New color display techniques help to interpret deep seismic reflections

Deep seismic reflection data typically sample the entire Earth's crust and usually have reflection patterns different from those of sediments. Continuous reflections over distances longer than a few kilometers are rare, and their amplitudes and dips may vary considerably within a small portion of the seismic section. This makes it difficult to observe consistent trends in the reflections. Such observations are important because the interpretation of deep seismic data relies on consistent reflection patterns that identify tectonic units. For example, Marillier et al. [1989a, b] identified three lower crustal blocks underlying the northern Appalachians in eastern Canada, on the basis of consistent seismic characteristics over several hundreds of kilometers. Another important feature, the crust-mantle boundary, is sometimes difficult to detect because the reflectivity of the lower crust diminishes gradually with depth.