GRANITIC RING COMPLEXES AND POST PRECAMBRIAN HOT SPOT ACTIVITY IN THE SOUTHEASTERN DESERT, EGYPT | ||||
| Journal of Egyptian Geophysical Society | ||||
| Volume 10, Issue 1, 2012, Page 107-115 PDF (806.37 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jegs.2012.384985 | ||||
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| Author | ||||
| S.M.M. Hanafy | ||||
| Nuclear Materials Authority, P. O. Box 530 El Maadi- Cairo, Egypt | ||||
| Abstract | ||||
| The Post Precambrian ring complexes in Egypt represent an excellent example of the type of alkaline ring complexes associated with intraplate hot spot activity, ensialic melting, and incomplete rifting. The high resolution SRTM Digital Elevation Model with the recently published GRACE gravity has been optimally combined to improve the regional gravimetric geoidal model. This data integrates with the geochronology of the anorogenic alkalic rocks dates that suggest three phases of Post Precambrian igneous activities in Egypt. A striking correlation is shown between the patterns of geoid departure from reference ellipsoid in Egypt, attributed to inhomogeneities in the mantle, and the crustal framwork. The effect of these mantle plumes, over which Egypt has been drifting for the past 230 ± 20 m. y. of African plate movement, suggests that the hot spot activity was responsible for emplacement of alkalic rocks, for tectonic adjustments and for increased geothermal gradient that created favorable ore-concentrating environments in the basement rocks. Evidence supporting this idea is provided. The development of the ring complexes is interpreted in terms of a model consisting of four successive stages of structural, volcanic, and plutonic events: cauldron subsidence, ring dike intrusion, erosion of the volcanic highlands, and intrusion of central pluton with unroofing of the central pluton | ||||
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