Identifying basaltic flows and sills in buried Mesozoic rift basins along the eastern US seaboard using seismic interpretation and geopotential modelling

SUMMARY Basaltic flows and sills of the Central Atlantic Magmatic Province (CAMP) along the eastern North American seaboard have been proposed to be present in buried Mesozoic basins. Their offshore distribution is poorly constrained, yet the strong magnetic and gravity signature produced by basaltic rocks means it should be possible to map them using magnetic and gravity surveys. We conducted forward modelling using existing magnetic and gravity data to identify Mesozoic basins and basaltic units offshore. Onshore and offshore basins containing CAMP basalts in forward models generally predict the best fit with observed magnetic and gravity data. A positive magnetic anomaly over the New York Bight Basin suggests it may contain multiple basalt flows at depths > 2500 m, and scenario testing indicates the Long Island Basin possibly hosts at least one flow. The newly identified Central Bight Basin is unlikely to contain basaltic units, although the adjacent East Coast Magnetic Anomaly may be overwhelming potential basalt signatures within the basin. Deeper basement structures and/or possible interbasinal basalt likely influence existing data, therefore higher resolution aeromagnetic and marine gravity surveys are needed to constrain CAMP basalt presence in offshore basins.