Arid
DOI10.1016/j.lithos.2008.12.014
Geochemistry and tectonic evolution of the Neoproterozoic Wadi Ghadir ophiolite, Eastern Desert, Egypt
El-Rahman, Yasser Abd1,2; Polat, Ali1; Dilek, Yildirim3; Fryer, Brian1,4; El-Sharkawy, Mohamed2; Sakran, Shawki2
通讯作者El-Rahman, Yasser Abd
来源期刊LITHOS
ISSN0024-4937
EISSN1872-6143
出版年2009
卷号113期号:1-2页码:158-178
英文摘要

We report new geochemical data from the Neoproterozoic ophiolite in the Wadi Ghadir area, Eastern Desert, Egypt. The Wadi Ghadir ophiolite (WGO) is composed of layered and isotropic gabbros and amygdaloidal to porphyritic pillow lavas. Both the gabbroic rocks and the pillow lavas are intruded by dike swarms with different chemical affinities and spatial orientations. The WGO occurs in an ophiolitic melange (Wadi Ghadir melange, WGM), and both the WGO and WGM are intruded by granitic rocks to the west.


On the basis of Zr and Y variations, units of the WGO are classified as tholeiites (e.g., gabbros, amygdaloidal pillow lavas, D1, and D3 dikes).The late-stage D4 dikes show a calc-alkaline affinity, whereas porphyritic pillow lavas and D2 dikes have a transitional character. All ophiolitic units display subduction zone trace element signatures characterized by the enrichment of LILE over HFSE and negative Nb-Ta anomalies. Tholeiitic rocks are further divided into LREE-depleted (gabbros, D3 dikes) and LREE-enriched (amygdaloidal pillow lavas, D1 dikes) groups. Light REE-depleted tholeiitic rocks were derived from melting of a slightly depleted mantle source, whereas the LREE-enriched tholeiitic rocks were derived from a fertile N-MORB source. Calc-alkaline D4 dikes are characterized by steep REE patterns and have low Zr/Nb ratios (23-29), indicating melt contribution from an enriched mantle source, such as sub-continental lithospheric mantle and/or garnet peridotite. The transitional group has LREE-enriched patterns, but its degree of REE enrichment and Zr/Nb ratios are intermediate between the tholeiitic and calc-alkaline groups.


The WGO is interpreted to have formed in a back-arc setting behind the Nugrus volcanic arc developed above a NE-clipping subduction zone. The collision of this arc-back-arc system with the passive margin of the Nubian shield (Hafafit dome) resulted in the accretion of the Nugrus arc and the WGO onto the Nubian continental margin and in the initiation of a new subduction zone dipping SW beneath the newly accreted arc-back-arc crust and Hafafit dome. The establishment of this new Andean-type continental margin produced the calc-alkaline D4 dikes, leucogabbros and granitoid plutons intrude the Hafafit dome, the WGO, and the ophiolitic melange. (C) 2009 Elsevier B.V. All rights reserved.


英文关键词Ophiolites Ophiolitic melange Back-arc basin Active continental margin Arabian-Nubian Shield Egypt
类型Article
语种英语
国家Canada ; Egypt ; USA
收录类别SCI-E
WOS记录号WOS:000272370500009
WOS关键词BACK-ARC BASIN ; ISUA GREENSTONE-BELT ; NUBIAN SHIELD ; FRACTIONAL CRYSTALLIZATION ; PROTEROZOIC OPHIOLITES ; ELEMENT MOBILITY ; VOLCANIC-ROCKS ; LOW-TI ; ZONE ; PETROGENESIS
WOS类目Geochemistry & Geophysics ; Mineralogy
WOS研究方向Geochemistry & Geophysics ; Mineralogy
资源类型期刊论文
条目标识符http://119.78.100.177/qdio/handle/2XILL650/161895
作者单位1.Univ Windsor, Dept Earth & Environm Sci, Windsor, ON N9B 3P4, Canada;
2.Cairo Univ, Dept Geol, Giza 12613, Egypt;
3.Miami Univ, Dept Geol, Oxford, OH 45056 USA;
4.Univ Windsor, Great Lake Inst Environm Res, Windsor, ON N9B 3P4, Canada
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GB/T 7714
El-Rahman, Yasser Abd,Polat, Ali,Dilek, Yildirim,et al. Geochemistry and tectonic evolution of the Neoproterozoic Wadi Ghadir ophiolite, Eastern Desert, Egypt[J],2009,113(1-2):158-178.
APA El-Rahman, Yasser Abd,Polat, Ali,Dilek, Yildirim,Fryer, Brian,El-Sharkawy, Mohamed,&Sakran, Shawki.(2009).Geochemistry and tectonic evolution of the Neoproterozoic Wadi Ghadir ophiolite, Eastern Desert, Egypt.LITHOS,113(1-2),158-178.
MLA El-Rahman, Yasser Abd,et al."Geochemistry and tectonic evolution of the Neoproterozoic Wadi Ghadir ophiolite, Eastern Desert, Egypt".LITHOS 113.1-2(2009):158-178.
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