9406006 Boyer This collaborative project will test the generally accepted critical wedge theory for the development of fold and thrust belts, by an integrated field and laboratory study of rocks in the Lewis thrust sheet in northwest Montana. According to the theory, strain should vary within the thrust belt as a function of the geometry of the sedimentary prism. The stratigraphy of the area is well known and lends itself to a test of the model. The geometry of the pre- deformational Proterozoic, Paleozoic and lower Mesozoic sedimentary basins will be determined and the amount and distribution of strain will be compared with that predicted by the model. Whether the existing theory is upheld or not, the results will have far- reaching significance for other fold and thrust belts, and for the prediction and recovery of oil and natural gas reserves in similar tectonic settings.
