DEEP CRUSTAL REFLECTIONS IN EUROPE

Abstract

Deep crustal reflected arrivals in the near‐vertical and the wide‐angle range have been recorded in various parts of Europe. A high resolution of deep crustal structures can be obtained by special seismic investigations. Reconnaissance surveys may be performed during routine prospecting work by using recording lengths up to 15 sec. Several profiles with multiple coverage and digital processing of the data demonstrate the possibility of obtaining seismic cross‐sections down to the Moho. In addition to near‐vertical reflection work, studies of wide‐angle arrivals at distances up to 150 km and more are most favorable for a calculation of seismic velocities in the deeper crust. Ray‐tracing programs have revealed low‐velocity zones at depths below 10 km in many continental crusts. From comparison of reflected amplitudes in the near‐angle and the wide‐angle ranges and from other observations, a lamellar structure in the deeper crust is often detected. Regional differences of various traveltime branches show characteristic crustal structures. It is shown that deep seismic sounding is useful for estimating the shape and development of sedimentary troughs and their connection to oil‐bearing structures, heat energy, and possible ore deposits.