STRUCTURE, PHYSICAL-PROPERTIES AND LATERAL HETEROGENEITIES OF THE SUB-CRUSTAL LITHOSPHERE FROM LONG-RANGE DEEP SEISMIC SOUNDING OBSERVATIONS ON CONTINENTS

Long-range explosion seismic profiles on continents with penetration to a depth of about 100 km revealed both vertical and lateral variations of structure and physical properties in the subcrustal lithosphere. Findings from all available continental long-range profiles are compiled. The most important result is the discovery of unexpectedly high in-situ velocities of up to 8.7 km/s and larger, which is indirect evidence of the existence of anisotropic minerals with a preferred orientation in the subcrustal lithosphere. There is also direct evidence for the presence of anisotropy in the topmost mantle of some regions as large as observed in the oceans. The vertical gradient of velocity is larger than the gradient due to self-compression and is different in various parts of the continents. This is indicative of lateral variations in the continental subcrustal lithosphere. © 1979.