IMPACT ORIGIN OF THE CHESAPEAKE BAY STRUCTURE AND THE SOURCE OF THE NORTH-AMERICAN TEKTITES

Seismic profiles, drill core samples, and gravity data suggest that a complex impact crater similar to 35.5 million years old and 90 kilomet ers in diameter is buried beneath the lower Chesapeake Bay. The brecci a that fills the structure contains evidence of shock metamorphism, in cluding impact melt breccias and multiple sets of planar deformation f eatures (shock lamellae) in quartz and feldspar. The age of the crater and the composition of some breccia clasts are consistent with the Ch esapeake Bay impact structure being the source of the North American t ektites.