High-resolution, single-channel and multichannel seismic-reflection profiles in the New York Bight provide 7 crossings of a 50-km-long fault that trends north-northeast for 30 km from its southern end, then bends northeast, and may continue northward beneath Long Island. Displacement, which is consistently down to the west, decreases upsection and suggests a growth fault. Dip of the fault is near vertical. Its maximum offset of 109 m is the largest offset at the base of the Coastal Plain known for any Cretaceous and younger fault along the East Coast. Seismic stratigraphic controls constrain motion on the fault between Late Cretaceous (95 m.y. B.P.) and middle Oligocene (30 m.y. B.P.). The evidence for Quaternary activity is ambiguous.
The fault parallels a magnetic low to the east, interpreted as a buried Mesozoic rift basin from seismic-reflection data, and a gravity low to the west, interpreted as a structure within Paleozoic rocks from well data. Whether these structures control the location of, or movement on, the fault is not clear.
- Geological Society of America