New constraints on the structure of offshore Mesozoic rift basins and distribution of the Central Atlantic Magmatic Province along the eastern U.S. coastline from high-resolution aeromagnetic and gravity data

The Central Atlantic Magmatic Province (CAMP) basalt formations found in Mesozoic rift basins along the eastern North American seaboard are postulated as the proximate cause of the end-of-Triassic mass extinction event. CAMP volcanism is identified in onshore basins; however, basin structure and CAMP basalt distribution in the offshore New York Bight Basin (NYBB), Long Island Basin (LIB), and Central Bight Basin (CBB) are not well constrained due to the limited resolution of legacy seismic and existing magnetic and gravimetric survey data. Geopotential modeling of new high-resolution magnetic and gravity survey data predicts multiple CAMP basalt flow units equating to a total volume of at least ∼1,100 km 3 in the New York Bight and Long Island basins. Forward modeling and depth-to-source analyses show a possible wedge of igneous material in the Long Island Basin, bordered by NW–SE trending faults that splay off the western border fault. Magnetic sources and strong seismic reflectors at the basement top also indicate interbasinal CAMP volcanism. The extension of a magnetic high from interbasinal areas toward the East Coast Magnetic Anomaly suggests that CAMP volcanism may have formed contemporaneously with seaward-dipping reflectors. These results indicate that offshore CAMP activity may have occurred during and after the main rifting phase in the central North American rift system. This differs from previous findings in the area, where CAMP activity pre-dated the cessation of rifting, thus shedding new light on the development of this passive margin.