The objective of this proposal is to continue current processing and interpretation of 5 Gbytes of land-sea wide-angle reflection/refraction seismic data recorded in an expanding spread configuration of the 1986 GLIMPCE project in Lake Superior. The specific geophysical objectives are: (1) to extract, identify, and analyze events returned from Moho and sub-Moho depths, to test the correlation between the reflection and refraction Moho for both P & S phases, (2) to examine the nature of seismically transparent and layered crust at the crust-mantle boundary, and (3) to determine the seismic velocity structure within the Keweenawan rift. The more geological objectives are to determine: (1) the evolution of the Keweenawan rift, (2) if true oceanic crust exists along the rift's axis, (3) if there is a true continent/ocean boundary, and (4) a comparison of these results with modern rifts.
