干旱区生态环境知识资源中心(Arid): Mineral and bulk-rock chemistry of Shadli bimodal metavolcanics from Eastern Desert of Egypt: Implication for tectonomagmatic setting and Neoproterozoic continental growth in the Arabian-Nubian Shield

Arid

DOI	10.1016/j.lithos.2019.04.026
	Mineral and bulk-rock chemistry of Shadli bimodal metavolcanics from Eastern Desert of Egypt: Implication for tectonomagmatic setting and Neoproterozoic continental growth in the Arabian-Nubian Shield
	Abdel-Karim, Abdel-Aal M.1; Ali, Shehata 2; El-Awady, Amr 1; Elwan, Waheed 1; Zaki, Mohamed Khedr 3; Akihiro, Tamura 4
通讯作者	Ali, Shehata
来源期刊	LITHOS
ISSN	0024-4937
EISSN	1872-6143
出版年	2019
卷号	338 页码:204-217
英文摘要	The Neoproterozoic Shadli metavolcanics in the Eastern Desert of Egypt have been conventionally categorized as a bimodal island-arc association. The present study deals with Shadli metavolcanics of three areas: Hamama in the central and Darhib and Atshan in the southern Eastern Desert of Egypt. They contain both mafic and felsic compositions and display a bimodal nature. Geochemical classification indicates that the mafic end-members are tholeiitic basalt and basaltic andesite whereas the felsic ones comprise calc-alkaline dacite and rhyolite. Mafic end-members show flat to slightly LREE-depleted patterns comparable to normal MORB produced from a depleted mantle source. Major element data indicates affinity to arc-related non-cumulative mafic rocks. The obvious negative Nb and positive Pb anomalies, the nearly flat REE patterns together with pyroxene chemistry are characteristic of island-arc tholeiitic suite. Accordingly, we suggest that their primary magma was derived from partial melting of a depleted mantle source metasomatized by subduction-related slab fluids/melts. Felsic end-members exhibit magnesian character consistent with a relatively hydrous, oxidizing magma and subduction-related source. Their weakly peraluminous character and calc-alkalic to calcic compositions are characteristics of arcrelated magmas. Moreover, the negative Nb and Ti anomalies suggest an influx of subduction-related slab fluids/melts. Their SiO2 contents are too high to represent magmas directly derived by partial melting of a mantle source. So, the high SiO2 and Al2O3 and the low MgO contents suggest melting crustal source. The high Y/Nb ratios (> 1.2) confirm that they were generated from crustal source. Actually, their Ce/Pb ratios (average of 2.66) are affiliated to those of continental crust and contrast typical mantle values. The weakly peraluminous and sodic nature is a typical feature of I-type magma. Therefore, their magmas were most likely derived by partial melting of thickened low-K mafic lower crust. Several lines of evidence let us speculate a genetic relationship between mafic and felsic end-members and that the felsic rocks were possibly evolved from the mafic melts that derived from metasomatized mantle. These comprise the close proximity and a coeval nature; the subalkaline character with approximately continuous trend; the similarity of trace element patterns; the arc-like signature, and the well fitness of major element data of the felsic rocks with melts derived from low-K mafic lower crust. The general tendency of silica increase with alkalis from mafic to felsic end-members may indicate that the felsic rocks were generated by fractional crystallization processes of the mafic magmas in the area. (C) 2019 Elsevier B.V. All rights reserved.
英文关键词	Neoproterozoic Bimodal Shadli metavolcanic Eastern Desert Egypt
类型	Article
语种	英语
国家	Egypt ; Japan
收录类别	SCI-E
WOS记录号	WOS:000471738200014
WOS关键词	CENTRAL INNER-MONGOLIA ; VOLCANIC-ROCKS ; GEOCHEMICAL CHARACTERISTICS ; CHEMICAL CLASSIFICATION ; COMPOSITIONAL GAPS ; CRUSTAL EVOLUTION ; THOLEIITIC BASALT ; WESTERN ANATOLIA ; GREENSTONE-BELT ; OKINAWA TROUGH
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/2XILL650/217512
作者单位	1.Zagazig Univ, Fac Sci, Geol Dept, Zagazig 44519, Egypt; 2.Menia Univ, Fac Sci, Geol Dept, El Minia 61519, Egypt; 3.Kafrelsheikh Univ, Dept Geol, Kafrelsheikh, Egypt; 4.Kanazawa Univ, Dept Earth Sci, Kanazawa, Ishikawa 9201192, Japan
推荐引用方式 GB/T 7714	Abdel-Karim, Abdel-Aal M.,Ali, Shehata,El-Awady, Amr,et al. Mineral and bulk-rock chemistry of Shadli bimodal metavolcanics from Eastern Desert of Egypt: Implication for tectonomagmatic setting and Neoproterozoic continental growth in the Arabian-Nubian Shield[J],2019,338:204-217.
APA	Abdel-Karim, Abdel-Aal M.,Ali, Shehata,El-Awady, Amr,Elwan, Waheed,Zaki, Mohamed Khedr,&Akihiro, Tamura.(2019).Mineral and bulk-rock chemistry of Shadli bimodal metavolcanics from Eastern Desert of Egypt: Implication for tectonomagmatic setting and Neoproterozoic continental growth in the Arabian-Nubian Shield.LITHOS,338,204-217.
MLA	Abdel-Karim, Abdel-Aal M.,et al."Mineral and bulk-rock chemistry of Shadli bimodal metavolcanics from Eastern Desert of Egypt: Implication for tectonomagmatic setting and Neoproterozoic continental growth in the Arabian-Nubian Shield".LITHOS 338(2019):204-217.