| Popis: |
Approximately 100,000 air photo lineations in most of the Eastern Desert of Egypt were identified and mapped from aerial photographs of scale 1:40,000 and photo indices of scale 1:100,000. Their orientations were statistically analyzed at the 99% probability level using the Poisson distribution, and the analysis indicated that the N.W. and E.N.E. trends are statistically significant, equally predominant and regionally persistent over the entire area. In addition, the W.N.W. and North trends, although their areal persistence is limited, are also found to be statistically significant. Orientations of the identified significant peaks are believed to reflect the predominant structural grain of the area. The E.N.E. structural trend was found to be affiliated more to the basement complex than to the Cretaceous and Focene sedimentary cover where the dominant trend is N.W. Despite their variable affiliation to time–rock units, the orientations of the E.N.E. and N.W. structural grain bear no significant relationship to the time–rock units of the area. The E.N.E. and N.W. structural trends, among others, are a part of the structural grain of the African shield. Rift-related stresses led to the differential enhancement and probably slight modification of the pre-rift structural grain. The geometric relationships of the E.N.E. and N.W. trends to the Red Sea rifting trend (one normal and one parallel to the rift) resulted in their rejuvenation and vertical propagation. |
