Arid
DOI10.1007/s12517-008-0030-0
The role of the Najd Fault System in the tectonic evolution of the Hammamat molasse sediments, Eastern Desert, Egypt
Abd El-Wahed, Mohamed A.
通讯作者Abd El-Wahed, Mohamed A.
来源期刊ARABIAN JOURNAL OF GEOSCIENCES
ISSN1866-7511
EISSN1866-7538
出版年2010
卷号3期号:1页码:1-26
英文摘要

The Hammamat molasse sediments of the Eastern Desert of Egypt were deposited in isolated basins formed during an initial stage of orogen parallel N-S extension (650-580 Ma) in the Neoproterozoic time. Supply of sediments to the molasse basins began after the eruption of Dokhan volcanics (602-593 Ma), exhumation of core complexes (650-550 Ma), and intrusion of late tectonic granites (610-550 Ma). The late Neoproterozoic structures in the molasse sediments include: (1) NNW-directed thrusts due to NNW-SSE shortening (650-640 Ma), indicated by the presence of NE-, ENE-, and WSW-trending folds and NNW-directed thrusts. (2) SW- and NE-directed thrusts due to ENE-WSW constriction during oblique convergence and arc accretion at around 640-620 Ma. Many of the map-and mesoscopic-scale NW-trending folds in the core complexes, the molasse sediments, and the Neoproterozoic nappes in the Eastern Desert are related to this event. Sinistral shearing along the Najd Fault System (650-540 Ma) resulted in the development of subvertical foliation, subhorizontal stretching lineation, and NW-trending tight folds overprinting earlier folds. Stretched pebbles are oriented NW-SE and WNW-ESE in the molasse basins localized within the Najd Fault System, and NE-SW in the basins outside the influence zone of this NW-trending fault system. Strain estimated using pebbles from nine molasse basins indicate that the amount of strain differs from one basin to another and from one place to another within the same basin. Weak tectonic strain (Rs=2.16-2.24) is obtained from post-orogenic basins; moderate strains are reported from foreland basins (Rs=2.37-3.18), whereas moderate to high tectonic strains are recorded from the intermontane basins (Rs=2.40-4.36). The obtained tectonic strain and K values indicate that the flattening strain prevails in the post-orogenic and foreland basins, whereas as both constrictional and flattening strains are recorded in intermontane basins. Strain variation from one basin to another and within the individual basin is attributed to presence of thrust and sinistral shear zones. Away from the deformed zones, the pebbles show no significant stretching. Two phases of thrusting and an episode of transpressional sinistral shearing are the latest structure features of the East African orogeny in the Arabian-Nubian Shield.


英文关键词Tectonic evolution Molasse basins Strain analysis Constriction Najd Fault System Transpression Eastern Desert Egypt
类型Article
语种英语
国家Egypt
收录类别SCI-E
WOS记录号WOS:000276932800001
WOS关键词METAMORPHIC CORE COMPLEX ; OBLIQUE CONVERGENCE ; DOKHAN VOLCANICS ; CRUSTAL GROWTH ; MEATIQ DOME ; SHEAR ZONES ; GEOCHEMISTRY ; COLLISION ; ORIGIN ; GRANITOIDS
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/2XILL650/163258
作者单位(1)Tanta Univ, Fac Sci, Dept Geol, Tanta 31527, Egypt
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GB/T 7714
Abd El-Wahed, Mohamed A.. The role of the Najd Fault System in the tectonic evolution of the Hammamat molasse sediments, Eastern Desert, Egypt[J],2010,3(1):1-26.
APA Abd El-Wahed, Mohamed A..(2010).The role of the Najd Fault System in the tectonic evolution of the Hammamat molasse sediments, Eastern Desert, Egypt.ARABIAN JOURNAL OF GEOSCIENCES,3(1),1-26.
MLA Abd El-Wahed, Mohamed A.."The role of the Najd Fault System in the tectonic evolution of the Hammamat molasse sediments, Eastern Desert, Egypt".ARABIAN JOURNAL OF GEOSCIENCES 3.1(2010):1-26.
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