood basalt that erupted at 184 +/- 3 Ma and is marked by a prominent reflector, J. Beneath the northern Blake Plateau basin, only the hinge SDRs are observed, but they developed after J. We sugg est that the inferred north-to-south age difference of SDR emplacement implies a heretofore unrecognized time-transgressive breakup of north west Africa and North America during the early Middle Jurassic.