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Deep Geology of the Continental Crust from Seismic Prospecting
- Source: First Break, Volume 1, Issue 4, Apr 1983,
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- 01 Apr 1983
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Abstract
Since the 1960s there has been an increasing interest in a more detailed knowledge of the lithospheric structure. The contribution of the improved techniques of geophysical exploration to these developments has been outstanding, the seismic prospecting methods having a primary role. The need for the search for more regional and deeper targets is no longer of purely scientific nature; the exploration of the fine structure of the Earth 's crust and upper mantle has medium- and long-term objectives of practical interest, such as a better understanding of where and how energy and mineral resources accumulate, or where and how earthquakes originate. A great deal of seismic crustal exploration has been completed in the U.S.S.R. and Western Europe using the so-called DSS (deep seismic soundings) technique or WAR (wide angle reflection). Lately, the small angle reflection (NVR-near to vertical) using the most sophisticated techniques suggested by the experience of oil prospecting was also applied, mainly in the U.S.A., to the exploration of deep, non-sedimentary formations of the upper and lower crust and, through the 'M' discontinuity, down to the top of the lithospheric 'lid'. The two methods have different pecularities, both being subjected to limitations and constraints, the output of each technique giving results of different significance and very often complementary. It would be interesting to make a short review of these points before outlining the main achievements of deep seismic exploration. Finally, an outline will be given of the results obtained so far of a region characterised by strong lateral variations of the crustal structure (the Alps and the Italian peninsula).