Arid
DOI10.1016/j.jafrearsci.2014.03.022
Magnetic fabrics and Pan-African structural evolution in the Najd Fault corridor in the Eastern Desert of Egypt
Abdeen, Mamdouh M.1; Greiling, Reinhard O.2; Sadek, Mohamed F.1; Hamad, Sayed S.
通讯作者Abdeen, Mamdouh M.
来源期刊JOURNAL OF AFRICAN EARTH SCIENCES
ISSN1464-343X
EISSN1879-1956
出版年2014
卷号99页码:93-108
英文摘要

In order to assess the Pan-African structural evolution from early orogenic fabrics through Najd wrenching to the latest orogenic collapse/extension, the authors used field work, aided by aerial photographs and satellite images. This work is complemented by the study of the anisotropy of the magnetic susceptibility (AMS, or magnetic fabric). The Pan-African rock associations of the Um Gheig-Kadabora area can be divided into a lower tier composed mainly of amphibolite-migmatite and granitoid gneisses, and an upper tier of ophiolitic rocks, metavolcanics and their related volcaniclastics, and molasse-type Hammamat sediments. Both these units are intruded by late orogenic granitoid plutons and dykes. The lower tier is exposed in a domal structure in the El Sibai area, the upper tier forms a series of weakly to highly deformed thrust units, called Pan-African Nappes here, which are dissected by high strain shear zones. According to their age, these rock units are divided here into early and late-orogenic. The early orogenic rock association is characterized by medium-high metamorphic grades. The late orogenic rock association is characterized by low metamorphic grade. The rocks in the upper tier form a series of low angle thrust sheets, which are bounded by NW-striking high angle shear zones related to the Najd Fault System. The early orogenic rocks show a polyphase structural evolution with early folds, thrusts, and strike-slip shear zones. The late orogenic rocks show a relatively weaker deformation. The latest intrusives studied here are the dykes dissecting the late orogenic Kadabora granite. In the present work magnetic fabric data document the deformational features in detail and assess the role of the Najd Fault System in the deformational evolution. A strong variation in volume susceptibility of various rocks, due to their variations in mineral composition, is observed. Lower values are in the range of 10(-6) SI units for late-orogenic alkaline granite and the dykes dissecting it, the highest susceptibilities exceed 7 x 10(-2) SI units in magnetite-bearing serpentinite. Early orogenic rocks are characterized by relatively high anisotropies (P’ up to 1.7) and are deformed in numerous shear zones. Most of these shear zones can be related to the Najd Fault System. In contrast, late orogenic sediments and intrusives show mostly low anisotropies. However, magnetic lineations are still distinctly oriented parallel with the Najd Fault trend. The very latest Pan-African intrusives, the broadly N-S trending dykes crosscutting the Kadabora pluton, imply c. E-W directed extension. Such an extension is consistent with the magnetic fabric in some of the dykes. Therefore, the Kadabora dykes mark the end of Najd wrenching and a late stage of extension in this part of the Eastern Desert of Egypt. The other dykes display mostly primary fabrics, related to magma flow during their intrusion and are thus post-deformational with regard to the Pan-African orogeny. (C) 2014 Elsevier Ltd. All rights reserved.


英文关键词Arabian-Nubian Shield Pan-African Anisotropy of magnetic susceptibility (AMS) Um Gheig-Kadabora Najd Fault System Late-tectonic extension
类型Article
语种英语
国家Egypt ; Germany
收录类别SCI-E
WOS记录号WOS:000345540900008
WOS关键词ARABIAN-NUBIAN SHIELD ; CORE COMPLEX ; OBLIQUE CONVERGENCE ; TECTONIC EVOLUTION ; SAUDI-ARABIA ; ANISOTROPY ; GEOCHEMISTRY ; SUSCEPTIBILITY ; NAPPES ; PETROGENESIS
WOS类目Geosciences, Multidisciplinary
WOS研究方向Geology
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/182881
作者单位1.Natl Author Remote Sensing & Space Sci, Cairo, Egypt;
2.Karlsruhe Inst Technol, Inst Angew Geowissensch Strukturgeol & Tektonophy, D-76187 Karlsruhe, Germany
推荐引用方式
GB/T 7714
Abdeen, Mamdouh M.,Greiling, Reinhard O.,Sadek, Mohamed F.,et al. Magnetic fabrics and Pan-African structural evolution in the Najd Fault corridor in the Eastern Desert of Egypt[J],2014,99:93-108.
APA Abdeen, Mamdouh M.,Greiling, Reinhard O.,Sadek, Mohamed F.,&Hamad, Sayed S..(2014).Magnetic fabrics and Pan-African structural evolution in the Najd Fault corridor in the Eastern Desert of Egypt.JOURNAL OF AFRICAN EARTH SCIENCES,99,93-108.
MLA Abdeen, Mamdouh M.,et al."Magnetic fabrics and Pan-African structural evolution in the Najd Fault corridor in the Eastern Desert of Egypt".JOURNAL OF AFRICAN EARTH SCIENCES 99(2014):93-108.
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