Abstract

A total surface area of approximately 17,000 sq km is involved in this study. Aerial photographs (scale 1:40,000) and indexes (scale 1:100,000) were used. The total number of the detected lineations is 16,240. A multi-stage procedure was adopted for their recognition.

The surface geology of the region is dominated by basement exposures flanked by younger sedimentary formations ranging from Mesozoic to Tertiary in age. Granites-granodiorites, metavolcanics, and metasediments represent the major rock types of the basement.

The regional airphoto lineation pattern is characterized by a strong degree of preferred orientation in the directions northeast and (or) northwest and less significantly in north northwest, east northeast, west northwest, north northeast, north, or east directions. In any one place, the pattern may be essentially unimodal, but more commonly it is bimodal or polymodal with three, four, or five of the above-mentioned trends present. Maximum concentration of lineations is reported in the basement rocks. The pattern resembles the “regmatic shear pattern” of Sonder. It is decidedly Precambrian in age although strongly modified by the Tertiary rift tectonics of the Red Sea.